This news flash about a seemingly obscure topic is of immediate importance to all our architect Title 24 clients -and it’s good news for a change. The Quality of Insulation Installation credit is a HERS test that can help design projects to achieve Title 24 energy compliance, and we’ve had a couple of nasty surprises with it in the past.

Apparently, up until around yesterday, the California Energy Commission did not officially recognize the QII test as valid for open-cell spray foam. Our insulation expert James Morshead of SDI Insulation actually sent me an urgent email yesterday with the news, saying:

Today the California Energy Commission stepped out of the 1980′s and into the 1990′s! The 1/2 pound density spray foam QII check list has finally been approved after long delays.

There will be further revisions and refinements but our State has finally caught up in its own way. They have finally acknowledged what the rest of the country has known and what we have known in our area for years; spray foam works whether its closed cell 2 pound density or open cell 1/2 pound density.

Now on to fixing the U-Value tables!

Active lobbying at the CEC is necessary

As usual, James was an endless trove of insider information. Apart from the news itself, the way that this came about was very revealing of the CEC’s  inner working processes. Most of us don’t understand how or why regulations are the way they are, or how agencies like the CEC solicit input from the public. Apparently one must be prepared to show up in Sacramento at multiple hearings, cultivate deep relationships with CEC staff, sift through the raft of proposed changes for the few items that might be relevant to your industry or situation, and be prepared to pounce on proposed changes with a formally structured submittal process. In other words, hire a full-time lobbyist.

A QII teaching case with the New Solar Homes rebate

We’ve run into some issues on the QII test before, where we’d called it out for extra credit on a Title 24 report on a project that was going for the New Solar Homes rebate. The house had to beat Title 24 by 15% to qualify. James Morshead was actually the insulation installer on that job, and clearly remembered how the HERS rater – NOT one of our Green Compliance Plus Affiliates – flatly refused to accept the low-density spray foam. Closed-cell was fine, but open-cell? No way. This was maybe the first time we’d ever used the QII credit, and nobody, including our other HERS raters, could tell us much about this obscure little omission that suddenly threatened the validity of the project’s energy compliance documentation – and the NSHP rebate. There was much tearing of hair and gnashing of teeth all around.

This close-up shows examples of open cell and closed cell spray foam, also known as low-density and high-density foam. Each cell in the high-density foam is closed, making it a better air barrier - which increases its insulating value.

Whys’ this QII change so darned important?

What are the ramifications of this change and how did it come about? “The recognition of open-cell spray foam has been in process for six and a half years,” said James. “We at SDI didn’t know how the CEC process worked. We thought the CEC would be actively looking at the market to incorporate new developments in a proactive way. But they’re not set up to do that. They’re set up to be reactive, influenced by lobbying input from stakeholders in the marketplace.”

He mentioned a long-ago fight between manufacturers of cellulose and fiberglass insulation, each of whom pushed to have their own products recognized as higher efficiency (higher R value) than the other. “That’s normal business. The CEC is a government agency, and that means that they’re encumbered themselves by a lot of regulatory process. They’re restricted by the system themselves. They rely on input from competing parties, and they solicit information by saying, ‘We want your input.’ They rely on the stakeholders to approach them and provide the necessary technical information.”

But presenting this input to the CEC can be an uphill battle. James mentioned meetings that would be cancelled without notice, web site meeting schedules that were not updated to reflect changes or cancellations, and a very skeptical audience. “They’re coming from an analytical and academic standpoint, but they’re NOT in the field.” And that’s the main point of this discussion, is that until the CEC actually went out to see a low-density spray foam installation, they didn’t believe it worked AT ALL. “They were writing regulations without ever having seen it in action.”

James went on to emphasize that he didn’t fault anyone at the CEC, in fact he admired their work and didn’t envy their task. They’re overworked, underfunded, well-intended, and very committed to the overall goals of helping California to achieve greater energy efficiency. They are doing their absolute best within cumbersome bureaucratic processes that they can’t change, either. To get an an idea of how slow the cycles are for code revisions, consider that the current version of the California energy code, the 2008 code, actually didn’t go into effect until 2010. And, some of its provisions weren’t enforced across the board until October of 2011.

Meritage Homes – a study in foam

Then we got on the topic of Meritage Homes, a high-end home developer who was apparently instrumental in adopting and demonstrating the real value of spray foam. Meritage’s Green FAQ page actually talks about the building envelope as separate from the appliances. James told me that Meritage had decided to use 100% spray foam in all its new developments. Their homes weren’t selling, because of the economy of course – not because the homes were bad. Nobody was buying anything, no one could get financing.

“But then, someone convinced them to foam their homes. The first batch was in Houston, TX. And the spray foam was so effective as an insulator that it ended up causing them some problems early on. Suddenly, all the A/C units in the foam-insulated homes were grossly oversized! Short cycling and such. And they had mold problems as well. But they also realized: OMG! this foam works way beyond the calcs!”

Meritage Homes is a high-end home development company that has implemented energy efficient building envelopes as part of the core design.

And that’s where we get back to the CEC, and the California energy code, which has all sorts of tables and appendices with the allowable thermal values that you can use for various types of wall assemblies and insulations: wood frame, metal frame, etc. (They even have an appendix table for straw bales now.) So, even if your insulation is NASA-quality, the CEC’s Joint Appendices might disallow the use of its true performance capabilities when doing home energy calculations. Which isn’t really fair, considering how difficult it’s been to get even ordinary home designs to meet current California energy standards.

The deconstructed home as sales tool

Most of the time, developers will have a few finished-off model homes that prospective buyers can walk through to see what their home will eventually look like once it’s built. But Meritage did something different. They had a model home with cutout walls to show the interior building assemblies, including studs, wiring – and spray foam insulation. “I call it the deconstructed home,” said James.  “People now are smarter, more educated about building and energy efficiency. They want to see what’s inside. And sales took off! It was a totally new way to sell houses. Local building inspectors liked it, too.”

The homes weren’t selling for more money, but they were selling a lot faster – and, to investors, time is money. The quicker you can recover an investment, the less financing costs you have.

By showing a "deconstructed home" rather than the usual finished showcase model, Meritage Homes has educated homebuyers on construction techniques and efficient building envelopes. This image shows a deconstructed Meritage home from one of its San Antonio developments, as shown on housingzone.com.

CEC’s focus on new construction ignores issues for remodels

Then our conversation touched on another issue with the current California energy code, and that is its almost obsessive focus on NEW construction. One goal at the CEC is for all new homes built after 2030 should be Net Zero. But remodels to existing homes also impact the energy grid, and at least in California, remodels right now represent a significant portion of current construction activity. (This is according to James – I haven’t yet found any data specifically comparing either dollars spent or number of projects of each type, in CA).

Sometimes this results in a very artificial situation when we try to show compliance for a remodeling project. It becomes an exercise in hoping that the project qualifies for prescriptive and we don’t have to run an energy model. For example, if a remodel is not adding any square footage, but the total glazing area is over 20% of the floor area, there are situations where the project just doesn’t qualify for prescriptive compliance. And let’s say that this is a low-budget project; they’re changing out the heating system and enlarging a couple of windows and leaving the rest alone, maybe it’s mainly an interior remodel which doesn’t affect the building envelope.

Well, there are times we’ve had to run a whole-building model that included all portions of the existing home that aren’t being upgraded, but which aren’t built to current energy standards. It’s easy to go down a path of adding new energy measures that not only add to the cost of the project, but which can just get ridiculous. Open more existing walls to re-insulate? You could trigger a seismic upgrade. Replace all the windows? Well, maybe the old windows were still perfectly good, why throw them away? Is that “sustainable building”? I’ve spent hours reading the Residential Compliance Manual’s sections on alterations and remodels, and sometimes writing to the CEC, to find out what’s really allowable.

Trying to get a small remodel to pass California Title 24 compliance can be more agonizing than modeling new construction. This vintage contortionist image is from "The Circus, 1870-1950" published by TASCHEN.

QII checklists for each type of insulation didn’t include one for open-cell spray foam

James reminded me that the HERS rater has to follow different QII checklists based on which type of insulation is used in the project. So there’s one QII checklist for fiberglass batt insulation, and a different checklist to use for blown-in, etc. Here’s a nice checklist writeup from ConSol, an energy group based in Stockton.

This checklist does not affect allowable R-values used in the Title 24 performance calculations. All it does is say that insulation should be installed evenly with no air gaps, empty spots, or compression, and that wall cavities should be sealed to limit air flow through permeable insulation types. The extra credit is really a make-up because the assumption is that typical insulation installation procedures are so shoddy that substandard installations are the norm rather than the exception. So, what’s not to like about open-cell spray foam exactly? And yet, because the CEC had no official checklist that was specific to open-cell, and they didn’t want to lump open-cell and closed-cell together, the omission has led many HERS raters to conclude that low-density spray foam was simply not allowed for the QII credit. That may in fact have been the official CEC policy, too.

Some HERS raters have very extensive backgrounds in building efficiency, construction, and green building; others just don’t have the same depth of knowledge. That’s one reason we chose to list some HERS raters on Green Compliance Plus who we felt had a better grasp of the underlying principles behind Title 24 energy compliance. Our HERS rater affiliates are people with multiple credentials: some are HERS and GreenPoint Raters, some also have CEPE certification, and most have other creds ranging from Energy Star to BPI to LEED for Homes. They already have experience working with integrated project teams on custom home projects, and are more proactive about anticipating potential situations ahead of time or recommending solutions instead of just showing up for the inspection and saying, “Well, you fail, and there’s nothing I can do to help. You won’t get your rebate after all. ‘Bye, now.”

The CEC doesn’t always realize these ramifications until they’re pointed out

On the above mentioned NSHP case study, when James brought this up to the CEC staff and engineers, they were appalled. They had never dreamed that their policies would ever lead to a situation like this. The HERS rater had said, rather erroneously, “This product doesn’t work. Therefore, it’s not allowed.” What he really should have said was, “This product doesn’t have an authorized CEC checklist. And it’s still not allowed.”

Checks and balances to prevent cheating are well intentioned, but they can really gum up the works

“The CEC really wants to discourage cheating,” said James. There are certainly more steps to verification now than in the 2005 code. The whole CalCERTS registry process, with online filing of  the tandem forms for the Title 24 energy compliance report, the installation certificates, and then the HERS certificates, is a great idea but a royal pain in the bum. The online workflow is especially agonizing for custom remodel projects. The CalCERTS support folks are very nice and they also have to follow a ton of regulations that attempt to cover every possible home construction scenario; they’ve never had to consider a different workflow for custom homes where an architect is directly involved.

The code update process is complex and unforgiving, not unlike San Francisco’s planning and approvals process.

So – what if someone wants to advocate for, say, a better attention to remodels, or to custom architect-designed homes? You’d better have a full-time staff person on the job. “The process is so cumbersome, with hearings, submittals, and a lot of 45-day language,” said James. (Really it’s just like the SF planning process) “It’s really arcane – miss something and you’re dead.”

Other industries have their own issues to push for in the energy code. “HVAC, energy consultants, builders… there are a few people who practically sleep in their cars down at the SMUD building in Sacramento.”

It helps to establish a good rapport with the CEC staff, who got high marks from James for dedication and responsiveness. “If you know the system really well, you can know which events are important, but you can’t tell just by looking at the CEC site. It’s a labyrinth, and you need a guide. Try to have a relationship with the CEC staff. They can help you get your voice heard.”

Is the Net Zero goal realistic and achievable by 2030?

James thinks that the goal of having all new homes built in California after 2030 be Net Zero Energy is unrealistic, and not the best way to reduce overall building energy use statewide. “NZE should be affordable to more people than it is right now. We should be making it easier for people to comply even as we tighten the standards. It would be better to reduce energy consumption by 40-50% rather than try for some exotic concept like Net Zero. Go for more basic stuff – air sealing, HVAC sizing, more credit for unventilated roof assemblies.”

“Net Zero Energy is a great idea,” he continued. “But in the construction industry, there are so many different kinds of people involved. There are builders large and small, plan checkers, building inspectors, HERS raters, architects, energy consultants… no one knows how to do it right yet when it comes to energy compliance. Right now, this education is being force-fed into the system when people aren’t ready. NZE is such a complex concept, it requires a very integrated approach. If you push it on people too fast, it’ll be a disaster in the implementation.”

I can’t argue with him there.

Just last month, we interviewed the landscape architecture firm Arterra LLP on our sister blog, The Architect’s Take. Kate Stickley and Vera Gates were so much fun that I thought I’d ask them about Living Roofs – not exactly energy compliance, but a “green building” topic nonetheless. Turns out they’ve done several, and as landscape architects, they bring an artistry and a focus on creating a meaningful sense of place… it’s not just a functional piece of “turf” for a corporate building, where no one ever actually goes up there to enjoy it.

What’s the definition of a “living roof” exactly?

A living roof consists of a thin strata of vegetation and soil, contained within the structure of a building roof and integral to it. Similar to a natural ledge, a select variety of plant types can be grown in the strata, creating additional garden space for use or viewing. Industry definitions characterize different types of Living Roofs according to the depth of the soil strata:

Intensive: This is what we think of as roof gardens, where we have access and usable space. Soil is at least 6” deep. These gardens are intended to be viewed and used as gathering spaces and may include hardscape. They are like gardens planted at the ground level. When we do living roofs, this is more our focus than the thin-strata type as mentioned below.

Extensive: Where there is no use or access and the stratum is very thin. Soil is 1”-6” in depth, planting is treated in mass (as in sheets of succulents or grasses). These are not intended for human use. We don’t have much experience with the latter. For now, just note that the reasons for putting a living roof on a private residence might be different, more personal, than the rationale for installing one on a large corporate or public building.

There is a very good book available on living roofs called “Planting Green Roofs and Living Walls“, by Nigel Dunnett and Noel Kingsbury. Hydrotech is the living roof system we typically use, and they used to have a pretty good web site.

This image shows shallow and deep assemblies for living roofs from a single manufacturer (Carlisle).

What are some good residential examples – your favorites?

One project we did, we’ll call it the “Sky Garden” for the sake of our client’s privacy, involved very extensive roof gardens and some vertical living walls as well. Unfortunately we don’t have photos available at this time, but we can describe it a bit. The house is on a steep hillside, leaving very little usable outdoor space. There are several roof areas, all fully usable, including a fire pit, a patio, and a vegetable garden. Part of the roof is heavily shaded, and the other part gets a lot of sun; there are different plantings in each portion to take best advantage of the sun conditions.

Under the planted area, the roof itself has several drainage areas similar to what you might have in an indoor shower. A layer of foam in each drain area acts as a leveler to maintain an even 6″ soil layer throughout. Rainwater runs underneath the foam to the drainage openings. Roof vents and other mechanical features are concealed inside decorative shrouds that relate to the building materials and guardrail.

[See drawing details further down in this article.]

The most interesting part in a way is the water management, something we mentioned in our last discussion with you as well. Our “Sky Garden” project actually uses four sources of water, in a hierarchy that prioritizes water sources: first, grey water. Next, rainwater. Third, well water. Finally, if and only if all other water sources are dry, say during a drought, the roof garden can be irrigated using city water.

Here’s another recent project, a GreenPoint Rated house in Palo Alto, done in collaboration with architect Cathy Schwabe.

This roof garden designed by Cathy Schwabe and Arterra LLP is a good example of what can be done even with a very small space. The GreenPoint Rated home was designed by architect Cathy Schwabe, who notes that she and Arterra worked collaboratively on the design and detailing, with each firm taking the lead in specific areas.

Although we tend to work on projects where the roof garden is fully usable, it’s also possible to create small rooftop gardens just to add visual interest in an urban setting, especially if the view out the window would otherwise be unappealing – bare rooftops or concrete walls, for example.

What are the benefits of having a living roof? Why would you want one?

The greatest benefit of having a living roof is expanded livable and/or visual garden space. For residential design, this is typically why you would want one. There are many additional benefits that may or may not be a factor, depending on the project, program and climate.

Additional benefits can include:

• Great insulation quality for the building. Living roofs help cool the building in summer and retain warmth in winter.
• Increases longevity of the roof system, by protecting the membrane from ultra-violet light and extremes of temperature.
• Decreases heat sink effect on hot sites-most apparent on a neighborhood level, when many roofs are planted.
• Retains and slows water runoff during and after rain storms, releasing it slowly, over a prolonged period of time. This reduces risk of flash flooding in urban areas during heavy rains.
• Increases opportunity for plant life, habitat & wildlife.

Another green roof from Arterra LLP. A well-designed intensive living roof looks almost the same as ground-level landscaping.

Is there any hard data on these claims for energy savings, heat sink reductions, or comfort improvements?

Yes, but I don’t know that off the top of my head. A lot of research in Europe and Canada has been done. [In densely built-up urban settings, a certain percentage of the rooftops might need to be planted in order to achieve a noticeable change in the overall "urban heat island" effect. Even simply making more roofs light-colored instead of black tar can help.]

Can you have a living wall, too? (e.g. plain old invasive-species ivy)

Yes, there are several, naturally clinging vines. There are also structural green wall systems you can attach to a wall, which provide an armature of support for any vines to grow through. They are separate systems and structures that have different plant types, irrigation and details. There are a number of pre-made systems out there: Fyto Wall and  Tournesol VGM Modular Living Wall to name a few, plus the custom hydroponic system pioneered by Patrick Blanc. We have used both Fyto Wall and the Tournesol systems.

Living walls don't have to accommodate human foot traffic, and they can be quite elaborate. I wonder how much work it takes to keep them so neat-looking, though, and whether these walls have built-in access points on the back side, or whether the maintenance is all done via scaffolding. Left to right: Enrique Browne building in Santiago, Chile; Patrick Blanc living wall design; and a living wall design from Mingo Design.

One thing to point out is that living walls are in many ways a completely different animal from a living roof. We could probably write an entire article just about living walls. Different structures are used to hold the plants in place for a living wall than for a roof. The physics of verticality vs. horizontality affects how weight is supported, how water flows down and out, and of course plants grow upwards so they’ll look different growing on a wall than on a flat surface.

Being vertical, living walls can’t capture as much rainfall, and thus require more irrigation. Sometimes, a lot more. You wouldn’t create a living wall to save water! And they don’t help much with slowing down rain runoff, either. However, they can be a great asset in urban areas as a break from all the concrete, where space is at a premium, and you can’t expand horizontally.

Sounds like a living wall would be impossible in a desert, if they need that much watering.

It’s possible to do a living roof with succulents, but yes – a living wall, even an all-succulent one, would need too much water to be a good choice for a desert area.

When are living roofs NOT a good idea?

• On remodels where the existing structural system and waterproofing wasn’t originally designed to support the added weight of a living roof, where the structure has not been designed to take that load, and there is no budget or scope for reinforcing it. You also need a higher level of waterproofing because living roofs have a rim and might need to tolerate standing water if the drains get clogged up.

• If the roof is sloped more than 2:12 pitch. Sloping roofs are more complicated but they can be done, up to that 2:12 pitch.

• If the living roof area is only a small portion of the entire roofing area. Even for new construction, there is an economy of scale. The smaller the living roof, the less cost benefit it provides.

Drainage and overflow detail from one of Arterra LLP's living roof projects. Image courtesy of Design Ecology.

How much does it cost, as compared to a regular roof?

The range is broad. Simple seeded systems might drop down as low as $15 per SF. However something like our Marin project would be closer to $40 per SF. That includes everything except the roof membrane, which is an additional $8-$12 per SF. It can be hard to come up with a hard number for a project, because if the scope of work included extensive groundscaping and the roof garden is only one portion of that, there are economies of scale that can make it difficult to price that same roof garden as a separate entity.

What are the top things an architect should consider when adding a living roof for a home project?

• The living roof should be well integrated, correctly sized, and serve multiple purposes.
• Waterproofing is key and cannot be fudged.
• The living roof should be an element incorporated early in conceptual design. Curb and parapet detailing, structural engineering, and waterproofing are all integral to the design and the look of the overall building.

What might an architect have to do differently on a project with a living roof?

Decide sooner, rather than later. Adding a living roof later in the design process incurs a great additional cost. However, if a living roof is a possibility, it opens up so much opportunity to expand living space out and into the garden, on multiple levels throughout the home. It also provides an opportunity for an interesting visual feature, as seen from key living areas of the home that might otherwise not have an interesting view.

Parapet waterproofing detail from Arterra LLP, from one of their living roof projects. Image courtesy Design Ecology.

What sort of special consultants would you need to create a roof garden, aside from a landscape designer? What about installers?

There are manufactured systems readily available on the market today that provide all the information an installer would need. Typically a waterproofing specialist is involved, as with most roof installations today.

A landscape contractor typically installs the living roof system. They need to coordinate closely with the general contractor, the roofing subcontractor, and the waterproofing consultant, as the waterproof membrane must be covered as soon as possible after it is tested.

The division between the general contractor and landscape contractors’s scopes of work needs to be definite and clean. It’s best if the general contractor is responsible for the structural construction of the roof and the waterproofing. Then a water test can be done. When the membrane is deemed waterproof, the landscape contractor can begin installation of the layers of material, soil and plants.

This living roof example, courtesy of waterproofing experts Neumann Sloat Blanco Architects LLP, is in Marin, CA. NSB designed the waterproofing, drainage, and soil retention system.

The Neumann Sloat project is a good example of a “non-use” application, where you’re not using it as a patio, but you’re making a visual feature out of something that would otherwise just be an ordinary-looking garage roof.

How are living roofs put together? What are the major materials, components and systems?

They are basically a big bathtub, integrally built into the roof and parapet. First, the roof structure is monolithically waterproofed and heavily tested to ensure the waterproof membrane is intact. Then the pre-manufactured living roof soil system is installed. These vary slightly but they basically consist of a root barrier to keep plant roots from penetrating the roof membrane, a soft insulation layer (which protects the membrane), a drainage layer (like an egg crate), and a layer of filter fabric.

Layering of components from bottom to top are as follows:

• Roof deck (wood frame or concrete)
• Waterproofing
• Protection Board
• Drain Mat
• Geotextile/filter fabric
• Irrigation piping
• Soil
• Plants
• Mulch

Closeup of the Neumann Sloat Blanco living roof shown previously. Plantings here don't need mowing, and have mulch in between.

Along the perimeter of the building at the curb or parapet you will need:

• A curb, which must be at designed to be above the top of the soil
• Minimum 6” width of light-weight gravel between curb and soil area, separated by stainless steel edge restraint (Green Roof Solutions is one supplier)

For drainage:

• The roof deck must be sloped to drain underneath the soil layer. The roof design should include at least 2 drains that are waterproofed and hard piped out to the stormwater or rainwater catchment systems.
• The sloping of roof deck affects thickness of the soil profile above, and must be cross-checked with the project’s structural engineer.
• Lightweight foam board can make up depth difference if needed, to control weight.
• Inspection Chambers  (SS, Green Roof Solutions) will be needed at drains and irrigation valves.

Beneath a living roof is a waterproofed roof, with a rim, and adequate drainage. These stainless steel eyebolts will support a soil retention system. Image courtesy Neumann Sloat Blanco.

A specially formulated soil mixture is then brought in, the thickness of which varies. We prefer to work with a minimum of 9″ of soil, going as deep as 18″ in some situations. The medium tends to be very low in organic matter and have crushed lava or small gravel, which gives it enough heft that it won’t blow away.

Plants go in as they would in any garden although they are usually fairly small container stock. The whole thing is then mulched to secure the soil and insulate the plant roots. If hardscape elements, such as paving or decks, are required to be built over the green roof, that can be done in ways similar to how they would be installed onsite for ground-level landscaping. Hardscape features may be specially designed to minimize weight.

Hydrotech supplies most of these layers. You will pay a premium, because the pre-manufactured costs are usually higher than purchasing the same materials elsewhere. For instance, root barriers are used in ground-level landscaping and are a readily available material. However, Hydrotech requires you use all of their component layers in order to warranty their system. Some clients are willing to pay for this just for the peace of mind. However, a sound green roof system is entirely possible to achieve with products other than theirs.

A soil retention system such as this one is essential for living roofs that are on a slope. Image courtesy Neumann Sloat Blanco.

How do you decide what to plant on a living roof?

The living roof is really like a ledge planting. It’s more exposed. You have only a thin stratum of soil, with higher winds and fuller sun exposure than you might find on the ground level. Plants native to ledges and shallow soils often work well. Most grasses work very well. We design each project uniquely, according to site conditions, depth of planting soil, exposure, etc. There are a lot of resources available now to help in identifying plants that have done well on living roofs.

Another shot showing the soil retention system installed on the living roof for Neumann Sloat Blanco's Marin project. A copper parapet cap provides UV and physical protection for the single-ply membrane underneath. It is also more attractive than leaving the membrane exposed. Image courtesy Neumann Sloat Blanco.

Are living roofs heavy? Do you need structural reinforcement?

Yes, absolutely – especially if you’re going to be walking and sitting out there. They are engineered to assume that the drainage may fail and the whole “bath tub” could then fill up with water. The engineering design must be integrated into the overall design for the structure to take this potential condition into account.

What about retrofits or remodels?

It’s possible, depending on engineering. If the retrofit/remodel is being re-engineered anyway, it is a good possibility.

Do living roof projects ever run up against permitting issues or local building codes? There’s no special credit for them in the California energy-efficiency code, I know that, although green building codes such as CALGreen and BuildItGreen’s GreenPoint Rated system do recognize green roofs to some extent.

Building codes always apply, but we have not run up against anything unusual. If the living roof is accessible, it will need to meet codes for guardrails, etc. There are some LEED and BuildItGreen credits for living roofs, depending on multiple factors.

There are some fire departments that have a say on the plant materials used on living roofs. They review the planting as they would a ground-level landscape. Certain fire-prone plants are prohibited. If local fire codes specify highly fire-resistant roofing materials, they will probably be concerned that plant material should be fireproof as well. On one of our projects, the fire department also required that there be a walkable perimeter around the roof in case firefighters needed roof access during an actual emergency.

Here's another living roof in progress series, this one from Arterra LLP. First comes the framing of the roof and parapet.

What about waterproofing?

The waterproofing makes or breaks these systems, and there is simply no cheating this one. The waterproofing must be a monolithic membrane or there will be problems. That said, the technologies available now for waterproof systems are incredible. Hydrotech seems to be an industry leader. They provide several types of membranes as well and the component layers (including soil). Again, you have to use all of their components in order to get their warranty.

Arterra LLP living roof construction series, part 2: waterproofing layer. The waterproofing is the single most important thing to get right on a living roof. No cheating, no fudging, no shortcuts.

What about maintenance? Do owners need to hire a special service?

The garden needs to be irrigated, fertilized and maintained, as with any garden. Drains need to be serviced as with any roof drain. It is a man-made environment, just like any other landscape. But, roof gardens are more sensitive than gardens created on the ground in full-depth soil. While they may not take more man-hours to maintain than ground-level plantings, living roofs do require more frequent monitoring. Getting the irrigation dialed in correctly takes a bit of attention while the plants are growing in. Over time, they will require less time and be on a par with maintenance for ground-based plantings.

Arterra LLP living roof construction series, part 3: plant layout.

How do you keep a living roof healthy?

If you have planted the right plants and set the right irrigation, they will only need periodic fertilization and regular garden maintenance to stay healthy.

What about weather damage?

This can be a factor, of course. All conditions are more severe on a roof, and damage can occur. Wind is probably the greatest concern and affects the plant choices made.

How easy is it to add greywater irrigation?

Technically, it is easy. Building code sees it differently, though, and at this point I doubt you could get this approved in California. If you did, there would be some concern with a buildup of salts in the soil, so at best it would have to be a dual system, to ensure that you could periodically flush out the salts.

This New York City rooftop garden has quite a mix of plantings, including a small patio, flowers, what might be an herb garden, and even some sizable trees.

Are grey water and rainwater systems the same thing?

No! Grey water and rainwater catchment are two completely different things. Grey water is from household use: laundry, showers, and bathroom sinks. You can’t really store it long-term in a big cistern because it’s not as clean as, say, well water. Too many organisms can “bloom” in grey water. The way to think about grey water is that it’s continually replenished. You can use it right away, or same day, for landscape irrigation. If you have a household with a lot of kids, and a lot of laundry, you might generate a significant amount of grey water to make this worthwhile.

Rainwater catchment systems are an attractive idea but they can be expensive. You need a lot of storage tanks. Rainwater storage might cost around $1.50-$2.00 per gallon. Depending on your garden’s water needs, you could be spending tens of thousands of dollars just for the storage tanks.

Tell me more about water budgets. I assume you’d start by factoring in the average annual rainfall.

Yes, that is where you start, but then you have to identify supplemental water sources in case of a shortfall. It’s also dependent on the plantings, the area, and how shaded the roof area is. We do detailed water budgets as part of all our design projects.

Is a living roof just like having another lawn?

It can be, if you plant grass and mow it. All the accompanying maintenance of having a lawn would apply: heavy irrigation, weekly mowing, heavy fertilization and weeding. We don’t recommend it. Most of our plantings are not lawns. If we do incorporate grasses, they are no-mow natives or ornamental grasses.

Japanese architect Terunobu Fujimori has done some intriguing-looking designs that integrate living plants with slate finished walls. I don't know how water-intensive or maintainable they are, but Fujimori is using vegetation as an artistic medium in a way that preserves some of the cleaner lines in the design.

Can you put a living roof in any climate? What would you do different in Tahoe than in Livermore?

Yes, you can have one in any climate. Living roofs have been used extensively and for many years throughout Europe and Canada, so winter climates are fine. We don’t have much experience designing systems for northern climates, so we don’t know how they handle the snow load. We’d guess that it is mainly an engineering question. The main difference would be the plant choices, as those climates are so different.

Are there other design features that could interfere with a living roof? Certain types of roofing assemblies, tilted roofs, skylights, solar panels, vents, mechanical on the roof, etc.

Yes – all of these can interfere with or modify the design of a living roof. All of these factors should be considered as a whole in the early phases of design. Roof vents can be concealed, of course – solar panels would have to fight for space. And, local fire departments may require a walkable perimeter on a roof, which would also take away space from either gardens or solar arrays.

Some of the DIY living roofs look very untidy. I can’t imagine putting them on a Modern house.

Yes, they can be. That’s the old “hippie” look. We can design water-wise gardens that have a very sophisticated look, but don’t require a lot of water. Each living roof is designed to be in character with the rest of the project.

This images is from a web site promoting "Earth Houses" and it's got a sort of untidy, disheveled charm about it. It's probably not the look you'd want for a very minimal, Modern home design. However, it'll help more with slowing rainwater runoff than a very thin, close-mown piece of turf.

How do surrounding shade trees affect living roof design?

If you are fortunate enough to have mature trees high enough to shade the roof, it is a blessing. Shade is great. Typically, there is more of an effect from surrounding buildings casting shade or creating erratic wind patterns. Our “Sky Garden” project had shade from redwoods on once side and bright sun on the rest. It was designed like any other landscape: shade-tolerant plants on the side shaded by the trees, and drought-tolerant sun plants in the open areas.

Are there any cautionary tales worth mentioning?

Our experiences have been very positive. This is a wonderful way to expand livable and visually attractive space in tight urban settings and on properties with limited buildable space on the ground plane. Steep hillside sites are always looking for more area to create flat outdoor spaces, regardless of of the size of the lot.

The 5,000 year old monument of Newgrange in Ireland is a very early example of a "sod roof" with a multi-layered stone construction beneath.

Every so often at the AIA-San Francisco Small Firms group, we debate amongst ourselves whether getting our residential projects LEED certified is worth the effort. For most of us, with one-off custom residential new homes or remodels, the answer is no – too cumbersome and expensive. If someone is just looking for “green certification” for a California home project, the GreenPoint Rated system from BuildItGreen is a lot more flexible and user-friendly. However, there are a few architects who’ve really made a big push towards LEED certification on some of their homes. So, what are they getting out of it? How do you decide whether to go for GreenPoints or LEED, and what needs to happen with LEED for the process to go smoothly?

(Home shown above is designed by Sparano + Moody Architecture, and has earned LEED Silver certification. But LEED homes don’t all have to be in the wilderness, either.)

The Questionnaire

I took a straw poll amongst our design colleagues, one of our GreenPoint Rater affiliates, and also reached out to a few people that we don’t know – architects, builders, and developers – who’ve completed LEED-certified private homes in California. The questions were, more or less:

• Was it worth the effort?
• What did YOU get out of it?
• Did it add value to the property?
• How much did the rating process itself cost?
• What other additional costs were incurred?
• What can architects, builders, and homeowners do to make the LEED process go more smoothly?

We also discussed the relative merits of LEED vs GreenPoint Rated for private homes in California, including when to go for one vs. the other.

The Respondents

Numerous people took the time to share their opinions freely. In no particular order:

• Rob Lehman of Green Score Solutions. Rob has multiple credentials as a GreenPoint Rater, a HERS rater, and LEED AP, and he’s listed on our Green Compliance Plus affiliates page.

• Rich Williams of ArtHaus, LLC, a residential development company near San Diego. ArtHaus specializes in building sustainable high-end modern homes, and their goal is for all their projects to obtain LEED certification.

• Jonathan Feldman of Feldman Architecture. We’ve known Jonathan for years through the Small Firms Committee – he’s completed or is working on six LEED Platinum and two LEED Gold custom residences. He is a strong proponent of the LEED system.

• Dan Johnson of Arkin Tilt, a well-down Berkeley firm that is in the vanguard of sustainable residential design.

• Eco-Struction, a green builder in Ben Lomond, CA near Santa Cruz.

• Ann V. Edminster, home energy/green building consultant and author of the book “Energy Free” which we reviewed a few months back. She didn’t actually comment for this article, but she’s consulted extensively on LEED projects large and small, including helping design teams set priorities, analyze financial impacts, conduct contractor briefings, and prepare LEED compliance documentation. If you’re looking for a feasibility analysis to help decide whether or not to go for LEED, she might be a good place to start.

LEED and the Building Industry

It’s not just architects who care about it. Builders, developers, homeowners, and home energy consultants all have their own perspectives. Half of the private residences listed as LEED Platinum in California seemed to be credited to developers, builders, or design/build firms rather than architects. However, the majority of the LEED Platinum certified projects were large-scale enterprises like the California Academy of Sciences, multifamily housing, or public buildings – not private residences.

Developers Can Have Ideals, Too

Developers and production builders in general have a public image that seems to view them all as solely focused on making a quick buck. If there weren’t mandatory inspections and statewide energy codes like Title 24, the argument goes, they’d cut every corner, slap the homes together as fast as they can, and get the heck out before the homes started falling over. And if there weren’t environmental protections in place, these same profits-before-people villains would pave over every national park and fill them up with cheap condominiums.

Well, it seems that there’s more variety among people calling themselves “developers” than the stereotypes would suggest. I was surprised to see that around half of the LEED Platinum Homes in California were credited to either developers or design/build firms (developers who turn out a few homes at a time). And not all developers focus on tract homes, either.

One of our own projects from Mark English Architects, the Pepper Drive residence, is a GreenPoint Rated spec home built by a developer that earned a score of 113. Photo: Norma Lopez Molina

Project Scale is a Determinant

“LEED was developed more for production builders than for one-off projects. For one-off projects, GreenPoint Rating is more user-friendly and adaptable,” says Rich Williams of ArtHaus. “However, LEED certification confers a certain amount of prestige, and it’s got more brand awareness than, say GreenPoint Rating. A LEED Platinum certification means it’s the best you can get,” he continued. “A GreenPoint score of 220 is a great score, but people don’t really know what that means yet.”

This new home from residential developer ArtHaus is LEED Platinum certified. Their goal is to have every home they do be LEED certified. Photo: Ramona d'Viola - Ilumus Photography

It’s not just scale, but scope that’s important. LEED for Homes has some prerequisites that may involve a total gut rehab – opening and inspecting every wall and ceiling cavity. So you’d better already have planned on doing a thorough job on any remodel – including a thorough review of any existing HVAC and water heating systems. At least with a home that’s new from the ground up, there are no legacy components to worry about.

Sufficient scope also implies that there is sufficient budget: not only for the measures, but for the certification fees and the extra paperwork. I wasn’t able to get anyone to commit to a dollar amount for the owner’s construction budget as some sort of threshold to determine if LEED would be worthwhile on a particular project. But, the owner and architect should be prepared for upgrades to products, materials, components, systems, and installation procedures where needed to meet requirements – including baselines for energy efficiency. It’s not always something you can tack on later, either – you can insulate now, but even if the insulation is inspected during construction while the walls are open, if it’s not inspected by a LEED certified “Green Rater” – then you may not be able to claim the credit.

Why Did You Choose LEED?

Jonathan Feldman is one residential architect who’s worked on several LEED certified homes, including the award-winning Caterpillar House, a Carmel residence. Based on my conversation with him, the benefits he sees in LEED are:

• A structured and rigorous process
• Verified materials and products
• Tested and calibrated performance
• Process that is raising public awareness

“On our first LEED project, the client came to us very committed to sustainability. She felt that it was reckless the way the building industry largely ignores the devastating impact that it has on our environment,” said Jonathan Feldman of Feldman Architecture. “We were forced to take a wider and more thorough look at different areas of sustainable design, and LEED forced us to follow through with our early project commitments, and also to keep our clients, vendors, and builders committed. We received considerable goodwill from building departments, homeowners associations, and from the press because our project was the first LEED Platinum project in the area. The owners got a house where all the materials, products, and environmental strategies were more carefully considered, specified, installed, calibrated, and tested.”

The Caterpillar House by Feldman Architecture is LEED Platinum certified. Photo: Joe Fletcher

Quality control is an emphasis shared by both GreenPoints and LEED – in fact, any green building standard has to consider both construction quality and overall durability. What’s the point in building something that’s going to be torn down in a few years? Better to build it right the first time, and make it something worth keeping around.

Feldman warned that there was a steep learning curve on his first LEED project, but feels that it’s worth it – if it leads to a much-needed sea change in the building industry. “The more architects and builders go through the process, the easier it becomes. I also think that the more architects and builders share what they learn with each other, the easier it will be for all of us. There are those who don’t want to share what they’ve learned with those whom they view as their competition. I find this amazing. If we are truly concerned with making a dent in curbing the devastating effects of the building industry, then we really should be doing everything we can to help every building project move towards greater sustainability.”

Rich Williams from ArtHaus does it out of personal conviction. “LEED for Homes is a goal that I set for myself. I build stuff that I would want to live in. And with a spec home, LEED certification is a recognition of a benchmark. The biggest take-away from my experience building LEED and GreenPoint Rated homes is that we aren’t really ‘building green’, we are really building to a much higher standard of quality. Consumers will know, because of third-party verification, that the home that they will be living in should be more durable, should require less maintenance, should cost them a lot less to operate, should be more comfortable for them to live in, and (the most important one) should be WAY healthier to live in than other homes that are not being built to these standards. As the Mastercard commercials say, that last one is ‘priceless’. You folks understand how to build a better home, but a lot of folks out there don’t, so having these rating systems in place to provide guidance for doing so is extremely valuable, in my estimation.”

The value of having a structured process with some rigor to it was emphasized by several respondents, as a benefit to both GreenPoints and LEED. LEED might be considered as the stricter of the two, because unlike GPR, the bar to initial certification is a lot higher. Even an “average” home can get a GreenPoint score of 75 without too much effort, but to be LEED certified the home must meet a much larger list of mandatory measures.

Incentives

Rob Lehman reminded me that GreenPoint Rated homes are eligible for additional incentives under California rebate programs such as the New Solar Homes Partnership and California Advanced Homes. If the home is a total gut rehab with all new systems, it may qualify for these programs as “new construction”. So if the client is already thinking about going solar, the rebates can be substantial – and they’re bigger if the home is GreenPoint Rated.

So does that mean that NSHP and CAH ignore LEED certified homes? Not at all. California Advanced Homes rewards it, at least.

• In CAH, there’s a 10% bonus for “Green Home Certification” by a “recognized green building program” and there’s a 15% bonus if the home is 10% smaller than the LEED for Homes size threshold. Yep, LEED has something called Home Size Adjuster which penalizes larger homes.

• NSHP doesn’t appear to reference any green building certifications, although it does mandate energy efficiency. Why? My guess: NSHP is solely about solar power, and reducing home energy use has a direct impact on the PV system size, whereas using low-VOC materials has no impact on the solar array. Both programs use Title 24 as a yardstick – you have to beat Title 24 by 15% or more.

How Much Does LEED for Homes Cost to Do?

How much does it cost? GreenPoint Rating fees seem to be lower than those LEED certification, although I don’t have hard data to do a good fee comparison. Here are a few price points:

• Word of mouth on the street is that it costs $15,000 to get a private residential project LEED certified.

• Rich Williams quoted a fee of $5,000 for getting a 3,000 SF home LEED certified – that’s what it’s costing him – he didn’t include construction costs, though.

• Jonathan Feldman was a bit more specific: estimated rating cost of $5,000 – $10,000 in fees, required advisors, and testers, and another $8,000 – $12,000 for construction practices, materials, research, and design time. “Less in the cases where the clients manage the process themselves,” he added.

Cost analysis can be tricky, because some of it might be things you were planning to do anyway. And with something like LEED, which references other building standards such as Energy Star and (in California) Title 24 energy compliance, assigning weighted costs to requirements can be difficult. Some costs could be incurred during the energy analysis, which is required by both GreenPoints and LEED. In California, projects must exceed Title 24 energy efficiency standards by 15% or more. And, sometimes to get this, a particular project might need upgraded windows, more insulation, higher efficiency systems, or other measures. If you weren’t planning to do these things before, then yes – they’re additional. If you’re just going for the label, that might not be a good reason by itself to go for LEED – or any green certification beyond what local building authorities may require.

“Don’t do it just for the label,” warns Jonathan Feldman. “It’s asinine to jump through that many hoops just for a label. Do the measures because you were going to do them anyway.”

Commercial projects can cost a lot more. Rob Lehman mentioned a LEED certified multifamily project in San Jose with 90 units that cost $90,000 for the LEED certification! “There aren’t that many LEED Green Raters available and they’re expensive,” he noted. I don’t know how this broke out – I’m guessing it likely included the rating, the documentation, and the additional construction costs all rolled into one. And, for a large project like that, having the entire building LEED certified could boost sales and/or rental rates, “especially in certain areas,” he noted.

Does It Add Value to the Property?

Does LEED certification add value to the home? Depending on how you define “value”, here are a few possible definitions:

• A premium that homebuyers are willing to pay, as demonstrated by home sale data
• What realtors and listing services believe are the features that people care about
• What lenders are willing to finance when doing their value assessments of a sale property
• Something that brings the homeowner long-lasting satisfaction, comfort, and enjoyment

The problem is, we don’t really know how much value green building adds to single-family residences, because home listings don’t track green certifications of any kind. So, if a home sells for more, or sells faster, how do we even know whether “green” had anything to do with it? And how can we compare the value of a GreenPoint Rated home vs. a LEED certified one vs. an unrated home that nonetheless has the same green features as a rated one? Thus, data is anecdotal at best.

It seems that the general public is a lot more savvy about Blue Book car values than they are about their own homes. To the extent that they think about it at all, they’re likely to go for spot fixes based on a one-size-fits-all rumor like “I hear that radiant barriers are cool” instead of taking a wholistic approach. A minority of homeowners are DIY energy nerds, who cheerfully experiment on their own homes and report the results, successful or not, for the sake of knowledge sharing alone.

“The MLS real estate listing service does not yet include third-party verifications for any green building programs, so it’s hard to tell exactly how much more the same home would sell for – or how quickly,” said Rich. Rich cited a Portland study claiming an 18% premium, although he personally thinks that 10% is a more reasonable assumption to make. “People want a green home, but they don’t want to pay more for it,” he added. Sometimes green homes sell more quickly, which can be a big advantage to those looking to recoup their investment.

The value of the LEED brand was discussed. A GreenPoint Rated home can have a score anywhere from around 50 to 300 points – but GreenPoint Rating is only within the State of California. LEED has better nationwide brand recognition, and its three designations – Silver, Gold, and Platinum – are simpler to understand, even if the process to achieve them isn’t.

I’d also hazard a guess that homeowners who’ve actually been through the process or who have chosen to invest in the purchase of a LEED certified or GreenPoint Rated home are likely to be happier and more satisfied with their homes than people who are just looking for something affordable. “Most people hate their homes,” was the astonishing opinion of one HVAC engineer whom I met at a Title 24 class last fall. “If they spend any money on improvements, they want it to be something they can see, like a granite countertop.” Both LEED and GreenPoints are intended to create a home that is more comfortable to live in – less drafty, less noisy, and with better indoor air quality – and I’d guess that many people assume that a high level of comfort and control is out of reach, so they just learn to live with whatever they’ve already got.

Don’t Forget: Factor In Energy Savings

Lower operating costs should be factored in to the value equation as well, particularly energy savings. Both LEED and GreenPoints mandate energy-efficient homes – and they both give points beyond the minimum of 15% over “standard” (Title 24 in the case of California). The exact amount of savings will vary by project, and of course if you invest in renewable energy as well as energy retrofitting, the savings will increase. Don’t forget to factor in sudden utility price increases, not that those ever happen… right, Gray Davis?

It could be argued that one can build energy-efficient homes without getting them LEED certified or GreenPoint Rated. However, having a committed process to enforce a level of structure and rigor throughout the project can help guide decision-making and keep the team focused on the right goals. This is one point Ann Edminster makes in her book “Energy Free” – think about why you’re doing it and what your general strategy will be upfront, and then use it as a road map later on.

The other argument – namely that LEED certified buildings aren’t really more energy-efficient – seems to be based on outmoded assumptions. After reviewing the LEED for Homes criteria that include, among other things, requirements for demonstrated overall energy-efficiency (using the HERS index or, in California, beating the Title 24 energy code by 15%), and Energy Star rating, I don’t think it’s possible to go through all that and NOT have a more efficient building. There’s a whole other set of arguments on the counter-effect of efficient buildings actually encouraging more usage – but that topic will have to wait for another day.

Isn’t LEED for Homes Too Cumbersome?

The main critique of LEED for Homes, especially compared to GreenPoint Rating, is that LEED is cumbersome and inflexible. Why would anyone bother when they could just get the project GreenPoint Rated instead? That’s the California voluntary green building standard from BuildItGreen and it’s being adopted by many jurisdictions as a local requirement anyway.

I put this question out to one of our Green Compliance Plus affiliates, Rob Lehman. Rob said “I’d take GreenPoint Rated over LEED for Homes any day” and mentioned the following items:

• GreenPoint Rating is more practical, user-friendly, and affordable. There are a few mandatory measures and the rest are items you pick a la carte. So it can be less stringent but that’s up to you, how many measures you want to include in the project. Because the barrier to entry is lower, it’s actually more of an incentive to get owners to agree to go through the process. Most California jurisdictions that require GreenPoint Rating have reasonable score requirements, at least for now.

• GreenPoint certification is faster and everything goes through the GreenPoint Rater. The LEED application has to go through review in the D.C. headquarters of US Green Building Council and that alone can take up to a year. The USGBC doesn’t respond to questions that quickly, either.

• LEED is very strict and the process is bureaucratic and inflexible. You have to first get your “scenario” approved (by the D.C. central office) and then if you change anything later on, you have to get those changes formally approved as well. Rich Williams added another piece here. “LEED updates can be hard to figure out. Some of them apply retroactively to past projects, some only to projects done in certain years. But what do you expect from an organization that’s based in Washington, D.C.?”

• The LEED mandatory measures are costly. One example that Rob Lehman cited: LEED requires Energy Star certification, which has an extremely stringent quality of insulation inspection – a lot stricter even than the HERS QII credit. It involves a lot of extra sheet rock, building of chases, and even more site visits than a HERS QII inspection.

Rich Williams actually disagreed about LEED being too cumbersome. “Achieving a basic level of LEED is not that difficult,” he said. “It’s like riding a bike – really hard the first time, but then it quickly becomes second nature.” He sees the main challenge as one of training the production builders to be aware of the standard and to follow it. Still, he says it doesn’t make sense for all projects.

One Sustainable Architect’s Viewpoint

One of the other respondents who had an unusual and dissenting viewpoint was Dan Johnson of Arkin Tilt Architects in Berkeley. They’re just finishing a LEED Platinum house in Palo Alto. Although most of their projects are not certified in any rating system, they are nonetheless quite advanced: off grid, energy independent, passive solar design, renewable energy systems, water collection, extensive attention to sustainable material selection, minimal site impact.

“We prefer to build green without doing paperwork required by a rating system.  Since our future work is based on high performing buildings and client referrals, we already have an incentive to stay at the front of green design without cheating just to make claims. To reduce our clients’ costs, I’d prefer not to spend their money on administrative overhead.  Our name is our green brand.

“I would agree that LEED-H costs the owner lots of money in administrative time, proportionally more for smaller houses. The hours spent on paperwork and calculations do not add any real physical value to the home. The owner could instead spend these thousands of dollars on energy upgrades to the home to get better ecological value for the dollar.

Dan echoed a sentiment that we’ve heard from a few other people, namely, that voluntary certifications don’t do that much to save the planet because the bulk of construction projects will build to code but not beyond. In order to make a real impact of any magnitude, it’s the building codes that have to catch up, and the role of innovation is to prove the concepts, but that’s all it can really do.

“GPR and LEED can validate the work of innovators and help them market their products, but this hasn’t improved the quality of the bulk of new construction [which is mandated by code]. In the absence of high government standards for construction, the LEED award is useful from a consumer’s perspective because it verifies quality claims. However, since LEED-H is no longer very far ahead of the code [in California at least], even the marketing value is not there anymore.

“Now that we have CALGreen, the code minimum has caught up to LEED. It seems that fully of half of the credits in LEED-H are code-minimums now that CALGreen is in effect. So the argument against the usefulness of LEED-H certification has more weight this year. Do owners want to spend money on LEED-H documentation showing that their house meets building code? The cities already provide this service through the plan check and inspection process.

“I would like to see more green compliance handled through the normal code compliance pathway administered by the government, to reduce layers of oversight. It would make sense for LEED-H and GPR to go away, now that the code has caught up, or to raise their standards, to remain relevant as a high bar for innovators. In this regard, PassivHaus and the Living Building Challenge have taken the lead as the high bar for innovators to distinguish themselves. LEED has been so successful in California that LEED is now partially redundant with the building code.

“When a city requires GPR or LEED-H certification as the worst allowable construction, can the architect really take credit for “Leadership…” anymore? In lieu of these award systems, I would like to see HERS launched as a statewide mandatory energy labeling system; new homes are scored on the HERS index during plan check and existing homes are scored at time of sale.

Well, that blew my hair back a little. Both USGBC and BuildItGreen because have been extremely successful because they set a high bar. In California, that bar gets raised up every three years, and very likely these voluntary green standards will continue to improve as well. Sustainability is a moving target, one that every person on Earth will have to wrestle with at some point – on a global, national, local, and personal level – whether we want to or not.

Do’s and Don’ts for LEED for Homes

OK, I’ve recovered sufficiently from the boldness of Dan’s words to abstract a few guidelines for residential architects who may be considering whether to get a California home project “green” certified, either through LEED or through GreenPoint Rating. These notes would still be relevant for other certification programs as well.

• DO review local jurisdictional requirements before doing anything else. Some places require GreenPoint rating based on the sized of the house; others may adopt CALGreen tiers beyond the minimum. Or, they may offer expedited plan checking for certain programs.

• DO ensure that the owner is fully committed to the ideals of sustainability, and not just the label. Why are they doing it?

• DO plan for the chosen certification early, including an ongoing assessment of the impact that the certification may have on project budget and scope of work.

• DON’T forget to factor in any incentive programs that may be available.

• DON’T forget to list the intangible, non-monetary benefits of any sustainable measures. A correctly designed, high-efficiency heating system might cost more, but you’ll be more comfortable. Maybe a lot more comfortable. Ditto using low-VOC materials.

• DO Spend a few hours with a good green building consultant. Spend some time reviewing the required and optional measures in both sets of standards, and make sure that the mandatory measures are feasible and affordable for your project before committing to the whole process. At this point, the owners may feel that they have to choose between scope of work and certification – “If I get LEED certification I won’t be able to afford to do as much as I’d wanted” – so consider carefully how your clients’ money will be spent.

• DO read the manual. Both GreenPoints and LEED for Homes have handbooks describing their requirements in detail. The entire project team should know what the requirements are, and how they will be verified.

• DO try to build up some in-house knowledge of various green building codes and standards: CALGreen, GreenPoints, and LEED. If your’e inclined more towards LEED, get a LEED AP designer on staff if you can. Same goes for BuildItGreen – try to have someone who’s a Certified Green Building Professional, and who knows the GPR system well.

• DO partner with a good green builder – someone who’s worked on LEED or GreenPoint Rated homes before, and who can handle the paperwork.

• DON’T do it just for the label. Jonathan Feldman was emphatic on this point. “Don’t do things just for the points. Do things that you were going to do anyway. You’ll have a better product in the end, better quality control and better durability.”

• DO embrace an integrated design approach. Mitchel Slade, President of Eco-Struction, had some good advice for the entire team, including owner, architect, and builder: “Be malleable. LEED for Homes certification should be one continuous process, not a set of individualized tasks.”

This home in Atherton, CA, built by Eco-Struction, earned LEED Platinum certification.

Epilogue

There’s a lot of room for differing opinion, and no doubt some readers will find some statements above to be objectionable. There simply isn’t room to do full justice to every fact and argument in one blog posting. We encourage you to comment on this article and share your own experiences. All comments are moderated, so please use a valid email address, keep your comments directly relevant to the article, and please be sure that your message is respectfully worded. ;-0

Everything you think you know about insulation is wrong. That’s in a nutshell what I got from talking with James Morshead of SDI Insulation, Inc. in Burlingame, CA.  SDI is a full-service green insulation contractor offering “sustainable” versions of several common insulation types, including blown-in, spray foam, and fiberglass batts. I wanted to know about high-performing insulation products that would fit into small building cavities, because that’s often something we have to recommend for Title 24 performance modeling. But it’s one thing to say that a project has to fit R38 worth of insulation into a 4-inch roof space, and it’s quite another to find an affordable product that’ll actually do it – and where using that product’s self-reported rating is also acceptable for demonstrating Title 24 compliance.

Summary of the Problem

Insulation is one obvious way to make a home more energy-efficient. Sometimes, existing conditions may limit how much insulation can fit inside the wall, roof, and floor. The catch-22 is when a home needs a higher level of insulation than can easily be fitted inside the existing 2×4 frame walls, and a limited project scope won’t allow that shortfall to be made up elsewhere. In a remodel, retrofitting can be an issue; opening up too many walls could trigger a seismic analysis, and in other cases there may not be the budget to open up new areas.

But what’s the main standard for measuring insulation’s performance? In Title 24, it’s a measure called the R-value which measures the material’s resistance to heat transfer through a 1″ thick piece of that material. According to Morshead, it’s inadequate for the following reasons:

• It’s measured under unrealistically perfect conditions.
• It ignores the need for, and impact of, proper air sealing.
• It ignores the law of diminishing return.

What’s Missing From Insulation R-Values: Air Sealing and Installation Quality

Insulation products are measured in R-value per inch, and they vary widely, with typical fiberglass batt insulation around R 3.5 per inch. Fiberglass batt is the baseline because it’s so commonly used. It’s cheap, flame and pest resistant, and – if installed properly – it does a pretty good job. Two major assumptions that are built into Title 24 are that 1) you can fit up to R15 of fiberglass batts in a typical 2×4 wall, and 2) energy performance increases somewhat proportionally to the amount of insulation. Fiberglass batt insulation has other advantages: easy to install, affordable, fireproof, doesn’t attract moisture, mold, or termites.

But what if you’ve only got a very narrow gap inside the roof of an existing home, and Title 24 says that you need to make the roof R30 or even R38 to do your remodel? Well, one choice could be to go with a different type of insulation product, usually more expensive. But, if you really expect the insulation as actually installed in the home to live up to this expected rating, you will need to consider the factor of air sealing as applied specifically to insulation – and that’s something that’s not adequately addressed in the energy code, or even by insulation vendors themselves.

In many attics, the fiberglass batts are left exposed, without any kind of sealing on the inside. The insulation R value here would be greatly diminished.

This is where spray foam insulation outperforms batt insulation. Spray foam creates an air barrier whereas batt insulation, when left free and open as it is in many typical places like an attic, is as permeable as a mosquito net. “It’s a giant air filter!” said James. “It does absolutely nothing. Your R value could be less than 10% of what it’s supposed to be.”

This installation's a little better. The facing on the front acts as a vapor retardang. Presumably this project would also include a finish such as drywall or board applied flush against the batt insulation on the interior wall. If the builder really intends to prevent air from flowing through the insulation, further air sealing measures would be needed.

According to James, you can use spray foam at a lower R value than batt and still get better performance. [Wow… really?] “You have to bypass regulatory and industry forces that are pushing the R-value as the ultimate measure,” he said. “You have to take the position that you are seeking comfort and efficiency regardless of R-value”.

These two examples show how spray foam can be used to seal air leaks at joists or gaps, either as the main insulating agent or, on the right, in combination with other insulation types such as rigid insulation.

The First Few R-Values Are What Really Matters

The law of diminishing return implies that more is not always better when it comes to insulation. People may think that if R13 is the minimum, then R26 will be twice as good, and so forth with R30, R45, R60. “It’s the first 2 inches of spray foam that matter the most, or the first few increments of batt insulation R-value. There’s a sweet spot where you have enough insulation, and then you should spend additional money elsewhere,” advised James.

With insulation, it's the first few inches that matter the most. For any given climate, there's an optimal level beyond which it's not cost-effective to insulate further.

“At R10 – assuming ideal, airtight conditions – 97.9% of heat transfer is already eliminated,” said James [really??] “so why go to R25?” It’s because of the shortfalls in fiberglass installation techniques. “It’s like they’re saying, ‘Don’t pay attention to the physics, please.’ In reality, it doesn’t make sense to spend all that money chasing that last 10%, the way the Passive House people do. You can better spend your money elsewhere.” I can’t wait to hear the Passive House people screaming at that one.

Surface Temperature Control and R-Value

With insulation, what you are really trying to do is control the temperature of the interior surface of your wall, roof, or floor. James had a good analogy. “Imagine holding a paper cup filled with boiling water, and then imagine the same thing in a styrofoam cup. Which is easier to hold?” The styrofoam cup is a lot easier, obviously. But is R-value alone enough to account for this difference?

James offered a brain teaser for additional illustration. “Imagine a room that is 0 degrees adjacent to another room that’s 80 degrees, and your wall only has room for one inch of R6 insulation. It’s your refrigerator! And yet it obviously does work – why? Because that door stops air movement, which helps with controlling condensation.” Air movement within the building cavity can be exacerbated by a phenomenon called convective looping, as shown below.

One example of convective looping occurs when a warm but uninsulated interior surface heats cold attic air above, causing it to rise and circulate within a joist cavity. This in turn causes cold air to fall towards that warm surface. This example from BuildingScience.com shows actual air leakage from conditioned space into a joist cavity and back.

“R-value measures conducted heat in a bizarre test that is not reality. They take a 2″ thick sample and assume ideal conditions: that there is no air, no moisture, no convective looping – only conducted heat. It’s not the same as a real wall with gaps and air leakage. But we aren’t allowed to use terms like ‘effective’ R-value to distinguish among these conditions.”

(I found some good articles describing this phenomenon more in depth: one on wood pitched roof construction, and one on those ever-exciting floor-kneewall transitions.)

Air Sealing for Different Insulation Types

How you ensure airtightness depends on the type of insulation used.

• Spray foam provides its own air seal. One big advantage of spray foam insulation is that as it expands, it covers holes in the building envelope (such as openings made to accommodate electrical wiring or plumbing) with an air-impermeable barrier. Thus it can also be used prior to installing other insulation, to seal areas around joists, pipes, etc.

• Fiberglass batts must be air sealed on all 6 sides to be effective. “But that almost never happens in reality,” said James. Partly that’s because it’s very difficult to install fiberglass batts correctly, even for builders who’s love to do it perfectly. But here’s a good place to plug another great blog, Energy Vanguard, which has some great articles on just how tricky batt installation can be, including one on hidden air leakage sites in your attic and one on insulation and air infiltration

• With rigid insulation, failure to air seal on the inside can lead to condensation at the roof membrane itself. James responded to one of my questions with, “That’s where some of the horror stories come from. Someone stuck rigid in the roof and filled the cavity, but left it open on the inside so that interior air could flow around the rigid insulation up to the roof, which is cold – then they wonder why they’ve got water.”

• Blown-in insulation reduces air convection currents, and its advantage is, well, you blow it in till you fill the cavity. You don’t have to spend hours cutting and fitting every last piece, or ensuring a flush air barrier on all sides. And, you don’t have to rip the wall open, either.

Moisture

Allowing cold air to accumulate next to a warm but uninsulated surface also invites moisture and condensation to occur. In addition to allowing mold, rot, and deterioration, moisture ruins your thermal performance.

The accumulation of moisture inside a building cavity diminishes the performance of batt and cellulose insulation. Thermal images are a good way to detect water intrusion that's otherwise invisible, as shown in this infrared image of a flat roof. Moisture won't affect the performance of closed-cell spray foam as much, however.

The science of preventing condensation inside cavities varies by climate. The placement and use of air and vapor barriers is beyond the scope of this article, as is the topic of waterproofing (preventing direct water intrusion from the outside). For now we’ll just say that moisture affects some insulation types more than others.

• Cellulose or cotton batt will absorb the water directly, possibly leading to rot, plus the water degrades the insulation’s thermal performance.

• Fiberglass batt can absorb water even if the fibers themselves don’t swell, and the weight of built-up moisture can cause the instulation to sag, accumulate mold, or experience degraded thermal performance.

• Closed cell spray foams are vapor retarders and moisture resistant, although if water condenses inside the cavity somehow, it might affect adhesion.

• Open cell spray foam can absorb water from condensation in the air.

Ice Damming and Spray Foam

Snow melt is a special case that is less urgent in most of California, but I’ll mention it anyway. I was asking about some of the horror stories about spray foam and mold. James quickly leaped to the defense of spray foam. “It’s not the product, it’s the construction. Some of those horror stories involve insufficient R value or poor installation in snow load areas. R38 is OK for insulation against cold air alone, but in snow country you need R50 to keep the roof surface cool enough to prevent the snow on it from melting. The surface temperature of roof must stay below freezing to prevent ice damming. So, you can either ventilate the heck out of the roof, or you can use enough spray foam and ventilate the upper roof assembly instead.”

In snow areas, care should be taken to avoid "hot spots" on the roof that can cause snow to melt, re-freeze, and seep back into the house.

Ventilated vs Unventilated Roof Assemblies

James mentioned the possibility of an unventilated roof assembly with closed-cell spray foam. “You can do more cool architectural tricks with them.”

However, attics with ventilation are far more common, and James had a lot to say about them. “Conventional vented attics are energy sucks. A vented attic leaks heat both from the vents, and from insulation not being closed on all 6 sides. How many attics have you seen with the batts just exposed? All the summer heat goes into the attic, and while venting lets the hot air out, it does nothing about the radiant heat coming in. That radiant heat still transfers even with vents present, and that’s why so many attics are 130 degrees in the summer.”

“And all that vented air is moving over the open fiberglass. People say ‘I can’t get my house to cool off at night’ because the roof is still hot and it’s radiating heat into the interior.” Radiant heat actually radiates directly from the hot interior surface, even if the air itself is cold. “Radiant heat transfer is powerful force.”

“But if you move the building’s thermal envelope to the roof deck, with rigid foam or spray foam at the roof line, the interior surface temperature of the attic will be the same as the house.”

Moving the building's thermal envelope from the attic ceiling to the roof line helps keep the attic cooler.

Radiant Barriers and Cool Roofs

While not strictly “insulation”, radiant barriers also act to resist the transfer of heat from the roof into the home – specifically, solar heat gain. There are plenty of do’s and don’ts for these, starting with whether it’s even appropriate for your climate zone or not. James had a few suggestions: “Don’t put spray foam over a radiant barrier, because it won’t be able do its job. It needs an air space and a temperature difference. ”

James also noted that cool roofs can get so cold at night that they attract condensation, even during construction. But this should probably be a separate article.

Types of Insulation

James and I didn’t go through every possible type of insulation, but we did discuss some pros and cons of the main types. I’d refer readers to the Wikipedia article, which has a more exhaustive discussion of different types of insulation, their performance, and general pros and cons.

Fiberglass batt

Pros: common and cheap; doesn’t degrade; fire resistant; not a food source for pests or mold
Cons: If it’s not well sealed, dust and moisture can collect on it and then mold can grow.

“Fiberglass batt must be in contact with an air barrier on all 6 sides. It won’t perform if it has even one side exposed – too air permeable. If it’s not sealed, it’s just a giant air filter. To make fiberglass perform closer to its rated R-value is more labor-intensive. You need to do a very careful installation, and air seal it properly.”

Fiberglass batt insulation is one of the most commonly used insulation types, especially for homes.

Blown-in fiberglass or cellulose

Pros: Fills every crack. Denser, which restricts air movement. Provides an acoustic barrier. Simpler installation. Doesn’t require full opening of the building cavity. Non-toxic.
Cons: Not a full air seal; can be heavy on ceilings; can absorb moisture; settles over time.

“It’s OK for walls or attics, not so much for frame floors or roofs. It’s easy to install – for an open wall, you put a fabric blanket up on the wall and blow it in.”

Blown-in insulation can be a good choice for filling building cavities quickly and cheaply. Left: blown-in fiberglass insulation. Right: blown-in cellulose insulation.

Cotton batt

Pro: Its green appeal, being a recycled natural fiber. Fibers are non-irritating, unlike fiberglass.
Cons: Expensive; difficult to cut and fit. Moisture could be a problem if it gets into the wall. Not a complete air seal.

“They don’t come in standard sizes to fit a 15.5″ cavity. It’s 16″ wide and you have to cut it every single time. The manufacturers haven’t learned to size it for conventional building methods yet, and so it’s very labor-intensive to install. It’s a cool idea, and it feels green, but is it?”

Cotton batt insulation, or "blue jean insulation" is recycled and natural.

Spray foam
Comes in two types: closed cell and open cell. Difference is density. They both come with a liquid medium and an expander gas, which can vary as to what it is. Open cell is cheaper and not quite as insulating.

Pros: Airtight seal; closed cell is a vapor retarder and air flow retarder as well. Relatively high R value for the size.
Cons: Expensive; needs an experienced installer; requires fire rated barrier; toxic during installation; may emit toxic gases during a fire; keep away from direct sunlight and solvents.

Spray foam insulation creates an air seal. Shown here is low-density spray foam.

Rigid insulation

Pros: Same high thermal performance as spray foam. Can use on exterior wall, roof, or under-slab to control thermal bridging. Good for high R values in small spaces. Water resistant; can be used for foundation and under-slab insulation.
Cons: Requires air sealing to prevent air movement through the cracks; requires skilled installation and construction techniques to use; expensive; keep away from sunlight and solvents; may emit toxic fumes in a fire;

“Construction techniques are harder. Different jamb sizes and flashing. More cutting and fitting required. It’s harder to put in wiring afterwards, because you have to cut into the board.”

The term "rigid insulation" covers a wide spectrum of products. Left: sandwich of wood fiber and polystyrene. Center: phenolic foam board with foil backing. Right: Application of rigid foam panels as foundation insulation.

Best Bang for the Buck

After going on at such length about the virtues of spray foam, James did have a few good words for fiberglass batts, too. “You can achieve almost the same level of comfort with batt if you do it right, and youdon’t leave gaps or air leakage to create drafts. The surface temperature of the wall on both sides is important too. If a wall is cold, the home is less comfortable – not only because of lowered air temperature, but because of radiant heat loss as well.”

How “Green” are the Foams?

I asked James a few general “green” questions, since many of our Title 24 clients are interested in the larger issues as well as measurable energy performance. So how “green” is each type of insulation? Aside from the fact that using insulation at all is better than wasting energy, the “green” question could be addressed by looking at a number of factors:

• Whether off-gassing will somehow affect indoor air quality for the occupants

• Toxicity during a fire, even for materials that are themselves flame-retardant

• Global warming, could be result of ozone-depleting gases either during manufacture or after installation

• Energy used in the manufacture and transport of the materials, both amount of energy used, and whether it comes from fossil fuels
• Whether the insulation products themselves are made from petroleum by-products

• How much energy is saved over the lifetime of the building

Aside from cost and efficiency, some of our clients have voiced other concerns, especially with toxicity. It’s ironic that being “green” and reducing energy use might involve the use of toxic materials, but that’s one thing that could happen. Fortunately, it’s not inevitable, although some care should be taken when selecting individual products within a category.

How Green is Blown-In Cellulose?

Cellulose is “kind of green”, according to James, having a high recycled content. It does have some plastics, and printed paper with “unknown inks” although it seems farfetched that the ink on recycled cellulose insulation would have much of an effect on indoor air quality. Fire toxicity, maybe… but building a fireproof home is a different goal than making an energy-efficient one, and at some point you have to make choices about priorities.

Are Spray Foams Toxic?

James didn’t think that even the spray foams were toxic to people. “Not many products are toxic for indoor air quality,” he said. “A lot of that perception is just the industry players fighting each other – fiberglass vs. cellulose vs. foam – and promoting disinformation about the other products. The real test of whether something is sustainable is to ask ‘What will my grandkids think about what I’m doing now?’ What’s the impact on the environment, on the grid, and on quality of life?”

(The Wikipedia article on building insulation materials doesn’t completely back him up on this. First off, they contain petrochemicals. Second, they have to be correctly mixed in the field in order to “cure” correctly, and the installers must wear protective breathing apparatus. Third, some of the agents used, while not harmful to the ozone layer, are greenhouse gases. However, despite some reports of chemically sensitive people having a bad reaction to it, spray foam is still the insulation of choice for many green builders, and can be used in combination with other insulation products especially for air sealing.)

Both spray foam and rigid insulation can be made from a huge variety of substances, even soy, although even the supposed soy-based ones are still mainly petrochemical. Not being a chemist myself, I can’t discuss the issues particular to each: isocyanurate, isocyanate, polyurethane, polyicynene, cementitious foam, polystyrene, CFCs, HFCs, HCFCs. As with many other areas, one recommendation is to select a good builder who is familiar with installing the type of insulation desired – and in your climate area. Chemically sensitive people may want to evaluate samples prior to applying it all over their home, since it seems like some of the worst experiences are from do-it-yourself types or from improper installation.

Improper installation can also include poorly designed wall assemblies that permit moisture buildup. This can lead to toxic conditions if mold occurs, apart from any toxicity in the materials themselves.

Forget About Certifications – Just Save Energy!

It’s really the energy reduction as applied to many homes, not just one or two showcase LEED places, that will have the greatest impact on Spaceship Earth, asserted James. “LEED, Passive Houses, and Net Zero are playthings of the rich,” he opined. “If multiple homeowners spent a fraction of that on their own homes it’d do a whole lot more than one or two ultra-efficient showcase homes that no one else could afford to build. Even for the average home, a 30% reduction in energy use is achievable almost with your eyes closed. And, that 30% savings requires some mental energy in terms of good integration of systems and good choices.”

I pressed him about the Net Zero remark, and it’s the obsession with certification that he thinks is overkill. “Anyone can follow the Net Zero method and improve their home, or build using Passive House techniques. It’s not always worthwhile getting that last 10% of the way there for full certification.” I said that having a zero energy bill for the year was not a “plaything of the rich”, and James responded with, “My clients care more about budget and comfort than about what awards they’ll get.”

He also said, “These showcase homes are like concept cars. Maybe in another generation they’ll be the standard, but for now, it’s better to concentrate on the average home than on a few visionary early adopters.” While I agree that energy efficiency should be accessible to the Teeming Millions, I also think that early adopters are extremely important, because their homes are more than concepts – they’re long-term experiments that will ultimately prove (or not) the proposed concepts. And so what if they don’t work? That’s part of the risk of the experimenter, is to learn the right lessons from failure so the next attempt works better.

Since he spent lot of time bending my ear about the deficiencies in Title 24 itself asked James what he thought should be in the prescriptive performance standards. He responded, “Airtight construction, correctly installed insulation, and correctly sized HVAC systems. An average house should have all this without special consultants or green certification.”

Antiquated Standards

"California's Title 24 energy code is like using a whip and buggy to measure jet-engine technologies," says James Morshead, Senior Project Manager and Building Science Director at SDI Insulation.

“The current rating system for insulation is completely antiquated,” said James. Well, as a vendor, he’d probably want to make that point regarding his competitors. In fact, he did say “There’s a lot of disinformation out there, and much of it is due to industry competition. The fiberglass guys try to dismiss the spray-foam guys and vice versa.”

James wasn’t shy about critiquing Title 24 as a standard, either. “What ends up in the code can be largely political,” he said. “That’s why the Title 24 Quality of Insulation Installation credit recognizes closed cell spray foam insulation, but not open cell foam – at least, not yet.” (The QII test evaluates the quality of batt insulation installation, and it must be performed by a HERS inspector.) He went even farther than that by saying, “Title 24 can often a hindrance in highly innovative building envelope designs, because it focuses on numbers on paper without consideration for what actually works, or for cost. However, it does encourage overall improvements in the majority of typical projects, which is its intended purpose.” He’s right about the lag time. The code can’t keep pace with new developments, and often a newly invented measure that offers superior performance in the real world won’t always comply with what’s already in the code. It simply takes time for codes to be re-evaluated and updated to account for these new technologies. In those cases, it’s often up to the local building officials. “But they also have less leeway than they used to,” said James.

About a year ago, we published an article about an exceptional Title 24 project – an astonishing 50% over compliance – and now we present an interview with the homeowner who commissioned the design. The single-family home, designed by Klopf Architecture, is currently under construction by Matarozzi Pelsinger Builders (As an aside, we’ve done design interviews with both Klopf and Mat-Pel on our sister blog, The Architect’s Take.)

Many residential architects would like to design homes as energy-efficient as this one, but without client buy-in, it’s usually not possible to go beyond a certain point. Over and over, we have heard that client commitment to sustainable principles is THE key to building green! So, here we have a green homeowner and design client who’s willing to discuss – anonymously – why he’s doing as much as he is, and why it’s worth doing.

What is your background, education, current profession?

My educational background is in human and computer languages, among other things, plus an MBA in global business practices.  I have run companies in two countries, and am currently advising startups on product and marketing strategy. I also do volunteer work for environmental nonprofits.

My wife’s educational background is in art plus an MBA.  Her artwork has been exhibited in galleries and museums, and she is currently an art educator.  She also does volunteer work for local schools and community events.

How did you become interested in sustainable design?

I have had a lifelong interest in cleaning up the environment and reducing dependence on foreign oil, and was first moved to take action on both at a very young age: in 1973! My wife also has a strong interest in doing the right thing in these areas, and we were both deeply impressed by just how bad an environmental situation can get based on what we saw while working in China.

What did you do in 1973? I remember at that time we turned our heat way down.

In 1973 I found out that a proposed nuclear power plant was going to endanger the fish in our main river with its cooling exhaust.  I joined my middle school “Ecology Club” where I learned even more about nukes, and volunteered to set up petition tables to gather signatures outside of supermarkets.   Also that was the year of the first OPEC oil embargo. With another group I walked the long gas lines handing out pamphlets promoting alternative energy independence.  Learned about all of this stuff by myself; my parents didn’t quite know what was going on.  Of course, those were the days when parents just turned kids loose on the streets while they did their own thing.

This green design client worked on his own initiative as a middle schooler to protect local fish from the cooling exhaust of a proposed nuclear power plant.

Have you experimented with any sustainable projects or home improvements in the past? How did those turn out?

We previously renovated an Eichler home, raising the energy efficiency and overall comfort of the house as best we could, but there is a limit to what you can do without a complete tear-down.  In the process we also developed a deep appreciation for mid-century modern design and 21st century home building techniques.

Have you compared notes with friends or others with similar interests? I think having a knowledge sharing group is important to keeping the flame alive, and if you’re a real hard-core do-it-yourselfer then technical notes might be essential to completing a new project. Of course a lot of that is online now.

Lots of information sharing going on.  A couple friends are renovating on tight budgets and acting as their own general contractors, but are very interested in as much energy savings and solar tech as they can pack in there.  Another guy we know is actually a professional in a technical area of green building, and for their new home he has an architect and contractor putting up a shining example of what’s possible in both architectural and energy design.  Also many neighbors are following our project with great interest, including an electric power researcher who lives right across the street, and our example may influence plans for at least small aspects of many future projects.

I have participated in our local city’s green building ordinance focus group, I’ve had good discussions with green building advocates on the city planning commission and staff, and I’ve even tried to help educate one or two commissioners and other local leaders who don’t seem to have all the facts.  City staff have followed our progress with great interest, and even PG&E has been very supportive.

The green design client is also having the new home be GreenPoint Rated, and used the GreenPoint Checklist as a guide to adding more sustainable features during the design stage.

Apparently, after quite a bit of internal discussion about our project, PG&E decided to get out ahead of the looming challenge of upgrading the grid for electric vehicles (EVs). Instead of waiting until we purchased EVs and chargers that don’t even exist yet – which would have required all sorts of rewiring and reengineering inside and outside our house – they gathered all the information we and the EV companies could provide, and decided to future-proof our entire block by upgrading the transformer, wiring and power poles. They used our project as a benchmark for internal research and planning, and I believe our project may have contributed to PG&E’s most recent guidelines on electric vehicle interconnections for your home.

What made you decide to hire an architect and go for a custom designed home instead of just buying something already built?

We will get more value out of our custom designed home than most people.  The house will seldom be empty, so the return on investment for every energy saving measure is very clear, and the beautiful design will make it a pleasure to live there too!  We will both live and work in the house, we have young children and frequent guests, and we don’t plan to move again.  Our architects have helped us design a home that fits our lifestyle and our long-term plans, and having control of all materials in a complete new custom project allows for better health and energy results.

The same firm that designed the high-performing green home discussed in this article, Klopf Architecture, also has experience with Eichler remodels. Shown here are two of Klopf's other Eichler remodeling projects. The renderings for the green home have a similar airy, open feel.

The whole ROI discussion is a big deal, especially how it’s calculated. The bottom-liners might say that adding green features doesn’t necessarily add to the resale value of the home (as if that’s the only reason to do anything), and they don’t seem to consider long-term savings in energy bills. Without making this discussion too dry to read, I wonder if you could expand a bit more on how you figured your financial return, over what length of time, in a way that makes it seem comparable to other investments people might make over their lives.

It’s an accepted rule of thumb that a new solar PV system adds roughly $20 in value to your home for every $1 saved off your utility bill.  In our case that pencils out to about 20% more than the full cost of the system, *before* rebates and tax credits.  After those are subtracted it’s over 50%!  I know rebates and credits plug some people in, so to speak, but you can’t have it both ways: either kill all the many tax breaks, subsidies and other support for the oil and gas industry too, in which case the price of gasoline would average $10 a gallon, or give the alternative energy and electric vehicle industries a little support so we can transition the economy more gently while pursuing long-term national interests. In fact, government support for these new industries is dwarfed by what the multinational fossil fuel corporations have negotiated for themselves, it’s absolutely obscene.

Which would you rather have: an oil-dependent economy, or the ability to breathe freely?

As for energy savings from other aspects of the house, since we exceed Title 24  by 50% to 60% the return is very clear and faster than you may expect. The new house is three times the size of the old one but requires almost the same amount electricity, and will use no natural gas unless I connect it to an outdoor bar-b-que.  Yes, all this efficiency costs more, and I’ve had several people I don’t know walk up to me in front of the half-finished house and just out-and-out ask “how much per square foot?”  They don’t get the answer they expect.  I point over to a new stucco show-off McMansion around the corner and say “I guarantee you I’m spending more per square foot than that one.  But I’ll be earning it all back on my utility bill, and then some.”  And if another Enron-type power crisis or OPEC embargo comes around again, the ROI will arrive even faster. They all seemed to go away thinking hard about their priorities after that.

Many people don’t seem to value the energy upgrades that actually give them the best bang for the buck, with or without the public statement of a PV system.  (Speaking of which, we tried to hide our panels as much as possible.) Our system would not be paying for itself in about eight years if it weren’t for our commitment from the beginning of the project to a high GreenPoint rating, but in the end that makes our system a better value.

There are slew of sustainability approaches, yardsticks, and standards: GreenPoints, LEED, zero carbon, embedded energy, biodynamic agriculture, slow food, etc. More coming out all the time. What’s your personal philosophy on sustainability? What do you feel is most important and why?

GreenPoints, LEED, Title 24 etc. are important as objective third-party “yardsticks” because all of this is new and changing almost daily.  Everyone in the business is still learning, and hiring a “Certified Green Builder” is just the beginning.  There are good business reasons for these standards.

My personal philosophy on all this is based on a businesslike approach too, beginning with the realization that using language like “sustainability” simply puts many people off. To really serve as an example and make a difference in this world, a successful approach to green building must appeal to more people at all level of needs and aspirations, starting with the most fundamental personal and economic issues. Otherwise it’s just a few of us making these changes, and overall the world is still going down the tubes.

The fact that we’re getting a good financial return on investment in this project is the best way to start neighborhood and national conversations on long-term energy, environmental, economic, security and foreign policy goals.

What is most satisfying about your new home (still under construction)? Not just green, but the “home” part of it too. How’s this home helping you realize your personal dreams?

Well, at the most basic level, it will be a drastic and satisfying change to live in a home that stays warm when you heat it, stays cool when you cool it, and saves money doing both.  But intellectually the most satisfying thing for me is the idea that this house, totally independent from fossil fuels and prewired for electric vehicles, will contribute to national security, peace in the Middle East, and a cleaner healthier world for our children. Emotionally, there will be great satisfaction in a custom home designed to support deep integration of work and family life, exactly the way we live it.  And, it will just be a darn nice place to live.

We are pleased to announce that Mark English, AIA, principal of Mark English Architects, has earned credentials as a Certified Energy Plans Examiner. This program is administered by the California Association of Building Energy Consultants (CABEC) to provide an objective demonstration of a person’s technical expertise and application skills for the California Title 24 Energy Standards.

Why is this exciting, you ask? Well, you don’t need CEPE credentials to prepare Title 24 compliance reports, but some incentive programs such as the New Solar Homes Partnership (NSHP) from the California Solar Initiative require that the Title 24 report be prepared and signed by a CEPE in order to be considered eligible. To achieve this certification requires a class and a 2-hour exam, administered by CABEC.

The California CEPE training and certification program is administered through the California Association of Building Energy Constultants (CABEC).

Of all the green building guides for homeowners out there, here is one that should be on everyone’s shelf – owners, architects, builders alike. It’s called “Energy Free: Homes for a Small Planet” by Ann V. Edminster, a Bay Area local. Everything I’ve been struggling so hard to explain to our Title 24 clients, even in a limited way, is presented in this book with clarity and accuracy, in a very readable and lively prose style. It’s backed by both the latest research and by personal experience and observation.

The Problem with Mantras

“They want it to be ‘green’…” Neither the client nor the architect had any comprehension or appreciation of “green” other than as a gimmick. The client was an Al Gore fan who had read “An Inconvenient Truth” and suddenly decided mid-design that the new house being designed for him and his girlfriend needed a “zero carbon footprint”. There had previously been vague feel-good conversations about “eco” and “green” but nothing tangible, no specific goals, performance measures, or standards to follow. Unfortunately, neither the client nor the architect understood how much work “zero carbon” actually entailed, and the client hadn’t selected this particular architect for his expertise in green building. He had originally envisioned a luxury home by a “design-oriented” (i.e. Modernist) architect.

"Green zombies" chant the green mantra endlessly, but never stop to think about how to get there.

I can’t tell the whole story here, but it seems that the client was shocked to hear that there might be re-design fees involved, plus a fair amount of additional research. (He and his girlfriend split up in the middle of the project, too – the project was subsequently abandoned.) Perhaps he felt that anyone calling himself an architect should already have the answers. That’s a bit like saying the architect should already have the house designed the moment you set foot in their office.

First, Take A Good Look in the Mirror

But choosing green can be daunting – as if shelling out several hundred thousand dollars or a few million for a custom-built home isn’t daunting enough. If you’re seriously trying to be green, there are so many competing standards and methodologies out there, it can seem overwhelming. And to be honest, there is no shortcut to thinking hard and seriously about it as an owner. You’re not just learning about technology, you’re taking an inventory of yourself, your habits, the real implications of those habits, and what you could do without. It’s also being very honest about what you can’t live without and sticking to your guns about it – even if that need might seem “selfish” rather than “green”. You can’t just engage with an architect, wave your hand like Captain Piccard on Star Trek: The Next Generation, and say “Make it so.”

The hardest work of green design is asking yourself what's really important, and then following through

What we need is a simple guide on HOW to think about building green, meaning how do you go about deciding what your priorities are and then executing them to completion? How do you even define what’s green, or green enough? What kind of science is behind each of the green definitions, anyway? It’s an exercise in complex problem solving – and self-analysis.

Start With Home Energy Consumption

Measuring greenness according to energy consumption is fairly straightforward, and while that can’t capture everything related to embedded energy, building life cycle, etc., it is the sort of bottom line that anyone who can balance a checkbook can understand. And finally, we have a book that talks turkey about how do we get from being energy-dependent to a point where we’re more in control.

“Energy Free” manages to provide clear guidelines without being too dogmatic about any one thing. Edminster’s focus is on energy efficiency as a means to reducing our dependence on oil and other fossil fuels. Along the way, she exposes a lot of myths and misconceptions about what it really means to produce your own energy instead of relying on “the grid”. Although this approach is sometimes called Net Zero, she prefers to call it energy-free, because you’re freer, more liberated (to a point which YOU determine).  It’s both a manifesto and a guidebook for creating and enjoying a net-zero-energy home.

Determining That Net Zero Point

The first debunking is to explore what NZE means. For example, producing as much electricity as you consume onsite doesn’t take into account transmission losses from the power plant to your house. Also, you have to use different conversion ratios depending on the type of fuel you use (electric, gas, propane). In the case of electric power, the type of fuel used at the power generation plant can affect how “green” or “wasteful” that electricity really is. This forces the owner to confront his or her own principles at the get-go. How far are YOU willing to go and what will you get out of it?

Then there are practical questions about Net Zero. Will it actually save me money? Can I use the same builder? What are the real-world pitfalls and how do I avoid them? How do I manage the project? Who needs to be on the team, and when? Edminster does a superlative job of capturing the key drivers and human factors that can make your NZE project a success.

No One-Size-Fits-All Solution

Our culture of instant gratification and ever-shrinking attention spans does not lend itself to complex, thoughtful, tailored solutions. But, after clearly defining your principles, goals, and budget, the next thing you need to do is realize that every solution is local and is dependent on context. What works in San Diego may not make sense in San Francisco. And, concerns that are important for surviving a Massachusetts winter might not matter in San Jose.

A radiant barrier won't help as much in Tahoe as it will in Death Valley. Different climates call for different measures.

Edminster’s approach is to treat it like a team science project, and to keep everyone focused on the performance goals. It’s one thing to say that passive solar designs are nifty, but it’s better to start with some specific goal (and location), and then identify all the different ways one could achieve that goal. KNOW what your goals are, and be prepared to read the fine print – like which measures actually make sense for your climate zone. But don’t forget your personal goals, or you won’t be happy with the end result. A happy home takes more than just low-flow showerheads, and everyone on the team should appreciate this fundamental notion.

Your Team

This is something that other Green Builders have said, but it’s worth repeating, since we say it to our Title 24 clients as well. If you want a high-performing home, think farther ahead to make the best design decisions possible, and get your experts all talking to one another during the early design stages. And don’t use a compartmentalized series of handoffs, which unfortunately is the standard way of doing business in the homebuilding and home remodeling industry. Make sure your team members can work well together (that includes you) and that everyone starts on the same page. This is referred to as “integrated design”.

Green building requires a long-range planning approach, rather than a moment-to-moment response.

The skill sets are also different. A typical, non-integrated team might have an owner, a builder, and an architect. Other consultants might be brought in as needed but they have limited influence over design elements not in their immediate purview. They probably don’t have any visibility, either.

A compartmentalized, "handoff" approach might look like this Gantt chart.

In addition to the owner and builder, an integrated team might have a mechanical engineer, an energy modeler, possibly a structural engineer, and a renewable-energy vendor. All of these individuals need to be part of the initial design process, so that they can understand the wholistic impact of each proposed design element – and the reasons behind that impact.The team must have a clear common understanding of the goals of the project, in order to determine whether a particular impact is acceptable or not.

Start by Scoping Down Energy Needs

It makes sense once you hear it. Minimize the home’s energy budget before sizing any renewable energy systems. You do this by a multi-pronged approach that includes building, appliances, and occupants. The building should be efficient and not oversized; appliances should be not just Energy Star rated, but top of the chart; and occupants should be educated on things like how much energy a plasma TV REALLY uses.

Downsizing on floor space might be a hard pill for some people to swallow, but it’s really only going back to what homes were like in the 1950s, when the average was 292 SF per person. Now, it’s more like 961 SF – a threefold increase. Do we really need that floorspace? Or could some of it be outdoor space, or transitional space that doesn’t need conditioning?

This rather cramped attic is actually from Lawrence Welk's childhood home. A far cry from McMansions!

This Time, You Should Sweat the Little Stuff

Next come the appliances, lights, and electronics. What can you scope down or trade for a more efficient model? What can you eliminate? What energy management systems are there to monitor usage and to shut off appliances when not in use? What about water heating? Do you need that spa, or would a compact steam shower do almost as well?

Almost every item in the house offers opportunities for reduction, from faucets to lighting fixtures. For energy nerds, the lengthy discussions of just how much extra energy is used by the heating element inside your dishwasher will be glorious. But actually, everything discussed is in response to frequently raised questions about things like whether a measure really saves resources or not.

The section on building efficiency goes on for pages about different types of insulation, but even better were the detail sections showing sheathing, insulation, and airtightness. Everything from mold prevention to stack ventilation to solar heat gain. Without playing favorites, there’s a huge section on heating and cooling systems and how to get the most out of each type. There are even piping diagrams for hot water delivery.

But the best thing? An energy-modeling chart showing how the influence of different building parameters changes by building type and climate zone. For example, window area and solar heat gain was more important on the “urban” single family home in Palm Desert, but of lesser importance on a low-rise detached home in San Francisco. Surprisingly, building orientation did not have as much of an effect as one might think, except for the urban home in Palm Springs.

Living Patterns and Appliance Use

One thing I liked about the chapter on integrated design was the emphasis on behavioral factors and living patterns. For example, an owner who is away from the house much of the time might have different preferences than someone who is there all the time. Some owners may be willing to change their behavior or their tolerances as well. For example, foregoing heavy air conditioning in favor of the old Mediterranean tradition of afternoon siestas, or wearing a sweater on chilly mornings.

Putting on one sweater on a cool day might be better than immediately turning up the heat. But, if you have to wear a parka and frosbite protection indoors, the house is probably too cold.

As with HVAC systems, the discussion on appliances and their use is exhaustive. Everything from induction cooktops to dishwashers (including when to hand wash and when not to), gardens, gadgets, and monitoring systems. The only thing missing was the obligatory rant on the mercury toxicity of CFLs. (I personally feel OK about them – I can see better and they cost so much less to operate than my favorites, the halogens.)

Quality Construction

Even the fanciest windows won’t save as much energy if the builder does a poor job of installing them. The same applies to everything else: walls, systems, plumbing, ductwork. Each part of the whole should be optimized and well-crafted. Unfortunately craftsmanship is not a given for all builders, although they’d like you to think so.

Post Construction Verification

Much of the information presented in this book came from the author’s direct experiences. Just because an energy model predicted a home that uses 25% less energy, does that mean that the actual owners will use less energy once they’re living there? What if it’s too hot, or too cold, because of some factor or complex interrelation of factors unique to the site? What do you do then? Usually, with good planning, remedial measures will be minor, and can be anticipated, to be used only if needed.

Please note that we have no commercial interest in promoting Ann Edminster's book "Energy Free" - we truly think it's a great guide to planning your home energy strategy.

Don’t say we didn’t warn you. The new Title 24 is tough! In past articles, we harped on the HERS verifications as a way to earn credits towards Title 24 compliance for those hard-to-pass houses. However, there’s another angle that needs attention: issues for additions, alterations, and remodels.

(Above image shows a whole-house remodel and addition by Mark English Architects. Photo: Michael O’Callahan)

When does a remodel need to show Title 24 compliance?

When the changes impact the exterior building envelope, the heating/cooling/water heating systems, or when you’re adding conditioned area or volume. Envelope changes include new walls, replacing windows, and adding or enlarging windows. System changes include upgrading a furnace, changing the type of heating/cooling system, re-doing the ductwork, or upgrading the water heater. There are other circumstances like changing the lighting that may require Title 24 compliance. The focus is on conditioned space only, so garages and sun porches are not counted.

When do you NOT need a Title 24?

When all changes are internal and don’t impact the energy performance of the building. For example, if you move a group of interior walls but leave the furnace alone.

What are the methods of showing compliance?

There are two main methods: prescriptive and performance. The prescriptive method works just like a doctor’s prescription, with mandatory minimums for things like insulation or glazing performance. We do a little of that, but much of the time it’s fairly simple and many architects just do it themselves. The downside is that it’s less flexible – there are minimums, but it’s harder to get credit for exceeding those minimums in some areas in order to make up for shortcomings in others.

Not all remodels will qualify for prescriptive compliance. For example, if glazing is more than 20% of the floor area, or more than 5% of the glazing is on the west, then the project may need to use the performance method. The performance method is what we do, using a CEC-approved software modeling program.

How do I know if my project can qualify for the simpler prescriptive method?

You can use prescriptive compliance if your project matches all of the features listed in Table 151-C of the Title 24 Residential Compliance Manual, which vary by climate zone according to the 16 climate zones of California. (The Bay Area is mostly Zones 3 or 4 with some 2 up north and 12 out towards Sacramento.)

The prescriptive baseline values used for most homes are also known as “Package D”.

What is Package D and where can I find the documentation?

Package D appears to consist mainly of this one table, (Table 151-C) plus several pages of footnotes, which is tucked in the back of the Residential Compliance Manual under Appendix B. Even here not all the information is included; the table just says “MIN” for furnace AFUE for example.

What does the prescriptive method require?

The following is a very simplified summary. For areas like San Francisco, East Bay and the Peninsula, wood-frame walls must be minimum R13, raised floors R19, and ceiling/roof R30. Glazing U factors must be .40 or lower, gas furnaces .78 AFUE or higher, and air conditioners must be SEER 13 or higher.

The prescriptive method places strict limits on the amount of glass that you can add, especially on the west. For additions from 100-1000 square feet, glazing must be less than 20% of the conditioned floor area – no curtain walls, sorry. If you have an addition that is under 100 square feet, that portion can’t have more than 50 square feet of glazing. If the project is an alteration and no area is being added, glazing can’t be more than 20% of the total conditioned floor area. Some climate zones also specify that only 5% of the total glazing area can be west facing.

Medieval castles like this one had very low glazing-to-floor-area ratios.

So, if you want an addition with a glass curtain wall for your Esherick home, you will have to use the performance method.

I wasn’t planning on opening all the exterior walls. And I was going to reuse my old windows, too.

Don’t count on being able to reuse the windows unless they’re of fairly recent vintage. If your existing windows are single glazed, or clear glass instead of low-E, or they’re metal framed instead of wood or vinyl, you can forget it. All windows leak heat, but old ones leak a lot more. Keeping those old windows could easily double the energy budget for the entire home, which would kill your chances for Title 24 compliance.

For additions, alterations, or remodels, where only some walls, windows, or existing systems are upgraded, Title 24 allows several possible approaches or strategies. Again here, we’re talking mainly about the performance method, but these strategies are also available for the prescriptive method as well.

Obviously we can try modeling the project using the old windows, but we’ve ended up having to include a host of other measures to compensate – things like upgrading to a more efficient furnace, HERS-testing the ductwork for air leakage, even adding thermal mass.

What’s a HERS test?

Most of you know this by now, but HERS tests are third-party field inspections for things like duct leakage, and you can earn “compliance credits” for these tests when using the performance method to show Title 24 compliance. Running the software model with one or more of these tests specified can improve the score of the proposed design, sometimes dramatically. They require additional coordination during construction, but are not as inconvenient as having to spend an extra $15,000 on new windows.

For more details, see our recent article on HERS inspections and Title 24 compliance.

What’s the difference between modeling an Addition Alone or doing the remodel as a Whole House?

Additions can be modeled as self-contained if conditioned square footage is being added, the new space is all in one spot, and for modeling purposes it’s best if the addition is at least partially sealed off from the rest of the house. As long as you insulate all those walls, including new interior walls, and use efficient windows,  you can model this additional space as its own self-contained little building. This means you can keep the crappy windows in the rest of the house.

This proposed addition adds square footage and uses new windows, while the rest of the house is left un-altered. This project could use Addition Alone compliance method.

However, if no square footage is actually being added, then you can’t show compliance for only one corner, even if that corner is getting the royal treatment. This can happen if, say, a family room is getting a facelift and new windows, maybe bigger windows than before, but it’s staying the same size as before. At this point you have to either meet the mandatory minimums for the altered portion, including maximum glazing-to-floor-area ratios that may apply to the entire building, or you have to use the performance method, meaning you have to model the entire project within one of those approved software programs mentioned earlier.

It also happens sometimes that the Addition won’t pass by itself. If we have to use the performance method because of glazing area or whatever, we can try running the addition by itself. However, sometimes even the most thoroughgoing modeling efforts will not yield a passing score. Then we have to model the entire building (or condo unit) – and for that, we need to include information on all the existing exterior surfaces: walls, roof, floor, and windows. If the existing conditions are unknown, we have to assume the worst, based on when the house was originally built.

This proposed alteration is not adding new floor area. The main work is occurring towards the rear, including new windows and walls. However, there are also new skylights being added elsewhere in the house, and the front window is replaced with two new windows. This project would require the Whole House compliance method.

How does the Title 24 modeling software show a pass or fail score?

What the software model does is compare energy usage of the proposed design (your remodeling plans) with the energy usage of that same house assuming the mandatory minimums. Model inputs include the home’s compass orientation, wall areas, floor areas, roof areas, glazing areas, actual systems in place, and performance numbers for each. For example, a 1,200 SF home oriented at 90 degrees east might have 270 SF of north facing exterior wall insulated anywhere from R0 to R25. This would be compared to a 1,200 SF east facing home with 270 SF of north facing exterior wall insulated to the minimum, R13. Your design has to beat this baseline, shown in this energy use summary as the “Standard Design”.

This sample Title 24 compliance report shows energy usage breakdowns separately for heating, cooling, and water heating. If the house is not passing, it's easier to see where improvements should be made first.

I really don’t want to open any more walls or replace more windows, because that will put us way over budget! My clients will go ballistic! Why can’t we just add more insulation to the parts that are being opened?

If you have to model the whole building, then all the existing conditions have to be modeled as they are now. This means that if any of the existing walls are un-insulated, that house is going to have a very hard time passing the software model, even if the rebuilt portions are insulated far beyond the minimum.

It is sometimes possible to use blown-in insulation for existing walls without having to open them completely. We have found that even minimal insulation of all walls is far better than leaving any portion of the walls at R0.

So it’s not passing, what do I do?

At that point it’s a matter of incrementally testing in combination various additional measures that you may not have planned on doing. For example, if a house is ahead on heating but behind on cooling, then efficiency measures that aid cooling should be considered first. However, it’s also possible to achieve compliance through improvements to the heating system, even if the cooling is still below the minimum. That’s the advantage to using the performance method, and it’s sometimes the only way that highly glazed designs can pass.

If one measure isn’t available for a project, we can try others instead. Of course if there are too few alternatives – say they can’t afford to replace all the windows or they don’t want to get a newer, more efficient water heater – well, something still has to give. Resorting to elaborate workarounds in an effort to save money can introduce other risks into the project.

Yes, we feel your pain, too, but you still have to replace those windows.

What additional measures should I be prepared to consider?

Based on our own experience of 15 years doing Title 24 compliance for low-rise residential buildings, here are the findings that seem to hold true across projects.

Insulation. For remodels, do not leave any portion of wall un-insulated! This may not mean the entire house, unless we have to model it that way. Insulating to the maximum of what will fit inside the walls should be a given. This can include portions of the interior walls, too. (Radiant barriers are good in hot climate zones, but they don’t make much difference in San Francisco.)

HVAC. Upgrading heating, cooling, or water heating systems. This can be upsetting if the furnace is recent, but not quite recent enough. If your furnace has an AFUE of .90, but the project won’t pass unless that AFUE is .92, we have to deal with the situation as it is and find some way to address it.

For any remodel or addition project in California, additional measures may be required for Title 24 energy compliance. Clockwise from upper left: replacing inefficient windows, upgrading to more efficient heating/cooling/water heating systems, adding extra insulation, earning credits through HERS tests such as this blower door test, and finally, solar shading for homes that have problems with summer solar heat gain.

Windows. Replacing all or most of the existing windows. Obviously this can get expensive, and we try to avoid this. On one project we had to specify every HERS test there was, because they wanted to keep 5 existing windows that were metal-framed with clear glass. This project also had existing window that were wood framed with clear glass, but it was the metal ones that hurt the project the most. Poor window performance is the Achilles heel of compliance.

HERS verifications. We used to discourage the use of these third-party tests because it’s cumbersome to have to coordinate for yet another inspection during construction. And, there’s no guarantee that the test will pass on the first try, although there are ways to prepare for them to help things go smoothly. Now we’ve had to resort to them for about half our Title 24 projects.

Design changes. Our whole raison d’etre is to help architects comply with Title 24 without having to alter the design in a visible way. No shrinking of windows, no adding of south wall overhangs if the original design didn’t call for them. We’ll recommend product substitutions, but we’ve never had to tell someone that they couldn’t have their all-glass panoramic view. Still, I’m sure someday we’ll get a project where adding an overhang or side shading wall makes that 0.01% bit of difference between passing and failing.

Windows can leak heat in cold weather, but they also can admit too much solar heat gain on hot, sunny days, as shown in this illustration. The window on the left would be associated with higher cooling loads.

How accurate is the Title 24 software model? Just because a measure doesn’t help in the model, does that mean it’s really worthless?

Absolutely not! The Title 24 modeling software calculations are actually pretty thorough, although there are some intentional omissions that can, at times, make the building’s real-world performance quite different from what the model would predict. A home that in reality is covered by shade trees and a nearby mountain may show unrealistically high cooling loads in Title 24, because shade trees, adjacent buildings, and landforms are specifically not allowed as factors for compliance. I’m not going to get into the reasoning, but that’s how it is. Title 24 errs on the side of conservatism, so a house that does well in Title 24 should also do well in reality, even if the reverse is not always true.

What it’s good for is comparing the relative impact of one change over another. You can test the sensitivities of using triple glazed vs double glazed windows on just the west or south walls, for example, to see where you can get the most bang for the buck.

I don’t think the Title 24 software models are quite accurate enough to create energy budgets for things like Net Zero Energy homes, or to model temperature flows for passive solar designs. For one thing, appliances like TVs and computers aren’t considered at all, nor are differences in occupant behavior. It could give a rough cut analysis of major opportunities for optimizing the design, but then you’d have to move to something else.

Imagine a home built in the Plains region of the United States that stays warm in the winter without central heating, and cool in the summer without massive air-conditioning. It’s airtight but with an endless supply of fresh air constantly circulating through a filtered, pressure-balanced ventilation system. Every surface is comfortable to the touch, neither too warm nor too cold. Street noise is barely audible through the gasket-sealed, triple-paned windows. 

It sounds futuristic, but so-called Passive Houses have been around for at least 15 years, and it’s yet another strategy for saving energy. Unlike a Net Zero Energy home that might rely on “active” power generation, albeit from renewable sources, a Passive House is just that – passively absorbing heat from its surroundings to release it slowly as it is needed. (In hot climates, Passive Houses are designed to recover and store cooler temperatures.)

Passive House History

The idea of a “passive house” originated in Germany as a result of conversations between two university professors. A Passive House (Passivhaus in German) is a building that requires very little energy for heating and cooling, instead relying on passive energy sources and thermal isolation from its surroundings to achieve temperature stabilization. The notion began around 1988 and is now widely accepted in Germany and Europe. It’s now a standard, with specific and measurable performance requirements that can be field-tested and verified.

Buildings that meet the Passive House standard include public structures such as schools and supermarkets, as well as private residences. In the United States, the Passive House Institute US in Urbana, Illinois is a consulting and research firm working on adaptation and implementation of the Passive House standard within the United States.

This existing home in Ireland has been retrofitted to meet the Passive House standard, and yet it still looks just like every other house on the block. Designer: MOSART Architecture

Here in the Bay Area, Quantum Builders has become a recognized expert in the creation of Passive Houses tailored to our local climate. (Note that there is another builder of that same name in Texas, unrelated). An upcoming project in Tiburon is due to start construction this year, and was designed by award-winning architect Olle Lundberg of Lundberg Design. Bronwyn Barry of Quantum Builders spent considerable time explaining to me how it all works and showing me some of the wall assemblies that Quantum uses in their Passive House projects.

Wall details from above house showing "before" and "after" the Passive House retrofit, from the MOSART web site.

I also spoke with Jonah Stanford of NeedBased Inc., an architect based in New Mexico who’s a Certified Passive House Consultant with a successful track record of completed projects that employ advanced solar design principles in an artful and responsible manner. 

Passive House in a Nutshell

Passive Houses rely on an airtight envelope, lots of insulation, thermal mass, heat-recovery ventilation systems, and a thoroughgoing approach to slowing heat transfer through the walls that leaves no stone unturned. Wall assemblies tend to be thicker – in some retrofits, it’s like wrapping an additional blanket around the existing house – but the most unusual thing about the walls apart from air tightness is the extreme attention paid to eliminating thermal bridging. “A typical home can lose 25% of its heat from thermal bridging,” said Bronwyn.

Thermal bridging can be responsible for 30% of heat loss from a home. Wood frame studs have a lower insulating value than the batt insulation between them, and if the studs are directly in contact with the inside and outside of the wall, they can act to conduct heat out on cold days, resulting in unwanted heat loss.

In a way, it’s not unlike NASA sending up a manned spacecraft and having to account for every last gram of weight, to ensure that there’s enough fuel to get it to its destination. The interior has to be kept warm enough to keep out the cold, which is a chill far more extreme than anything you’d find on the Earth itself. And of course, manned spacecraft have to be airtight, because any air leakage at all would be disastrous.

The idea with a Passive House is to stabilize temperatures by making the thermal mass of the house work for you like a giant hearthstone. You don’t need a conventional furnace at all – even in Northern Europe! Once the house is at the desired temperature, it takes very little energy to keep it there. “Improving a home’s airtightness can result in 25% energy improvement,” said Bronwyn.

Passive Houses have been built in every climate zone. Desert climates of course are more concerned with keeping cool by managing solar heat gain, whereas cold-winter areas are more concerned with staying warm. Tailoring the design for the specific climate and site conditions is of paramount importance.

Clockwise from upper left: Crossway House by Hawkes Architecture in the U.K.; Breezeway House in Salt Lake City, Utah by Brach Design Architecture, the first certified Passive House in the U.S.; zero-emissions research station in Antarctica.

(Note: I’m not sure that they are all “Passive House certified” but they all use the basic Passive House principles. Breezway definitely is certified, and Crossway is “zero carbon” home that has also been accredited by the Passivehaus Institute in Germany. Bronwyn mentioned the Arctic research station as a Passive House, so maybe it’s actually certified as well.)

The Passive House standard doesn’t specifically require the use of non-toxic materials, although the wall assemblies that I saw used materials that were carefully chosen partly for low toxicity – cellulose and rock wool insulation, wood and low-toxicity oriented strand board. Off-gassing isn’t as much of a problem as I had originally thought: the ventilation system has a low but constant rate of air exchange that doesn’t allow stale air to accumulate anywhere in the home. Passive Houses are credited with having excellent indoor air quality; that’s one of their selling points.

Humidity also has to be managed, as with other tight-envelope buildings. Placement of vapor barriers is dependent on climate, similar to other types of construction. The wall assemblies at Quantum Builders showed extensive attention to waterproofing as well as the placement of air and vapor barriers.

Rafter detail showing vapor barrier at interior (blue,) air-barrier at existing siding (red) and bulk moisture barrier at roof sheathing (red.) Arrows show air movement within the roof assembly, allowing air to escape from vents in the roof for passive cooling. Taken from a study for a Passive House retrofit by Quantum Builders.

Like other standards, a Passive House building performance analysis includes the creation of an energy budget. Energy budgets are a key component of many other energy-saving approaches and standards such as passive solar design, GreenPoint Rating, HERS home energy audits, Net Zero Energy homes, or California’s Title 24 energy standard. The Passive House energy budget is thorough and detailed, including occupants, appliances and lighting. Both power consumption and heat generation are considered. 

How do Passive Houses differ from, say, Passive Solar or Net Zero Energy homes?

Passive House is more than a set of principles – and it’s more than a checklist. Passive House is a formalized approach with an associated standard, modeling software, energy budget, and certification/testing process. To be fully certified, each Passive House is verified against actual building performance after the building is completed, as follows:

1. Heating and cooling demand is less than 4.75 kBTU per square foot per year. (A regular house might use 15 times that amount.)
2. An air-tightness rating of less than 0.6 air changes per hour, measured at 50 Pascals. 
3. Energy demand for all uses (called “specific primary energy demand”) including hot water, heating, cooling, auxiliary, and household electricity is less than 38 kBTU per square foot, per year.

The Passive House performance standard.

By comparison, passive solar design isn’t really a “standard” that can be pass or fail. The passive-solar approach looks at building orientation and other principles of solar design, but there’s no specific energy modeling software associated with it (although many software programs can be used to assess most of the solar gains, etc).

Net Zero Energy homes don’t really have a standard or certification other than daily use. They do have a performance goal: use less energy than you produce within a single year, with an annual reckoning every December between you and the utility company. If you’re grid-tied and your energy bill for the year is zero, then yes, you produced more than you consumed, so the house is Net Zero – at least for that year. But there’s plenty of synergy among these approaches. “Passive House gets you super-close to Net Zero Energy”, says Bronwyn. “If you meet the Passive House standard, then Net Zero is easy.” A Passive House requires less energy to begin with, so you’d be able to reduce the size of your renewable-energy systems accordingly.

Title 24 does provide good baseline performance measures, as Bronwyn explained. “The R value needed to meet the Passive House standard varies by climate and is determined per project using the Passive House Planning software. In Minnesota, you might need R30 to R40 walls and R50 roof. Here in California, a Passive House should have around R21 walls, R11 insulated slab, R28 roof, and really great windows.” By comparison, Title 24 mandatory minimums are R30 roof, R13 walls, R19 floor, and Low-E windows. 

The differences lie in the root of each strategy. 

• Passive House is about temperature stabilization as the main focus for reducing the need for actively generated power. 
• Net Zero Energy is about achieving a “net zero” balance between onsite power generation and power consumption, with a strategy that includes active power generation through solar, wind, or other renewable energy sources.
• The GreenPoint Rating system focus is on long-range resource conservation, energy efficiency, community design, and environmental health. So does LEED.
• They all differ from Title 24 in that you can factor in your shade trees for credit, or include these features as part of the energy model.

Tell me about energy budgets in Passive Houses.

Part of the Passive House standard involves setting a specific overall energy budget for the home based on “treated floor area”, or conditioned square footage up to the interior wall area. The Passive House energy budget is imposed purely based on size regardless of activity, and includes all appliances, not just heating and cooling. It’s up to the owners to decide how to use that budget. It’s challenging to meet the standard, but definitely possible. Typically, you have to be very careful when selecting appliances. The Energy Star rating only sets a minimum efficiency; within that, appliances can vary widely in how much power they actually use.

The Passive House software tool, called the Passive House Planning Package, is an elaborate Excel spreadsheet that helps to create a detailed energy model of the home. Although use of this tool isn’t strictly required, it seems to cover every possible angle and takes all the Passive House principles into consideration.

What if you want to light a couple of candles over dinner? Will this throw the house off?

A good ventilation system can take that into account. What most owners do is they open a window! But yes, you do have to be aware of every heat-generating activity that you do. However, Passive Houses can accommodate a wide variety of activities and lifestyles. You don’t have to be afraid of exercising in a Passive House or of hosting large groups of people. In Germany there are entire kindergartens and office buildings that are Passive House certified, even an indoor pool!

What happens if you leave for a long weekend and forget to take out the trash?

The first question everyone asks when they hear about a hermetically sealed, airtight house is “What happens if you fart indoors?” Even though the question itself is crass, the concerns about stale air are reasonable enough, given all we’ve heard about airless offices and flu-laden airliner jets.

“Passive House ventilation systems usually have a ‘flush’ feature nowadays,” said Bronwyn. “If you need to clear the air, you can activate this cycle and then the system resumes normal operation.” As with the above question, you can also open the windows for 10 minutes, air the place out, then shut them again without seriously disturbing the temperature balance inside the home. 

Passive Houses have better air quality than so-called normal buildings. Bronwyn and I spent time discussing the chronic health issues so many urbanites face, from asthma to migraines. She quoted me longitudinal studies from a school in Germany that showed reduced absenteeism, improved occupant health, increased attention span, and reduced CO2 levels. “In a Passive House, the indoor air is constantly being filtered and circulated, while stale air is constantly being expelled.”

Can you use carpeting inside a Passive House? Are there certain conventions for indoor furnishings and materials that need to be re-examined?

Yes, you can, and any dust it generates will be less of a problem because airtight houses are less drafty. There are no stray air currents to kick up dust into the air. There is no reason why you couldn’t use all the same interior design techniques that you would in any other home.

What’s it really like inside a Passive House?

I asked this question of Jonah Stanford. “It’s like being on the moon,” he answered. “It’s amazing, really. The house acts totally different in some ways from what we’ve been conditioned to expect. If you stand near a window on a cold day, you won’t feel a thing. Normally you would feel a thermal draw from the window in cold weather.”

A cross section from a window designed using Passive House principles. It features argon gas-filled triple glazing, thermal breaks, insulation inside the frame, full gasket seals at three places inside the frame, and a waterproofing system on the outside to trap and guide rainwater out and downward.

The evenness and stability of the temperature inside a Passive House eliminates hot and cold zones that we may be used to. “I went to a 2 story office lobby that used Passive House principles and we measured the temperature at the floor, the wall, and the roof. It was all exactly 21.5 degrees Centigrade. Phenomenal.”

Do occupants feel separated from the outdoors?

Not at all. Passive Houses are quieter, but they actually have more fresh air. Occupants can open windows when it’s nice outside as much as they want, just as they would in a conventional house. The only differences is they don’t HAVE to.

Does the Passive House standard REQUIRE that you purchase special building materials all the way from Germany? Can’t you do it using local materials?

Yes you can. Quantum has chosen to work with German manufacturers because they’ve got more experience building to the Passive House standard. Importing assemblies from Germany to the Bay Area actually uses less embodied energy than, say, trucking them from Minnesota. Apparently to be really “carbon compliant” everything trucked by surface has to come from a distance of under 300 miles. 

It’s not the materials, it’s the details that have to be reworked. All thermal bridging must be eliminated, which requires special measures. In addition, airtightness, vapor protection, and waterproofing all need to be addressed.

Insulated roof ridge detail before and after, showing how R-values were improved from a mere 2.2 up to R-50. Taken from study for a Passive House retrofit in Larkspur, by Quantum Builders.

There are no books on typical detailing for Passive Houses – yet. Builders on the East Coast can often use details from German books on Passive Houses, but these details are optimized for a cooler climate and rely more on masonry than on wood frame construction which is most commonly used here in California.

Aren’t the floors cold? Is every surface supposed to be the same temperature?

There is slab insulation under the home to keep the floors from leaking heat out into the ground. A Passive House has a lot of thermal mass partly to keep every surface temperature constant. Thermal imaging via a software package called THERM is a useful supplementary tool. Bronwyn showed me two thermal images, similar to the example image shown below, comparing the effect of placing slab insulation either above or below the slab. 

Imaging example showing a thermal model of a floor to wall assembly, from the software package THERM. Image courtesy of Quantum Builders.

Although both floor surfaces were warm where the floor met the air, the warmth went deeper when the slab was exposed and could warm itself. With the slab underneath, it sucked cold up from the ground and stayed that way.

How NOT to design a foundation. This shows how thermal bridging can effectively drain all the heat out of your home.

What does the ventilation system need to do?

For a Passive House, you need a good mechanical heat-recovery ventilation system with balance between air intake and exhaust, delivering 0.6 air changes per hour. The house should have an even pressure balance between inside and outside air. Air filtration components may be selected based on the location and occupant needs, but are always present. Special attention is paid to the location of openings for air intake, which may vary by climate as well as site. For example, intake in very cold climates may require some form of pre-heating via earth tubes.

“HEPA filters aren’t always necessary,” said Bronwyn. “Passive Houses have lower airborne particulates already, because there are no indoor convection currents (drafts) to stir up dust. The fact is, so-called ‘normal’ indoor air quality is poor to begin with.” 

What additional costs are associated with building a Passive House as opposed to a “regular” one?

The Wikipedia article on Passive Houses contains the statement that overall, Passive Houses cost on average 14% more to build and are more expensive in Northern latitudes above 60 degrees. Other sites claim 10% overall or 7% in Germany. I didn’t get a figure from Quantum, although it’s clear that the additional insulation and thicker walls do add somewhat to the cost. 

“It’s really important to have a fully committed client,” said Bronwyn. “Otherwise they may not want to go all the way.” I observed that most people don’t view their houses as legacy homes to be handed down to their children. It seems that most people stay in their homes about 5 years or so and then move on. They’re not as willing to invest in improvements that you can’t see.

Do Passive Houses have a thermostat?

Yes. Typically this would be set to 68 degrees, and is adjustable to suit occupant preference.

Can you have multiple heating zones for sedentary vs vigorous activity?

If you want to have a small office that’s nice and warm, while the rest of the house is at a cooler temperature, you can use a small portable space heater. This can be accounted for in the home’s energy budget during the early planning stages.

How well do Passive Houses do in extreme climates?

There are Passive Houses built in all seven climate zones in the US. There’s even one in Antarctica, a research station. A desert Passive House will be geared more towards cooling, but the actual wall assembly is similar to what you would use in Minnesota, in both cases well-insulated and protected against thermal bridging, because in either case you want to minimize thermal transfer through the walls.

This desert home by Kendle Design is not Passive House certified, but it uses the same principles of solar design that would also be employed to build to the Passive House standard: massive earth walls and solar shading. It might be challenging to make a glass wall this large using the airtight, triple-paned construction details shown on other Passive House windows, but who knows?

Within the U.S., the most challenging climates seem to be the cold regions around the Canadian border, and the extreme heat and humidity in places like Florida and the Gulf. Sometimes the use of geothermal or earth warming tubes buried in the soil can act as heat exchangers to pre-heat or pre-cool outside air before it goes through the ventilator.

Let’s talk about special building techniques for Passive Houses.

The Passive House standard is performance-related rather than material-specific. Quantum Builder’s South African case study is 100% predesigned and prefabricated from custom-produced wall and roof assemblies. In the Ukraine, according to Jonah Stanford, there are Passive Houses built with monolithic wood walls, although I wasn’t able to find any immediate specifics online. Regardless of material, airtightness, moisture management, and the elimination of thermal bridging are important considerations when designing specific wall assemblies. 

What’s inside this wall assembly here in your office?

From inside to outside: 

1. Drywall
2. Furred-out mechanical chase
3. Oriented strand board layer for air-barrier & structural sheathing
4. Cellulose between the structural framing
5. Insulated fiberboard impregnated with wax
6. Rain-screen furring 
7. Exterior siding

One of the wall assemblies on display at Quantum Builders' offices.

What about the windows in a Passive House?

The one component that isn’t easily obtainable here are the windows. Windows that meet the Passive House standard are hard to come by. They must be airtight, triple glazed, with insulated frames, with a very low U value – .14 or even as low as .11. All moving parts must be precisely fitted, like airlocks in a spaceship.

“R values of typical window are poor. A typical vinyl window is around R2, and the best Marvin windows are around R3.2. The R value of a Passive House window needs to be more around R7 to R9,” said Bronwyn. Considering that the minimum wall insulation in CA is now R13, the windows present the primary avenue of heat loss in a home, and it pays to make them as thermally efficient as possible. Installing the windows presents an opportunity for further insulation. In some cases the window frame can actually be layered behind additional insulation extending from the walls of the house.

The thermal performance of a window is influenced by the performance of the frame, the glass, and the spacer. In addition, the installation method can affect the performance of the entire wall. Each of these components within a window should be as thermally efficient as possible.

Bronwyn had special words about vinyl windows. Although they’re encouraged in Title 24 as being efficient, they have a reputation for off-gassing. And they’re still not airtight enough. The windows used by Quantum are made from wood, sometimes with aluminum or fiberglass cladding. The fiberglass clad windows are enhanced with a special insulating foam: Neopor- a super-insulating carbon impregnated type of EPS, on the outside of the window.  Any gas that escapes can’t penetrate the air barrier to get inside the house.

If you import special materials and such, do these products meet local building codes and standards?

I was especially interested to know if the imported windows were NFRC rated. Bronwyn informed me that their window manufacturers were in the process of getting their products rated, which can take up to a year. 

Why would you choose to go with the imports rather than building it locally, then?

Passive House materials must be built to the most exacting standards possible. Air-tightness must be controlled at every joining, every assembly, every switch box. Rather than try to manually assemble everything onsite, it can be both faster and more quality-enhancing to produce components such as wall systems in a factory that is already set up to achieve these standards. Having vendors and suppliers you can really rely upon is vitally important. Right now, most of these factories are in Germany because the Passive House standard was originated there, by building scientists, with strong support from the German government.

Quantum Builders already had strong ties with Germany, and has chosen to work with factories that achieve precision and who are committed to using high-quality, non-toxic products. These producers offer custom details as well as a wide range of standard products to satisfy design-oriented architects.

Jonah Stanford confirms that Passive House standard does not mandate a particular type of material, only a specified performance threshold. “The German assemblies that Quantum uses are actually quite reasonable in terms of cost. We’ve also price-compared both the German imported assemblies versus site-built or prefab assemblies made locally, and it came out about 20% less than importing – basically the cost of shipping.” 

When building manually, you have to pay a lot of attention to thoroughly sealing all electrical and plumbing penetrations, to keep the vapor-lock tightness. “You have to be obsessed with it, and even so, the seals might not last as long as the building,” says Stanford.

Stanford is working on his own assembly, a double stud framed wall. What distinguishes this wall from a “normal” wall is the layering. “The interior wall is load-bearing. Then, I use oriented strand board – NOT particleboard, followed by another layer of studs that are not vertically bearing.” This idea was, he says, inspired by the Ukranian wood frame Passive Houses, which are literally built from the inside out. 

There can be conflicts with local codes or incentives. In NM the incentives are generous, but require adherence to ASHRAE Standard 62 which requires outside venting for appliances like dryers. In a Passive House, however, the heat from that dryer should really be kept inside the house, at least in the wintertime.

What special skills are needed to design systems for, and actually build, a Passive House? 

Bronwyn had a couple of thoughts on this. The first was to have an integrated team from the start. “Architect, owner, builder, energy analyst, structural engineer, mechanical – they all have to review the early drawings together,” she emphasized. The second was to produce good construction drawings and details. “If the details are clear, any builder should be able to build to them – as long as they understand the why.”

Can an existing home be remodeled to meet the Passive House standard?

Yes, although some details such as under-floor insulation, strongly encouraged in Passive House construction, can be difficult to retrofit in existing slabs. Bronwyn showed me some details for Quantum’s remodel project in Larkspur. 

Although the added thickness does increase the home’s footprint very slightly, this in and of itself is not a problem unless the home is on an urban lot right up to the property line. In that case, the retrofit might have to concede a little space on the interior.

For the roof, you might have to actually raise the roof in some cases, in order to create additional room to fit the necessary amount of insulation. In jurisdictions where they might be picky about adding 6 inches to the building height, you might have to build down or lower an interior ceiling.

Isn’t rigid foam toxic, though?

During the roof discussion, Bronwyn and I got into a side discussion of different insulation types and R values, which is a measure of the resistance to heat transfer (higher is better). Typical batt insulation has an R value of around 3.7 per inch, meaning you can fit up to around R13 into a typical 2×4 framed wall. However, some types of rigid foam insulation can do better. Polyisocyanurate, for example, has been claimed as being R8 or even R11 per inch. I’d been wondering about the toxicity of this – “polyisocyanurate” just SOUNDS toxic!

Bronwyn pointed out that in the case of the roof assembly, the foam is on the outside of the air barrier, and the polyiso isn’t the worst thing out there. Formaldehyde from conventionally made engineered lumber products is a LOT worse, lasts a lot longer after installation, and it’s ubiquitous in buildings already.

What happens as part of the Passive House design and certification process?

The steps to Passive House certification are as follows:

1. During the schematic design phase, use the software to determine which wall assemblies (R-value) will meet the Passive House standard for the particular project based on climate. From there, you can proceed to create a detailed energy model of the project including surface areas, ventilation, windows, shading, even prevailing wind speed. It is essential to have input from your design and build team during this refinement. When design is complete, the drawings and the project modeling file are sent to the Passive House Institute US for pre-certification prior to construction. This takes around 4-6 weeks and costs around $800.
2. During construction, a third-party inspector comes out to verify that the house is actually built to the drawings.
3. After construction is completed, a third-party inspector conducts an official blower door test, to verify that the home is airtight. This test can be done by a HERS rater, as long as that person knows how to test specifically to the Passive House standard. This includes verifying a neutral air pressure balance inside and outside the home.
4. The final step in certification is to re-verify the home against the as-built drawings. This takes another 4-6 weeks and costs an additional $300 depending on complexity and size of the project.

As Bronwyn noted earlier, special attention should be paid to construction detail drawings. Construction Documents are one phase that sometimes gets short-changed, because clients mistakenly believe that it will “save them money” – and then those details get worked out in the field by the builder. With a Passive House, you can’t do this because those detail drawings will be required for verification during construction.

What do architects need to know in order to design a Passive House? Would they work with a special builder or consultant to do the modeling?

Jonah Stanford mentions that you have to design to the Passive House standard from the beginning of the project, which would seem obvious but it’s worth pointing out that if you start out designing a standard home (or standard remodel) and you’ve already gotten as far as construction drawings, and THEN you decide to meet the Passive House standard, you will have to re-do all the wall assemblies. Expensive. “You can’t change horses in the middle of a stream,” I said, to which Stanford responded, “No, it’s more like switching from horseback riding to driving a herd of pigs through the water.”

How did you choose Lundberg Design for a passive house project? 

There was a long and careful selection process, where we interviewed several architects.

This straw-bale house, also built by Quantum Builders, isn't a certified Passive House, but it uses passive solar design principles, and it's quite a nifty shape.

What’s the response from Planning to your project?

They’re fully behind it – as long as it still complies with the building code.