OK, I’m the first to admit that I know next to nothing about water heaters. Aren’t they those white cylinders that live in garages, as far as possible from the kitchen and the shower? Well… yes and no. In our Title 24 work, which is architect-designed custom single-family projects, the water heater is usually the last thing on anyone’s mind. However, on many of our analysis projects, the quickest, cheapest way to comply with California’s stringent energy-efficiency requirements has been to upgrade the water heater – and sometimes, to include a solar hot water credit.

This article explains how to assess water heater efficiency numbers, including the use of a handy lookup database at the California Energy Center’s web site.

California energy compliance calculation shows separate scoring for three main energy areas: heating, cooling, and water heating. A proposed design, here for a custom single-family home, can be behind on both heating and cooling and still make it up with a high-efficiency water heater.

Why’s water heating so important all of a sudden?

Well… if if a project is behind on heating AND cooling, and it’s already maxed out every other trade-off measure, it can sometimes be salvaged by running it with a more efficient water heater, specifically, a tankless. You’ll really feel the pinch if your project needs to exceed Title 24 by 15% or more. This is a basic requirement for almost all of the “beyond compliance” green standards: GreenPoint Rated, CALGreen optional tiers, LEED for Homes, and incentive programs such as the New Solar Homes Partnership. Local California jurisdictions are adopting various forms of these optional tiers, in some cases requiring very high GreenPoint Rated scores for larger homes.

“The equipment you see with values above about 90% are condensing equipment that have great efficiency values but need different installation practices and cost a bunch more,” warns Ken Nittler, creator of the Micropas Title 24 energy modeling software. “The most common equipment we see are small storage water heaters with energy factors of 0.60 or 0.62. On tankless, we see energy factors of 0.82 or so. On tankless condensing units, we see 0.94 energy factors.”

General Compliance Notes

Radiant Heating. Some basic questions that affect water heaters in Title 24 have to do with the heating system: specifically, whether radiant heat is under consideration. When you run a Title 24 calc with radiant heat as the specified heating type, the water heater drives both the Heating and the Water Heating portions of the score. The Heat score is sensitive to the water heater’s Recovery Efficiency, while Water Heating is associated with the water heater’s Energy Factor.

Solar Hot Water. There’s a very substantial credit for solar hot water in Title 24. You’ll need to know the “insolation fraction” which is the portion of total hot water that you expect to receive from solar thermal. A realistic number may be 25-50%, but that depends on how much sunshine the house will actually receive based on weather, site configuration, surrounding buildings and landforms, house footprint and available space for solar thermal panels, shade trees, and the like. Plan on having a supplemental unit such as an indirect storage tank or an additional water heater, since you’ll need hot water at night as well as during the day.

Radiant + Solar Hot Water Combined. If you’re going for radiant and/or solar hot water, you’ll need a mechanical consultant with strong knowledge of the differences among different manufacturers and unit types. For one thing, radiant heating water temperatures may be different from what you’d need for domestic hot water, so if you’re running them off the same unit or the same tank, specialized installation or components may be needed.

No Electric Water Heaters, Please! Fuel source, such as whether the water heater is gas-fired or electric, has a big impact on Title 24 compliance. Even for all-solar homes. There’s a huge penalty for electric resistance – that’s all you need to know for today’s discussion.

What’s the Highest Efficiency Realistically? The technology inside the water heater, such as whether it’s a two-stage condensing system or a hybrid, can have an indirect impact on Title 24 compliance. Sometimes if something’s not passing I’ll just test some of these numbers to see what happens, but eventually the numbers have to be realistic. This is where I asked around a bit to make sure that a water heater with a .95 efficiency was a real animal. It is – for a tankless. Condensing boilers also can have efficiencies as high as .95. There may also be condensing storage water heaters available, probably at a high premium.

Tankless or instant water heaters typically offer higher efficiencies, and thus are an advantage for demonstrating California energy compliance. Their real-world efficiency depends on other factors such as their proximity to the point of use.

Installation Issues. Do yourself a favor and check with your builder and subs before specifying some of the high-efficiency condensing water heaters. “The equipment you see with values above about 90% are condensing equipment that have great efficiency values but need different installation practices and cost a bunch more,” notes Ken Nittler.

Types of Water Heaters

Water Heater vs. Boiler. What’s the difference between a water heater and a boiler?

• Water heaters cost less and operate at a lower temperature. The “small” version, more typically used for small to medium sized residential dwellings, has an input under 75,000 Btu/hour. Large water heaters have an input that is over 75,000 Btu/hour.

• Boilers make scalding hot water, and more of it, typically around 200 degrees Fahrenheit. That’s why it’s called a “boiler”. A boiler is primarily intended for space heating (radiators), rather than making hot water for daily use. However, boilers are less adaptable to making hot water at lower temperatures at the 120 degrees for showers or 120-135 degrees for radiant flooring.

• They use different efficiency measures, and this last point is what’s crucial for Title 24 compliance.

Indirect Storage Tank. This is a separate, insulated storage tank with a heating element that can be used to collect and store hot water from an intermittent source such as solar thermal. It doesn’t actually heat the water up, it just keeps it hot after it’s already warmed by some other means.

Energy Compliance Calculations – Inputs Needed

Title 24 Defaults. About 90% of the time, we run our Title 24 projects using the software program’s built-in default, which is a small storage water heater with an energy factor of .60. This is a safely conservative assumption, since you can only go upwards from here. Within the Title 24 software, it’s the efficiency that seems to matter, rather than the number of units installed. In reality, however, larger homes are likely to have a boiler, or perhaps several different units at different locations.

Example of one of the pre-created sample inputs for the Micropas Title 24 compliance software. The values used here are specific to the water heater product specified, and they can influence whether or not a project meets compliance standards or not.

Efficiency Measures. Although the array of water heating technologies seem to be almost endless, the only thing that matters for energy compliance are these efficiency ratings, and they’re different depending on whether it’s a water heater or a boiler, whether it’s hooked up to a radiant heating system, and for water heaters the Btu input. There’s some confusion of terms here; I’m sticking to the terms as they are used in the Micropas software inputs.

Energy Factor. Used for “small” water heaters under 75,000 Btu/hour. The energy factor (EF) indicates a water heater’s overall energy efficiency based on the amount of hot water produced per unit of fuel consumed over a typical day. It’s a sort of umbrella measure that includes the recovery efficiency and standby loss measures described below, and is expressed as a decimal fraction between 0 and 1. An EF of .60 is average, while one of .80 will yield noticeable improvement in a project’s Title 24 compliance score.

Recovery Efficiency (sometimes called Thermal Efficiency, or AFUE, although they’re not exactly the same thing). Recovery efficiency is for “large” water heaters and boilers that are 75,000 Btu/hour or above. This is a measure of how effectively the unit turns fuel into heat. It is measured as a fraction between 0 and 1, higher being better. This seems to affect compliance score when radiant or hydronic heat is the main heating system.

Miles Hancock says, “Thermal efficiency is a useless number, measuring the unit’s efficiency at boiling water… what’s key is keeping that water hot, which is the standby loss. Standby loss is what kills the energy compliance.”

Standby Loss. Used only for “large” water heaters with a storage tank, this is the percentage of heat loss per hour from the stored water compared to the heat content of the water. In other words, once the water’s hot, how long does it STAY hot? This is measured as a fraction as well, in this case lower being better. The software built-in for the sample large water heater shows a standby loss of 0.03. Miles

Internal and External Insulation R-Value. Used for indirect storage tanks only. I haven’t tested the effect that this would have on residential compliance, because indirect storage tanks aren’t as common a configuration for the custom home projects that we analyze.

One thing that doesn't affect energy compliance is the style of the faucet - only what's behind it.

Other Inputs. There are additional inputs for heating element type (gas, electric, heat pump), rated input for gas heaters in Btu/hour, storage tank volume in gallons, distribution type, and for some types of water heaters, pilot light size in Btu/hour. For almost all our projects, the fuel type is always gas, since electric water heaters are discouraged.

The distribution type has to do with the piping configuration, and that’s mainly for larger residential projects. Example values are “standard” (the default), “Point of use”, or various recirculating on-demand varieties. I’ve occasionally run projects with these different distribution types to see what difference it made, and for a typical 4,000 SF single-family residential house, it made almost no difference in the compliance score. Sometimes it can make a big difference in the real world, though, so if you or your client are trying to maximize actual energy efficiency, as opposed to just complying with Title 24, try reading up on it in Ann Edminster’s book “Energy Free”.

Heater/Boiler Systems in the Title 24 Software Model. This is based on Micropas, which is one of two programs you can use for California energy compliance. I haven’t used Energy Pro as much, and it’s organized a bit differently. Here are a few basic types of heater/boiler systems that are set up as default or example entries in Micropas (and why you would pick one or the other):

• Small Storage. 40,000 Btu, 50 gallons, 0.60 EF. Use for legacy systems or if you don’t know what else to specify, and you want to assume the lowest allowable efficiency for the time being.
• Large Storage. 100,000 Btu, 100 gallons, 0.77 RE, Standby loss 0.03. Realistically this would be used for a larger home. However, I have noticed that specifying a large storage as opposed to small one lowers the compliance rating, probably because of the higher input rating.
• Tankless (instant). 195,000 Btu, EF .80, RE .76. This is the equivalent to a small storage water heater, and would be used in comparable applications such as a single family home as a more energy-efficient alternative. Compliance advantage is that it’ll boost the water heating portion of the score by as much as 30%, and it’s often a good choice in the real world as well. Real-world advantages: higher efficiency, theoretically endless hot water supply, smaller footprint. Real-world disadvantages: must be located close to point of delivery in order to realize energy savings.
• Boiler. 250,000 Btu, RE .80.
• Instantaneous boiler. 250,000 Btu, RE .80. Same as a boiler, but without a storage tank.
• Electric Storage. This is an electric resistance water heater. You will never, ever, want to use this type when using the performance method of compliance. Occasionally, if you’re trying to grandfather in some unpermitted basement addition, guest cottage, or in-law unit, and the space qualifies for prescriptive (not too much glazing!) you might be able to get away with stating “existing systems to remain” and bypass the issue. But that’s about it.
• Electric Heat Pump. I’ve never had to model this type of water heater, so I can’t speak to it. I don’t think the penalty is as steep for this type as for the electric storage.

Hot Water for Additions. If we run an addition as “Addition Alone”, water heating is not calculated. However, if the addition won’t pass by itself and we have to model the whole house, then the water heater becomes a potential source of energy trade-off. It’s even more important for additions and partial remodels, because other interventions such as upping all the wall insulation may not be available with projects of limited scope.

Pools and Spas. These are not included in the energy report calculations. There are separate energy standards that apply to them. For now, they are outside the scope of this article.

A Nifty Search Lookup for Current Models

Miles Hancock, one of our Green Compliance Plus Affiliates, walked me through the Appliance Efficiency search database on the California Energy Center’s web site. This database contains listings for all appliances certified to the California Energy Commission as meeting currently applicable efficiency standards – so it won’t be of much use for legacy systems (for remodels or additions). Some of the terms they use for efficiency are different from what’s described in the preceding article, but I’ve tried to list their equivalents above, where possible.

The California Energy Center's Appliance Efficiency search database lets you find the rated efficiencies of all models that meet current energy standards.

Many architects have yet to realize how much a window’s energy performance can impact their projects, especially under the new Title 24 energy code. Ordinary glass is great at letting in daylight but it’s a terrible insulator. It also does little to block the sun’s heat in the summertime. Windows lose heat through the glass, and they can also leak air around the edges of the frame.

Here are a few analogies to understand the different ways that windows can lose both heating and cooling energy. If you wear a big holey sweater in the wind, it doesn’t keep you very warm. That’s air leakage. Now, imagine just wearing a single sheet of clear plastic on a winter day. It’s a better windbreaker than that holey sweater, but you’ll still feel pretty darn cold. That’s because a thin sheet of plastic, like a single sheet of glass, is a poor insulator. And remember what happens to your car parked in the summer sun? It gets 20 degrees hotter than the outside, or more – if you have black vinyl seats, you’ll scream when you sit on them in your summer shorts. That’s solar heat gain.

When it comes to efficient windows, it's the entire window unit that matters, especially for air leakage. To understand the importance of air flow on energy needs, think of a sweater as your own personal "building envelope". Wool is a great insulator, but not if it's a holey sweater worn outdoors on a windy day.

Windows Lose More Energy Than Solid Walls

The more windows a house has, the more energy that house will require for both heating and cooling. And if those windows are on the South or West side of the house in direct sun, they can turn the home into a summertime toaster oven.

Windows can leak energy in several ways:

• Air leakage through and around the frame
• Heat transfer directly through the glass
• Thermal bridging through the frame, especially with metal frames
• Radiant heat from direct sunlight

Which building will be easier to heat in winter and cool in the summer, the saltbox on the left with modestly sized window openings, or the all-glass modern office building on the right?

What Kind of Windows Are More Energy-Efficient?

Title 24 requires that windows meet minimum performance standards. Most legacy windows don’t meet this standard, and a lot of fancy metal-framed windows don’t meet it, either, due to metal’s heat conductivity. There are metal windows that meet the Title 24 standard, if you’re willing to pay for triple-glazing, thermally broken frames, and argon gas fill. For a large house that’s got acres of glass, this is very expensive and it’s really overkill, too, in mild California. If you don’t want to break the bank, you’ll have to make it up with additional energy measures elsewhere.

By blocking infrared radiation, low-emissivity glass works both to keep the Sun's heat out, and indoor heat in.

There are many ways to make windows more energy-efficient:

• Special “low-e” glass that blocks solar heat radiation without blocking visible light
• Double or even triple paned construction with air layers sandwiched between the layers of glass
• Filling that air gap with argon gas instead of regular air
• Airtight frame construction
• Use of framing materials such as wood that are less conductive of heat
• Thermally broken frames to  further limit heat loss through the frame

Metal is a good conductor of heat, which is why metal cookware works so well. But that conductivity is the last thing you want in the walls of your house. Thermal bridging is another term for this type of unintended heat loss. To prevent it, some metal window frames include thermal breaks as shown on the right.

Windows framed in stone, poured concrete, or similar material might have similar properties to a masonry wall – but they’re less common and I’ve never had to model any.

Window Placement Can Make a Difference

In a moderate northern latitude, the sun's path through the sky summer and winter traces an arc across the southern portion of the horizon. This affects the amount of sunlight that reaches windows on east, south, and west facing walls of a building.

It’s probably not news that windows on the South and West walls let in more solar heat, but let’s consider windows on each cardinal direction. (Southern hemisphere folks will have the sunniest side on the North, but let’s stick with California for the moment.)

• East facing windows receive morning sun, at a low angle. Because the house is presumed to be still cool from the night, the solar heat gain from the eastern sun can actually be helpful in warming the house in the morning.

• South facing windows receive noonday sun, at a higher angle. How high exactly depends on your latitude and the time of year. The right size overhang can block sun in the summer, but admit it in the winter. Still, large areas of South facing glazing can be a liability for cooling.

• West facing windows admit the setting sun at a lower angle, but it’s after the heat of the day when you don’t want more solar heat gain. Large areas of West facing glazing can be a cooling problem – and, shading overhangs won’t help.

• North facing windows will never experience direct sun in California. Overhangs don’t do much for shading, although they’ll still keep the rain off. However, heat loss through the glass can be more pronounced on North facing windows.

Clockwise from upper left: In the morning, the sun is lower on the eastern sky and shines into an east facing window at a low angle. By noon, the sun is higher overhead in the south (although still at an angle). The setting sun in the west again shines through any west facing window at a low angle. North facing windows will never see direct sunlight.

Overhangs and Window Shape

Overhangs help with shading on the South, but a few other design features are important too: overhead clearance and whether the window has a more horizontal or more vertical shape.

Left: When shading a tall skinny window, much of the window area is still exposed. Middle: This horizontal wall of glass is situated immediately beneath a long overhang to shade a greater proportion of the glazing area. Design by Wendell Burnette Architects. Bottom: In this recent design from Swatt|Miers Architects, the horizontal windows, deep overhangs, and reduced amount of South facing windows all helped with Title 24 energy compliance.

Measuring Window Performance

There are two, and only two measures that matter for Title 24 energy compliance: the U value and the Solar Heat Gain Coefficient (SHGC). It’s important to understand the difference between the two.

• The U value helps with heating AND cooling.
• The Solar Heat Gain Coefficient only helps with cooling.

It’s true that I often ask people whether their windows are double glazed, single glazed, and whether the frame is wood or metal. That’s just when I need to come up with generic numbers for the U/SHGC. When it comes to Title 24, these two numbers are really all that matter, and the window products have to be officially tested and rated by the National Fenestration Rating Council (NFRC). Title 24 now requires that the windows be tagged, and that this NFRC rating be etched directly onto the glass.

(There are other important window performance measures, such as visible light transmittance and also the glass’ ability to block ultraviolet rays, but those aren’t considered in Title 24 energy performance.)

U Value

U value measures rate of heat transfer through the window. Lower is better. Both the framing material and the type of glass have a big impact. A window with a U value of .40 is whole a lot better at keeping the heat in on a cold day than a window with a U value of .75. Title 24 expects a maximum U value of .40, although you can find windows with a U value of under .20. Just for comparison, an ordinary window with two panes of clear glass might have a U value of .65.

Solar Heat Gain

Solar Heat Gain Coefficient (SHGC) is about how hot the interior of the house will get on a sunny day when that window is hit by direct sunlight. The hotter it gets, the more A/C you’ll be using. Well, actually it measures the amount of solar heat coming through the window. Think infrared heat lamp. In California, lower is usually, but not always, better. Title 24 usually expects a maximum SHGC of .35.

In far Northern latitudes you might want a higher solar heat gain because you’ll want to capture more of the sun’s heat in a passive solar design – but you’d still want a low U value.

Title 24 Window Performance Standard

The Title 24 baseline standard of .40 U/.35 SHGC assumes that you’re using a wood or vinyl framed, double paned, airtight window unit with specially coated “low-emissivity” glass. It’s generally better at keeping heat in, and it also filters out some of the sun’s more heat-inducing rays. Because sunlight has a range of frequencies visible to the human eye, some frequencies of visible light transmit less heat than others. So we can now obtain spectrally selective glass that looks relatively clear, but filters out a lot of the hotter rays.

Here's why metal framed windows are a problem. Even the better products don't always meet Title 24 minimum standards.

Single, Double, Triple Glazing

We occasionally get questions about whether there’s such a thing as a high performing single glazed window, and the answer is NO. There may be some variation in the thickness of the glass panes, but that alone won’t help much, nor will having a fancier glass type help all that much either. It’s the layer of air between panes of glass that does most of the work, and if you take away this layer, you take away 90% of that window’s insulating ability.

Remember that holey sweater? Well, assuming that you’re indoors out of a draft, that sweater might do a better job of trapping a layer of air next to your skin which warms to your body temperature and helps you feel warmer in a cool room. As long as nothing strips that air away, you’ll feel warmer.

Adding layer of air helps a window's heat insulating ability. Even more so if that layer is a gas fill like argon rather than regular air. For extreme climates, triple glazing may be needed.

Getting NFRC Test Results from Window Manufacturers

What we see in our Title 24 work comes from other small design firms doing custom residential design – firms like us. The architects who come to us for Title 24 consulting care a lot more than average about aesthetics, about design integrity, and about pleasing individual client tastes.

Top: This French style home designed by Taylor Lombardo Architecture used wood frame, double glazed, low e windows to achieve a traditional look. Bottom: This Modern design from Swatt|Miers Architects specified Fleetwood aluminum framed windows for most of the glazing. The grouping in the center of the illustration is actually a custom-built window wall. Green Compliance Plus provided the Title 24 energy compliance reports for both these projects.

Some window manufacturers are really good about posting their numbers, others are not. If you’re a design-oriented architect and prefer certain styles, you might have to get used to looking at the numbers first, and the appearance second. We’d hate to have to tell you to abandon some of your favorites, but if we can’t find the numbers, and the window manufacturers can’t tell us, we have to assume the worst when doing our Title 24 analysis.

In terms of window manufacturers for our various Title 24 projects, the names we see the most are for Milgard, Loewen (wood or vinyl); Fleetwood, Bonelli, Milgard (metal or metal clad); and Royalite or Velux (skylights) – but there are many more quality makers out there.

Sometimes we don’t see products by name, we just tell the designer what numbers they have to meet or beat. For those who really want metal, Fleetwood has a wide range of styles, including sliding doors, casements, awnings, fixed – as well as energy saving levels.

Here's an example of NFRC ratings for one window manufacturer, Fleetwood. They're one of the few metal frame window products offering triple glazed, argon filled, thermally broken frames.

Ultra High Performing Windows

Most of our Title 24 clients aren’t extremists in this regard, although they all want to get the best window they can within their budgets. The most efficient windows available are typically used either in Passive House certified designs, or in climates with more extreme cold – and sometimes those areas require a different formula with a higher solar heat gain – especially passive solar designs in extreme northern or southern latitudes.

Sorpetaler, Pazen (sold in California through Quantum Builders) or local manufacturer Serious Windows in the South Bay, seem to be the best. And they’re not cheap. The Sorpetaler windows that I saw at Quantum’s offices are as hermetically sealed as an airlock on a spaceship. They’ve got triple glazing, low-e glass, frames with thermal breaks, super low air leakage, argon gas fill – the works. Some of them perform almost as well as a wall in terms of limiting heat loss.

I’ve also heard a few people say that such extremes are wasted in the Bay Area where it’s so temperate that you’re better off investing in other areas rather than windows. Be that as it may, the window’s rated performance does make a huge difference in Title 24 energy compliance – deserved or not.

High-efficiency windows can be executed in a variety of styles as well as custom-built units. Clockwise from left are a modern embedded frame style from Pazen, a double hung unit from Serious Windows, and two traditional examples from Sorpetaler. Pazen and Sorpetaler are German manufacturers, while Serious Windows is located in Mountain View, CA.

NFRC Rating

Well what’s to prevent window manufacturers from making outrageous claims about their products? Regulations and a lot of cumbersome and expensive testing, that’s what. To ensure that people don’t fudge their own test results, window manufacturers are required to send all their stuff to a lab accredited by the National Fenestration Rating Council for physical testing. At the lab, they take the window units and test them, over and over, to measure how much heat they lose, how much of the sun’s heat they let through, and how much air leakage occurs. This process takes up to a year and costs $30,000.

The NFRC rating must be posted on each window unit at the construction site. In addition, California energy code requires that this same rating be etched right onto the glass.

To be considered 100% kosher, these ratings are for the entire manufactured window unit, frame and all. It’s not just the glass. There is something called a “center of glass” measurement that can be used for site-fabricated units such as curtain walls, but officials that we’ve checked with at various local Building Departments have all indicated to us that center-of-glass performance results are not really acceptable for Title 24.

Custom Field Built Windows, Frameless Butt Glazing, and Energy Efficiency

This is a thorny problem because field-built windows don’t have NFRC ratings.

You can forget about single glazed butt joined corner windows, unless they’re small. We recently had a couple of very ambitious glass wall designs, and to our astonishment the one with 67% glass to floor area did OK – eventually – that was because it was all double glazed. Even so, we originally thought it’d need to use triple glazing. Our design client almost had a heart attack. Way too expensive. Eventually we did make it work with double, but they had to make up for it with a lot of HERS tests.

Then we got another design from the same architect that called for miles of single glazed frameless windows including a lot of corner glazing. All single glazed. I thought, “Oh no, we’ll finally have to break our commitment to preserving design intent and tell them we can’t make it work unless they make the windows smaller! But we’ve promised to never, ever do that! They’ll never call us again.” Even there, by counting every possible square inch of interior thermal mass, and pushing them to go to double glazing even for the butt joints, we were able to get it to pass – by 15%, which was a requirement for that particular jurisdiction.

Getting the look of a seamless corner window with double glazing is a challenge, but it's possible. Here's one window detail provided by Swatt|Miers Architects.

Glass Technology

We recently had a question from someone asking what difference the different types of glass such as SolarBan or Cardinal might make. The short version is: refer to the NFRC ratings rather than asking us to evaluate the glass, and bear in mind that some options may cause the glass to appear different. SolarBan 70, which is an option on a lot of Fleetwood window products, offers better performance overall than SolarBan 60 but we had one designer tell us that she didn’t like the look of the 70 – “too shiny”.

For the low-e glass itself, most of the enhanced energy performance is the various coatings on the glass. The good news though is that new products are always coming out with better and more precise performance.

Further Reading

If your thirst for window knowledge still remains unslaked, here’s a good dissertation on windows from the Whole Building Design Guide, a program of the National Institute of Building Sciences.

We all know that every home in California’s going to be Net Zero by 2030, right? Actually, it’s every NEW home built after 2030 – the old homes can go on being inefficient, until the next time someone needs a building permit. At that point, serious attention may need to be paid to bringing the home up to date. And, increased enforcement now occurs at many different points throughout the project, making it harder to do swaps during construction.

The truth is, architects can’t rely on the builder anymore to specify and install systems and materials as an afterthought, because that’s far too late in the process; to make the right decisions, designers will have to start thinking in terms of building science. And, they’ll have to start paying closer attention to builder execution as well, because in many cases the builders will cut corners if left to their own devices – and this can lead to problems, regarding both regulatory compliance and the owners’ daily operational costs.

California’s Title 24 energy code has been mandating ever-higher levels of energy efficiency in residential construction since 1974. The latest tightening occurred just last January, when new energy standards went into effect. Now for the first time architects and their clients are really feeing the pain that comes with compliance: we’ve been telling them to use better performing windows, higher-efficiency systems, more insulation, and sometimes even HERS tests. All these items have their own measurements, architects need to  master the use of these measures until they’re second nature.

Some of our Title 24 clients, who are other residential architects, have very straightforward needs. They just want to comply with the requirements, period. Their clients are developers or homeowners who are basically motivated by expediency, and who don’t have a great commitment to sustainability. And that’s OK, because they’re still meeting a stringent baseline.

Others, however, have a greater interest in green building for its own sake. Even here their interest are wide-ranging: energy-efficient buildings, renewable energy, resource conservation, reduced fossil fuel output, grid independence, non-toxic homes, habitat preservation, adoption of better living patterns and habits, improved physical health, and reducing waste. Some are seeking official certifications such as GreenPoint Rating, LEED, or even Passive House certification. (Net Zero Energy isn’t a “certification” although it is a sort of yardstick.)

The top house is a typical developer product, built to meet the minimum energy standard - whatever local standard is currently in force. The lower house is a LEED certified project, and would likely exceed any local energy code. However, both would be equally subject to Title 24 standards if built in the State of California.

And yet, many designers have a hard time with concepts such as “building envelope surface area” or “window U value” and I realized after a while that they’re simply unused to thinking in these terms. They weren’t graded on these things in school, and I don’t think the California architectural licensing exams have a section on energy – the closest they get to engineering is the dreaded Lateral Forces section that has to do with structural strength.

Myths About Green Energy Design

We’re still dealing with a very simplistic thinking. Here are some myths that I used to believe before I read the books.

• Passive solar design is a fabulous one-size-fits-all solution.
• Every home should have a radiant barrier in the roof.
• Straw bale homes are the answer.
• No, no! The Passive House standard is the only way to go.
• Everyone should switch to solar power today.
• No, no – it’s better to focus on building better, more efficient conventional heating and cooling systems.
• Radiant heat is the best way to go.
• No, no – all-electric Net Zero homes are the best!
• Green is all about having bamboo flooring and never flushing your toilets.
• Green is all or nothing. Don’t bother with that unheated yurt if you’re still eating meat.

Building Science is Measurable and Performance-Based

What’s wrong with these statements other than their obvious stupidity? None of them measures the actual performance of real homes, or attempts to take multiple factors and conditions into account. It’s like trying to cure every physical ailment by taking Vitamin C without identifying the cause of the problem. And trying to solve the right problems using the right means is what building science is about.

Concepts that come up most frequently in home energy discussions include:

• Conditioned space. This is the floor area (and volume) within the house that is subject to heating and cooling, also called “habitable space”. This is different from Gross Floor Area that’s usually shown on the permit submittal. Conditioned floor area excludes garages, attics, and unheated basements that aren’t lived in. It is very important to consider which areas will be conditioned and which not, and to provide a way to firmly close off conditioned space.

• Building envelope. Usually this means the exterior surfaces of the building, but for energy modeling purposes, this envelope may include some unconditioned space as well. However, the performance of this envelope including insulation and air infiltration, has a big influence on energy efficiency. An efficient envelope limits air leakage and has no gaps in insulation that could result in unwanted heat loss.

• Opaque surface. Any surface that is not a window, like a wall, roof, floor, or door, is an “opaque surface”.

• Openings. An opening is either a window or a door. If the opening isn’t covered but is fully open to the outside, the room behind it is a porch and isn’t considered as conditioned space.

• Glazing. Anything with glass, including windows, skylights, and sliding glass doors. The total area of glazing is a major influence on energy efficiency, as is the ratio of glazing to conditioned floor area. In Title 24′s “standard design” this ration can’t be greater than 20%. In other words, if you have a house with 2,000 SF of habitable space, the Title 24 baseline assumes no more than 400 SF of glazing – including skylights.

• Heating load. This is the amount of energy it takes to keep the house a warm toasty 72 degrees in the winter. It takes more energy to heat a home in a cooler climate than it would for the same exact home in a warmer climate. If that home is leaky and uninsulated, it will also incur a higher heating load, no matter where it’s located.

• Cooling load. The amount of energy it takes to keep the house cool in the summer. Like heating, it’s a function of house efficiency and also its geographic/climate zone location.

• Water heating. The amount of energy it takes to supply hot water to the home, based mainly on the efficiency of the water heater itself.

Building Science Is No Longer Optional

It’s funny that I’m writing this article since I have no training in building science other than using the Title 24 energy modeling software. Then again, if I can learn it, anyone can, so let’s try to make this a fun excursion. Title 24 has been described as “killing a mosquito with a mallet” so I’m not saying it’s perfect. But, the California Energy Center has spent a lot of time and effort trying to apply valid principles across a broad spectrum of conditions, with input from numerous engineering experts and organizations – so it’s not “made-up”.

But, the CEC also knew that if it made everyone calculate their home’s energy use by hand, nothing would ever get done. So, they developed a few software programs to speed the analysis, and you don’t need to be a rocket scientist to use these programs, either. (You just need to be patient, methodical, and have a high tolerance for repetitive, detail-oriented tasks.) Here at Green Compliance Plus, I’m the one that does most of the modeling, and I spend a lot of time trying to get our clients (other architects) to understand how to think about building performance, and what influences it.

This depth of understanding used to be optional, but now even basic designs are not passing Title 24 without additional measures. Designers have to know what these measures are in order to determine whether or not it will work on their project. And, designers have to start anticipating energy needs upfront far more than before, to avoid unpleasant last-minute surprises. Why? Because if you don’t pass Title 24, you can’t get a building permit. It’s as simple as that.

Sometimes designers ask us over and over why they can’t just do X, or they say, “But I can’t do any of the things you suggest!” It is sometimes hard to explain that no matter how I run it, I can’t get rid of some necessary energy feature – not without adding six other measures that by themselves aren’t as effective. It’s because the Title 24 standard itself is a constant and unchangeable constraint. You have to meet or beat this standard, and that’s all there is to it. No shoes, no shirt – no service.

Models as Essential Tools

Images like these are both generated by computer models showing airflow (left) and air turbulence caused by a jet engine (right), to visualize forces that normally can't be seen directly with our eyes.

A “model” is really “a way of looking at the world” or a specific aspect of the world. Models and theories are used to predict things, and they’re verified by tests in a laboratory or elsewhere. A model attempts to take into account all the possible conditions that would influence a specific outcome. Software models make it possible to make predictions based on a greater number of factors. Then you can test each factor one at a time. There are software models for all sorts of things, not just physical phenomena.

Models can be physical, or written sets of instructions, or software. Software models in general have three parts:

• Inputs
• Instructions to the program itself on what to do with the inputs
• Results

It’s a “black box” in a way. The only thing you can change are the inputs. However, by testing different inputs carefully and doing multiple “runs” you can figure out what effect each input has on the results.

A model as a "black box" is illustrated by the famous thought experiment called "Schrodinger's cat", where an imaginary cat is placed inside a sealed box with a certain probability of demise every hour. The experimenter wouldn't "know" if the cat were still alive until the box was opened.

The Title 24 Software Models

In a nutshell, the Title 24 software model takes your information about a proposed design, calculates its projected energy use for an entire calendar year, and creates an “energy budget” showing how much energy the home will need to maintain comfortable heating and cooling levels. It then compares this proposed budget to a “standard design” that has certain basic characteristics (such as small windows and thick walls) but in other ways is the exact equivalent of the proposed design. This allows the program to compare apples to apples and is a bit fairer than expecting every new home to be under 1,200 SF and shaped like a cube. There’s no upper limit to the home’s size and/or energy budget, either.

The Title 24 software model compares your proposed design against a "standard design" that is fairly compact, with modest window areas. The proposed design can make up shortfalls in these areas by going beyond the minimum in other measures, such as adding extra insulation.

Because Title 24 is a regulatory, mandatory standard rather than an option, it’s heavily encumbered by a lot of bureaucratic rules. Any software program used to generate Title 24 energy compliance reports has to be approved by the CEC. The only use for the software is to get a building permit within the state of California, which is a limited, albeit captive market.

There are plenty of other energy models out there that are far better and more accurate than Title 24 for predicting a building’s energy usage. However, none of them are acceptable for demonstrating Title 24 compliance.

Title 24 Inputs: Walls and Windows

So let’s take a look at some of the major inputs for Title 24 energy modeling. We start with the conditioned floor area only – this excludes attics, mechanical rooms, unheated basements, garages, porches, patios, courtyards, and crawlspaces.

Title 24 energy modeling inputs include the total conditioned floor area.

Next we need surface areas of all “opaque surfaces” – walls, floors, and roof. Anything bordering between conditioned and unconditioned space is counted; for example, the bottom floor is counted, but middle floors or walls between rooms are not. If the house has a lot of interior courtyards that are open to the outside, or floors that aren’t stacked neatly one on top of the other, it can be a bit of a chore to identify all the opaque surfaces.

There should be separate entries for every flat plane, i.e., every wall, roof, floor. You’ll have at least four walls, one for each direction. Further distinctions could include walls of different thicknesses; If it’s a remodel where only some walls are opened, there should be separate entries for walls being opened vs. walls staying as-is.

Remodels sometimes have conditions where some walls have to be counted, but they’re not being opened up, and they may not have much insulation. We have found that it’s much better to insulate ALL walls to a minimum than it is to insulate a small area of work and ignore the rest.

Title 24 energy modeling inputs also include wall areas, broken out by insulation level.

Windows have a huge, huge impact. Windows are great at letting daylight in, but they’re terrible at keeping out the cold on a winter day. Ordinary glass is also terrible at blocking the heat from the sun’s rays in the summertime. The more windows a house has, the more energy it will take to both heat and cool. Glazing surfaces can be grouped by wall – however for remodels where the windows are mixed, or where some windows have shading overhangs, sometimes we have to model each window individually.

Each window must be matched to the correct wall area, along with its performance metrics: the U value and the Solar Heat Gain Coefficient.

Title 24 Inputs: Heating and Cooling Systems

Title 24 energy model includes settings for common types of heating and cooling systems found in California homes. Each has its own efficiency measure, which can impact Title 24 energy compliance.

In addition to the surfaces, rated efficiencies of the heating and cooling systems are key. Different system types include gas forced air, hydronic, split system or heat pump. The difference between an ordinary gas furnace and a high-efficiency model can determine whether a home passes or fails. For a home that’s not passing, sometimes the simplest measure is to replace an older furnace even if you hadn’t planned on doing that.

Title 24 Inputs: Location, Climate, and Orientation

The home's latitude and solar orientation will impact its energy requirements, because the sun will shine at different angles and for different amounts of time depending on the season.

The home’s compass orientation (used in calculating passive solar benefits), city, and California climate zone are all required. The same house would incur different heating and cooling loads in Death Valley than in Tahoe.

Although solar orientation is a key principle in passive solar designs, it’s often not possible to optimize this if the project is a remodel, or is on a very small and predefined urban lot. I don’t think solar orientation has ever been a consideration in the laying out of streets or city lots, except to keep things on a north-south grid; most homes seem to be built to achieve maximum use of the lot, regardless of whether the sun shines inside or not.

For the purposes of Title 24 energy compliance, California is divided into 16 climate zones. The same house could perform well or poorly depending on the climate zone - and, something like solar orientation could help in one climate area more than in another.

Deep within the Title 24 software model are seasonal climate data for 365 days by region, which you cannot change.

What’s Not In the Title 24 Energy Model?

The Title 24 energy compliance software model has some intentional omissions that, for real-world purposes, one might want to include in setting a home’s energy budget. I’m not going to argue these points, but they should be noted for any brave readers who’ve actually gotten this far into the article.

Occupant behavior and preference. The house is modeled as if everyone keeps it at 72 degrees Fahrenheit during the winter day and night, and cools it to 68 in the summer, and no one ever goes on vacation. This is based on the ASHRAE comfort standard, which does have good reasoning behind it. In actuality, some people turn the heat down at night, or prefer not to heat the home so much.

Landforms. This is the single biggest omission which sometimes brings grief to projects that in the real world would be quite comfortably shaded by nearby mountains or hillsides. Title 24 treats every house as if it sat on a flat plain with no trees, landforms, or surrounding buildings. Thus sometimes it shows artificially high cooling loads. I can understand not counting another building, which could get torn down someday, but MOUNTAINS? Maybe they can’t figure out a foolproof way to do it, or how such a condition could be documented.

Fuel source (renewable or conventional). Title 24 is a measure of efficiency, but it doesn’t care much if you use renewable energy or gas. The thinking is, you should still build an efficient house, period, whether or not you cover the roof in solar panels. And, making the design efficient will reduce the number of panels you’d need anyway. However, the Title 24 manual itself states that one of the main goals of California energy policy is to reduce fossil fuel omissions AND to reduce strain on the utility’s power grid and infrastructure – since you have to do Title 24 whenever you change even part of a conventional heating system, I don’t see why they can’t reward self-generated power.

Appliances. For Net Zero Energy homes, Energy Star, and Passive Houses, part of the design process is to create a detailed energy budget that includes major appliances. Maybe even all appliances, large and small. Title 24 doesn’t care about your dishwasher or dryer, but your choices of equipment and when you choose to operate them can impact energy bills, so it’s still important for real-world consideration.

Green Building. There are energy efficiency standards, and then there are green building standards, and they’re not exactly the same thing. Title 24 could care less about VOCs, formaldehyde, or mold, because none of those conditions impacts energy use. Same goes for water conservation; landscaping and internal water consumption do not factor into Title 24 energy compliance. Other factors not considered include construction waste, habitat conservation, or proximity to public transportation – none have any effect one way or the other on heating and cooling within the building envelope. (It’s too bad about the public transportation – that one would be easy to put into the software model as a small additional credit.)

How Close is the Model to Reality?

The first thing is, Title 24 energy compliance isn’t intended as a predictor of real-world energy use or even comfort. The only intention is to compare all proposed projects to a standard to minimize energy-hogging features. One of the Title 24 models, Energy Pro, does include some cost-saving analysis and return on investment comparisons between different energy measures.

However even the most detailed prediction is just an educated guess. True energy nerds have been known to obsessively measure every aspect of their home’s actual energy use and temperature levels, in order to test their own assumptions and designs. A lot of today’s best solar designers were DIY experimenters in the 70s and 80s, and many of them freely admitted that their early mistakes were their best teachers. Building science itself is an evolving field. For example, air infiltration wasn’t originally recognized as being such a major factor in energy performance as it is now.

Thermal imaging can show where a building (or any body) is emitting the most heat. It can also show things like leaks or gaps in insulation, that otherwise wouldn't show unless someone opened up the wall. Those hot spots might be areas to consider for energy-efficiency upgrades.

The moral of the story is, don’t expect to get all the answers, because there will always be room for further discovery. Most of the green design practices of today are options with a cumulative effect: things you CAN do, but you don’t HAVE to use them all every single time. Each one should still be considered for appropriateness within each project.

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.

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.

After our recent interview with a GreenPoint Rater, several people wrote to us and we realized that since our last coverage in the Chronicle, many of our site visitors aren’t architects or building officials. They’re interested homeowners, or just plain interested.

Some confusion is perhaps justified. Even a cursory web search for “green building rating systems” turned up a pile of competing standards and organizations, some of which merely promote green building without issuing standards. (Mark, Alan, and myself have all contributed to the answers below.)

What is GreenPoint rating?

Green Point Rating is a system developed specifically for green building in California, with a checklist to guide a project while it is still in the planning stages, followed by several visits from a Certified GreenPoint Rater to verify that all measures are actually implemented during construction. Many jurisdictions, cities and counties are now both requiring the checklist at permit submittal, and a full GreenPoint Rating after construction.

GreenPoints includes various types of credits for water conservation and reuse.

The GreenPoint Rating system includes a wide series of recommended measures, and the home gets additional points for each measure that is followed. The final rating is a cumulative score of some possible 290-300 points. Of course, no home is ever going to get a “perfect” score by doing every possible thing. The intent is to provide enough options so that everyone can find at least a few improvements that they can do. And, according to my sources, it’s not that hard to even score the minimum of 50 points.

However, GreenPoint Rating is really about going beyond the minimum. All new construction must meet Title 24 requirements, but GPR is about exceeding the Title 24 requirements. When a green measure listed in the GreenPoint Rating system becomes part of the California Code, it drops out of GPR, because it is no longer beyond the requirements.

What’s the difference between a GreenPoint Checklist and a GreenPoint Rating?

The GreenPoint checklist is an Excel spreadsheet file that anyone can download straight off the BuildItGreen site. The checklist can serve as a guide to choosing among the many options and possibilities for green homes. On this same download page, you can find PDF manuals that explain each GreenPoint measure in greater detail.

If you refer to the checklist during the design stages, as Klopf Architecture did in this case study, your home can be more efficient both energy-wise and water-wise, with better indoor air quality. The checklist is what gets included with the permit submittal, if your jurisdiction requires or encourages the use of the GreenPoint Rating system.

The GreenPoint Rated Checklist includes yes/no items for things like topsoil protection, recycled or local materials, renewable energy, "extraordinary passive solar design", water conservation, and building energy performance.

Who’s behind the GreenPoint rating system?

The GreenPoint rating system was created by a non-profit organization called BuildItGreen, which is located in Berkeley, CA. BuildItGreen was founded by a wide consortium that includes public agencies, building professionals, construction manufacturers and suppliers, and architects. Its aims include raising consumer and industry awareness of the benefits of green building, and serving as a trusted source of information for designers, builders, manufacturers, municipal agencies, and the general public.

GreenPoints strategies for conservation of natural resources include material reuse, sustainably harvested lumber, and engineered wood.

How’s GreenPoint Rating different from LEED?

For one thing, it costs a lot less! Green Point Rating costs between $800 and $2000 to complete, and occurs fairly fast. LEED certification is far more elaborate, and can easily cost $10,000 to $15,000. It takes a long time, too.

Many of our design and engineering colleagues at the AIA have expressed the general opinion that LEED for Homes isn’t worth it, although they’re always quick to add that they support green building. And, one of our Title 24 clients is going for LEED Platinum on a remodel – so, in special cases, it might be worth it for the recognition.

GreenPoints gives community planning credits for walkable communities with access to public transportation.

What’s purpose of having GreenPoints? Why create a new system if we already have LEED?

Our guess is that LEED proved too cumbersome and expensive for anything other than large commercial or public projects. Despite its good intentions, LEED essentially put green building out of reach of the “average” homeowner.

By contrast, it’s not that difficult to achieve a baseline GreenPoint score of 50-75 points, even for the most basic of homes, lowering the barrier to entry. The GreenPoint system is a simpler collection of options and ideas, which are specific enough to be a real yardstick, yet straightforward enough that you don’t need advanced training to understand it – although to be a fully certified GreenPoint Rater, you do need a fairly strong background in architecture, construction and/or engineering.

What happens during a rating?

You’d most likely use the Checklist in conjunction with actual energy-efficiency improvements, or because it’s required for a permit submittal, and then get the improved home rated after the fact. However, if achieving a higher GreenPoint score is important for you, then it’s a good idea to involve a Certified GreenPoint Rater early in the design process.

GreenPoints encourages clean air through both better indoor air quality, and reduced air pollution.

Some jurisdictions are now require a GreenPoint Checklist to be submitted along with permit materials. The checklist usually doesn’t have to be filled out by a certified GreenPoint Rater, although there has been some reported initial confusion among Planning officials on this point.

Then, at specific points during construction, a Certified GreenPoint Rater comes out to your house and looks underneath everything to certify that the correct building products and techniques are being employed. After completion, the GreenPoint rater takes all the information and completes the scoring.

Why should I get my home GreenPoint Rated?

Increased home value, smoother permitting process – and, for professionals, green design credentials.

For homeowners, just having your home rated may boost the value or potential value of your home. Adding GreenPoint Rating to a home provides other professionals such as realtors, lenders, and appraisers with a reliable litmus test that this home not only exceeds California’s building and energy codes, but also is healthier and more environmentally friendly than a non-rated home.

GreenPoints encourages energy savings through more efficient homes and systems.

Architects who have GreenPoint-Rated homes in their portfolio will enhance their credibility with new clients who care about green homes. Statistics unearthed by our own Alan Hugenot indicate that 28% of homeowners doing remodels want more environmental features in their existing homes. In addition, 43.5% of new home buyers would be more likely to purchase a new home if it offered an energy-saving guarantee.

How does GreenPoint Rating help with a smoother permitting process?

Submitting a permit set with the GreenPoint Rated logo in it sets the tone in advance with building department officials and local governments. The GPR logo tells them that this residence is being built responsibly, and creates a favorable response with the building inspectors.

California’s first restored historic Green Point Rated Home. Claremont Courier photo: Gabriel Fenoy

Local governments are encouraged by state agencies to go above and beyond the minimum requirements in Title 24 in order to meet additional goals set forth in California Law AB32. California’s Climate Change Initiatives Law AB32 requires state agencies to develop a plan to reduce greenhouse gas emissions to 1990 levels, by 2020. Coincidentally, 2020 is the same year that all new homes in California are intended to be Net Zero Energy homes. Constructing GreenPoint-Rated homes that reduce a city’s carbon footprint makes good business sense, and thus building officials are predisposed to support plans with the GPR logo.

How widespread is GreenPoint Rating among building officials?

Building officials in both the Central Valley and the Bay Area have endorsed GreenPoint Rating. As of October 2008, 70 local governments had actively begun using GreenPoint Rating in their jurisdictions, and some 200 additional local governments were in discussion with BuildItGreen to begin implementation of GreenPoint Rating. Jurisdictions such as Stockton, St. Helena, Los Altos, all now require some level of GreenPoint rating, or at least a checklist, in order to apply for a building permit. According to John Klopf (case study), the City of Cupertino is actually willing to pay for the GreenPoint Rater for any home that scores 75 or above.

The "Greenbelt" passive solar design by architect Ralph Rapson isn't GreenPoint rated, but it could be.

When should I get my home GreenPoint Rated?

You have to get it rated if you’re getting a construction permit in certain jurisdictions. In other cases, a good time might be when you’re already planning some renovations, or you’re planning to put the home on the market.

How can the GreenPoint Rating system help me to turn my home an energy-conserving dynamo?

To really “green” your home, you will need to make informed decisions that match your personal priorities. Depending on which choices you make, you will need to involve various types of building professionals. For example:

• To improve heating and cooling efficiency, you might start by consulting with an engineer who’s accredited through CalCERTS, CABEC, or ASHRAE to offer home energy audits, find out where your home falls as of today, and then move forward from there.

• In some cases, a good contractor can help. In the Klopf case study mentioned previously, the architect did more than go through the checklist; he worked closely with Starburst Construction, a Certified Green Builder, to evaluate materials and and mechanical systems. Many of the GreenPoint credits come from use of proper construction techniques during building, so having an experienced green builder is essential.

• If you’re tired of high energy bills, it might even be time to go all out and convert your home to a Net Zero Energy home. The Monterey Energy Group, a residential mechanical engineering firm featured earlier on this blog, has completed 60 NZE homes to date.

• And of course – last but not least – if you’re considering a major renovation or even just a small addition, consider working with an architect to coordinate your remodeling efforts and maximize space-planning potential. After all, if you’re already making all this effort, why not improve your home’s beauty and comfort while you’re at it?

This LEED Gold home, located in South Carolina, is a giveaway home from HGTV.com

The good news is many of these professionals are also now becoming Certified GreenPoint raters, and if your GreenPoint Rater can’t provide one particular service that you need, they’ll most likely be able to recommend someone who can.

Does GreenPoint Rating satisfy San Francisco’s Green Building Ordinance?

SF’s Green Building Ordinance is mostly voluntary at this point, and only really applies to commercial buildings. We don’t know exactly when they will implement the standards with enforcement. It’s possible that they don’t yet have the personnel to carry out the task.

The Truro Residence, designed by Zero Energy Design, is a Net Zero Energy home in Cape Cod. Not all NZE or GPR homes look like this - in fact, any conventional home could be NZE and you'd never know it just from looking.

How can I find out the GreenPoint “score” for a particular home?

BuildItGreen doesn’t appear to have a registry of the ratings themselves, so you’d have to ask the owner or see if it was filed at your local Planning or Building Department. If it’s a sale property, ask the realtor. Just saying that a home is GreenPoint Rated doesn’t tell you enough specifics about how well it scored and why.

A few months ago, we had the pleasure of working with a GreenPoint rater on one of our recent Title 24 consulting projects. John Eckstein is a building professional with expertise in both home energy performance, and indoor air quality, particularly mold investigation. Since GreenPoint rating is still relatively new, we asked him what is involved in working with, or becoming, a GreenPoint rater.

At what points during the project does the GreenPoint rater get involved?

The earlier the better.  By getting a GreenPoint Rater involved in the early planning stages, simple changes can be made to the design that will have a more cost-effective impact on the overall performance of the home.  Two things that come to mind in this regard are duct layouts and Title 24.

The architect should consider the duct layout for the HVAC system while designing the home. We all know that the less bends there are in a duct, the better the duct will perform. Yet I cannot tell you how many times I have seen a beautifully designed home, but because the layout of the ducts was never considered, the HVAC contractor ended up having to route the ductwork in a way that was far from optimal.

This is an easy thing to address at the design stage, but the architect and the HVAC contractor need to talk. This doesn’t happen because of the way we design buildings in the USA. There is typically no HVAC contractor on board during the early design stages. A good GreenPoint Rater can help to address this.

Also, having a good Title 24 consultant is imperative. Many architects don’t realize that there is a huge difference in quality between different T-24 consultants, so they typically go for the cheapest person they can find, and then they get “boilerplate” calculations that don’t optimize the final T-24 in terms of detailed window schedules or other construction details.

Remember – each percentage point over standard on the T-24 calculations equates to 2 points on the GreenPoint Checkist. [Ed: so for example if your home exceeds Title 24 by 15%, you would achieve 30 points on your GreenPoint score] Optimizing T-24 is a great way to get a jump start on building a quality, energy-efficient home.

[Ed: Building to the GreenPoint checklist, even if you don't actually get the project rated or certified, will improve the efficiency of the design.]

What does it cost to get certified (for those considering adding this to their creds)?

The requirements and coursework has changed since I became certified, so I don’t know what it would cost nowadays. The best thing is to check directly with BuildItGreen.

What background and skills does someone need to be a GreenPoint Rater?

The obvious background in construction is important, but I also draw on my background as a consultant and my training in Psychology.

There is no such thing as the color “green”, there are only shades and each client will define green their own way. The GreenPoint checklist available from BuildItGreen has over 270 points available, so there is lots of flexibility to mix and match measure that meet the budget, energy efficiency, and environmental concerns of each client. A good GreenPoint Rater can help the client understand and translate their “green” priorities into the checklist.

The two faces of GreenPoint rater John Eckstein show that there is more than one way to be "green".

My background in sales and psychology are also helpful. In my own mind, I see my role as a rater as part inspector and part home “therapist”.  Just as a psychotherapist will work with a person to bring out the best, a GreenPoint Rater will work with a team of designers, contractors, and homeowners to bring out the best in the home. Being able to work with and understand different personalities and egos, and then communicate and motivate is probably the major role of a good GreenPoint Rater.

What seem to be the hardest issues for architects to understand, from your experience as a GreenPoint Rater?

There are all kinds of architects, so I don’t have a great answer. From my experience working with residential architects, many have a blind spot in relation to ventilation design and HVAC sizing and layout.

How can architects be better prepared to work with a GreenPoint Rater?

BuildItGreen offers a terrific training program called the “Certified Green Building Professional” (CGBP) program where architects can become certified.  This is a great way to get up to speed on the “why” behind all the measures.  Also, as a rater, I  can add a point on the checklist when both the architect and the contractor are CGBP certified.

Which jurisdictions really have it together?

San Mateo County is pretty good. They are working hard to understand the program and their outreach has been excellent about educating the community and contractors about the program. I always see people from San Mateo County at the training programs.

Los Altos Hills seems to have a well-thought-out green program.  I also see many of their staff getting trained.

Palo Alto has made green a priority.  They have a dedicated green program manager in the building department.

On the other hand, there are a few jurisdictions that have made getting a GreenPoint Rating mandatory for new construction, but they have done little to educate their desk staff or inspectors about the program.  As a result, I get calls from many exasperated homeowners and contractors who have been given lots of misinformation, which gives the program a bad name.

What is your own background, and how did it lead you to become GreenPoint Rater?

My father and grandfather were in the plumbing and heating industry.  I never valued it then, but being exposed to the HVAC industry at a young age has really helped me as a GreenPoint Rater. I also ran an indoor air quality and mold testing firm for a number of years.  I investigated hundreds of homes with air quality and mold issues that were caused by errors in the way the home was designed, constructed, or operated.  It sounds strange, but I think I know more about how a home should be designed because I have seen so many that have failed.

I lived in Japan for 13 years and lived in a variety of homes that were designed for a very different climate and culture. This had a major impact on the way I view homes and in the way I work with clients. Japanese trades tend to cooperate more effectively than I see here in the USA. It is huge generalization, but in my experience there there is less “pointing fingers” and less territoriality between the trades.

There are huge opportunities to improve the quality of construction if we could get the trades to think of the “big picture”. For example, an electrician who drills a 1/2 inch hole for a 1/4 inch wire should be thinking of air infiltration and then take the time to seal around penetrations.  Some plumbers install pipes right flush with the wall or stud, so it is then impossible to wrap the pipe in insulation.  Insulation and HVAC contractors should be involved in the job early, so they can plan ahead.

Many clients (and architects as well) have the impression that implementing green features is expensive.  How much does it cost to encourage the trades to talk to each other and to think of the big picture?

I am a HERS rater and do residential energy audits using HERS testing protocols. I also have trained with the California Building Performance Contractors Association (CPBCA). The CPBCA opened my eyes to building science and to treating the home as a holistic system of integrated parts.

I have worked on about 350 GreenPoint Ratings to date. It is funny, because I only took the orignial GreenPoint training because I interested in learning more. I never intended to become a rater.  It just sort of grew.

Do you have any nifty stories or cool projects to tell us about? What’s the coolest project you’ve seen thus far?

For me, the “coolest” green homes are the ones that are thoughtfully and tastefully designed. In my opinion, many of the things that make a home truly “green” are not so sexy, nor expensive.  Some very “green”, but not so sexy measures:

• Designing the home to consider passive cooling and heating.
• Considering the solar orientation of the home and then designing exterior shading, overhangs, tree planting to take advantage of that orientation.
• A well-designed, right-sized, and properly installed zoned heating system.

Do you have any pet peeves?

I really wish that the cities would take the time to really understand the program and to educate their staff and citizens before making these green programs mandatory.

Just when we thought there couldn’t be any more how-to manuals for green building – LEED, GreenPoint checklists, the Title 24 Residential Compliance Manual – along comes another one that might be the best one yet. The 2008 Residential Remodeling Guidelines from Regreen.org (a partnership between the ASID and the USGBC) is clearly written, persuasive, well-organized, and sensible.

(Above image used by permission of Dormer’s only Construction Corporation, based in Wyandanch, NY.)

It’s both holistic and practical, simple and direct. Here’s a slightly paraphrased version of their intro statement:

“It is easy and tempting to boil down green building to simply product selections [while] ignoring the challenges of green building as a process…Green building is almost always about how systems work together to reduce environmental impacts.”

This guide even addresses the “design” part of green design by asserting that beauty is part of sustainability, because if people like a building, they’ll be less likely to knock it down later on. Using less energy by itself is not enough, either. Good design means that it meets the user’s needs:

“…you cannot have a green project that is not also a quality project… For example, you can’t have just efficient lighting; it must also be effective lighting.”

Described as a “best practices” manual, it’s a method that includes structured questions and decision checklists to be addressed early on. It’s organized by remodeling project type (kitchen, bath, bedroom, living/working room, finished basement, building performance improvements, new additions, gut rehabs, energy retrofits, and outdoor living).

For each of these project type, there’s a predesign checklist, a scope section with a list of strategies to choose from, a slew of case studies to serve as templates for each type of project – and then you can refer to a complete “strategy library” with synopses of practices such as insulating your water heater or zoned heating controls. Each option is described along with potential issues – which might be the single most valuable thing in the entire guide.

There’s one other noteworthy aspect of a high-quality green building approach, and that is people skills. In a holistic design approach, you can’t just treat each system or assembly as a separate engineering task; you have to ask the clients what’s comfortable FOR THEM. Since many clients may not know exactly, the builder or designer must be skilled at eliciting this information, empathic enough to comprehend the client’s unique perspectives, and patient enough to allow sufficient time for this part of the process.

Nearly every week, we are asked why Title 24 does not give credits for electric water heating if that electricity comes from solar or other self-generated power. In fact, it seems that many of the renewable energy developments occurring now are not fully recognized in Title 24, not even in the 2008 code. We’re in the position of telling people that their homes, which are designed to consume very little conventional power, may have trouble passing the Title 24 code if those homes rely solely on solar electric for all their home power, heating, cooling, and water heating needs.

So why does T24 continue to penalize electric resistance heat and water heating in solar homes? Why does T24 not give credits for self-generated power (geotherm, solar, wind, other)? And why can’t our utilities buy back excess power from customers who generate more than they use? Wouldn’t this help to reduce California’s grid load, save California homeowners money, provide entrepeneurial opportunities, and reduce American dependence on foreign oil?

Title 24 History

California’s energy standards were originally mandated in 1974 by the California legislature, through a piece of legislation commonly known as the Warren Alquist Act. This act created the California Energy Commission and authorized it to develop and maintain energy efficiency standards for new buildings, and it specifically requires that these standards be cost-effective “when taken in their entirety and amortized over the economic life of the structure.” (Title 24 2005 Residential Compliance Manual)

According to the Title 24 2005 Residential Compliance Manual, Title 24′s stated intentions are the following:

• Save homeowners money
• Keep homes affordable
• Reduce strain on the power grid during peak times by reducing demand
• Stabilize California’s economy by buffering against sudden price increases
• Comfort (poorly insulated and drafty homes with oversized systems that cycle on and off are less comfortable)
• Reduce environmental pollution
• Reduce carbon emissions

California Energy Commission’s Response

I started with the California Energy Commission, which is responsible for creating and updating the Title 24 energy code. Why would the code ignore the potential of self-generated power to reduce demand for conventional power when our grid is already fragile? I spoke with Mazi Shirakh, P.E., M.B.A., a Senior Mechanical Engineer who serves as the Project Manager for Building Energy Efficiency Standards at the CEC, and who is also the Program Lead for the 2008 Standards update. Mr. Shirakh outlined the reasoning behind Title 24′s approach to alternative energies. (It is normally the Commission’s policy that individual staff members should not be named in articles and blogs, but in this case they’ve agreed to allow us to attribute directly.)

“The reason is that up until now, alternative energy technologies were too expensive when compared with more traditional energy-efficiency measures such as high-performance windows or air conditioners. While their costs remain high, PVs cannot demonstrate cost effectiveness as required by the law. We recognize that this is changing,” explained Shirakh.  “PVs are still expensive, costing around $8/watt. To install a 2Kw solar system costs around $16-$20K, whereas you can get a high-efficiency furnace or air conditioner for a lot less than that. However, the price of PVs has been steadily decreasing since the beginning of 2009. Assuming that this trend continues, there will be more possibilities for PVs in the future rounds of Standards. At around $2 or $3 a watt (including incentives) PVs would be much more competitive with traditional efficiency measures.”

Shirakh mentioned incentives such as the New Solar Homes Partnership, and I pointed out that such programs have nothing to do with Title 24′s internal scoring. If the intent is to reduce the load on the grid through less use of conventional power, why should an electric water heater that runs from PVs be scored the same as an electric water heater that runs on conventional power?

“The building must meet a certain efficiency levels first before PV or other on-site systems are considered. If we didn’t do this, there would be nothing to stop someone from building an inefficient structure and just slapping an array of PVs on the roof instead of other efficiency measures such as building insulation. And there’d be nothing to stop the owner from ripping out those PVs later on and running the building solely off the grid.” he replied.

OK, I’ll buy that for a dollar.

Alternative energy contractors are less inclined to accept this argument without comment, however. “That’s a spurious argument, in my opinion. Who’s going to take a building with a functioning solar system and rip it out?” said Gary Gerber of Sun Light and Power, a solar systems designer and installer. Another alternative-energy contractor, Greg Kennedy of Occidental Power, speculated that it was about centralized versus decentralized power networks. “Utilities are building big centralized power plants, with solar installations far out in the desert and then transporting the power over long distances. If that power were generated more locally, less of it would be lost during transmission. It’s really about who’s controlling the cash register.”

In a subsequent exchange, Shirakh clarified CEC’s position regarding Title 24′s approach to self-generated power: “Allowing proper credit for solar assisted electric water heating is one of the goals of the next round of Standards (currently known as the 2011 Standards). However, we need to be careful about how much credit is given to onsite generation measures; we still want to encourage buildings with efficient envelopes, mechanical, water heating, and lighting systems, even in the presence of PVs and other onsite generation systems. In addition, an energy efficient building will require a smaller solar system (less costs) and provides more comfort to the occupants. It should be also be noted that the Standards do allow a substantial credit for solar thermal water heating which can be combined with either natural gas or electricity. This is a mature technology and is widely available within the State.”

Shirakh was not familiar with fuel-cell technologies such as ClearEdge Power’s product offerings. However, he assured me that if we did any Title 24 documentation for a project that used them, we could contact the CEC for assistance.

Does Renewable Energy Comply with Title 24?

So, how hard is it to get a net-zero home to comply with Title 24? “Most are quite easy, because they are relatively efficient buildings already,” responded Dave Knight of the Monterey Energy Group. “The coastal areas and the hills are OK, but it is significantly harder to get a net-zero home to pass in Central California. California’s central climate zones are very hot, and the A/C load kicks in.”

Knight added, “From the very beginning, Title 24 mandated that solutions be cost-effective. In the past, some systems such as solar thermal could supply 80-90% of a home’s space heating load, but were seldom cost-effective, and it was complicated to predict how they would work. But they’re not looking at the current prices or the latest incentives. In the last few years, the prices of solar PV have dropped by 20-25%. So there’s three things coming together now: more efficient buildings, lower PV prices, and new tax incentives.”

So What Can We Do About It?

“The Grid-Tied Solar Electric home that we discussed at the AIA in San Francisco a few weeks ago is unbelievably simple, reliable, and predictable. And it’s cost-effective today. No matter what our clients’ motivation is, whether it’s reducing carbon emissions, saving on energy bills, or reducing dependence on foreign oil, there’s an incentive for them to convert their home to GTSE,” Knight responded, and went on to urge the design community itself to take on the task of change.

“I think the AIA should take the lead in building and promoting Net-Zero Energy homes. I mean, a LEED certification can cost six figures and require what seems like thousands of meetings. By promoting Net-Zero Energy homes, the AIA could push their own agenda without waiting for the CEC to catch up.”

Why Can’t We Sell Back to the Grid?

What about people selling their excess power back to the utilities like they can in Germany? “There’s a difference between a feed-in tariff and selling back the excess through net metering. A feed-in tariff guarantees or fixes the rate at which power is sold back. Net metering simply measures how much energy is used versus replaced. But, any excess you produce is a gift to the utility,” said Gary Gerber.

“There are actually several bills that have come up for this in the past few years, including one that’s on the table right now. Allowing PV owners to sell excess would offer several benefits. For one thing, it promotes a cleaner environment because it uses no fossil fuels. But just as important is PV’s potential to reduce peak loads at the hottest times of the year, since peak cooling times are also when the sun is strongest.”

The Politics of Renewable Energy: Left and Right

Politically, there’s an unspoken divide between liberal and conservative approaches to power generation. Conservatives tend to push for nuclear power and offshore drilling, whereas liberals are more likely to promote clean solar energy and lifestyle changes. “We don’t care, it’s about what really works,” observes Green Compliance Plus founder Mark English. “Knee-jerk ideologies are not useful.”

There have been a few reported accidents, and safety is a major concern for both operation and waste disposal, but overall France seems to have a good nuclear energy model. A formerly oil-dependent nation, France invested heavily in nuclear power as a response to the 1973 oil crisis – now they actually EXPORT power. (Perhaps rather than dismissing it out of hand, we could seek to enforce accountability by requiring all nuclear executives and managers and their families to reside within a mile of their own power plants?)

Having said that, the ideological debate does tend to polarize along party lines. Solar power is viewed as an expensive boutique technology espoused by rich liberals like Al Gore who don’t always practice what they preach (remember when his Tennessee mansion turned out to have a huge carbon footprint, even after he wrote such reams on global warming? What were you thinking, Al?) It’s also possible that conservatives haven’t invested as much in renewables and thus don’t stand to profit from increased sales of renewable energy products and systems.

Who knows? When it comes to solar energy, I’d like to think that a chance to save money on energy bills and perhaps even make money as an entrepeneur, would be appealing to advocates of free enterprise. And, the opportunity for America to reduce dependence on foreign oil should appeal to political economists and xenophobes alike. What are we waiting for?