A few months ago we published an interview with a GreenPoint Rater to de-mystify the GreenPoints system that was suddenly taking California building departments by storm. Like LEED and several of the current rebate programs, GreenPoints has tie-ins to Title 24’s energy compliance scoring, and so we’ve had to help our clients to interface with this new standard.

There’s another standard that’s been around for a long time – the Home Energy Rating System, or HERS. For the first time, we are having to tell our clients that they will have to do at least one HERS verification in order to meet the new 2008 standards of California’s Title 24 energy code. Suddenly, everyone had questions. What in the heck do HERS raters actually do, and what does it cost? Is this going to be a huge headache or a minor annoyance? What benefit is there to HERS testing apart from compliance? What does a person have to do to become certified as a HERS rater?

I’d make a distinction between green-building standards and energy performance standards.

• Green building is focused on the bigger picture, on quality of life, and on the entire life cycle of the building and possibly the surrounding community. Examples include LEED and GreenPoints.
• Mechanical/efficiency standards are focused on building operational performance and energy usage. In this context, the Home Energy Rating System, or HERS, falls into this second category.

What HERS raters do is make your home more energy-efficient by auditing its current performance levels and pinpointing areas of poorest performance. A few weeks ago, I looked at the CEPE roster shared by the California Association of Building Energy Consultants (CABEC). I was looking for people with dual or triple credentials in GreenPoints, HERS, and as a Certified Energy Plans Examiner (CEPE), since those are the three areas where we most often have to interface with our Title 24 work. One of the people listed on that site, Rob Lehman, is the subject of today’s interview. Rob is also listed on our Affiliates page.

In the text below, Rob’s answers are credited as RL, and editorial notes are shown as [bracketed italic].

What do HERS raters do exactly, and why is it important?

RL: HERS raters are special independent inspectors certified through a HERS provider, and ultimately by the California Energy Commission (CEC) to evaluate homes in California according to the Home Energy Rating System (HERS). These ratings include field verifications and diagnostic tests to determine existing efficiency levels for various energy-consuming components such as:

• Heating and cooling systems
• Supply and return air ducting
• Building envelope air infiltration
• Building envelope insulation quality

A HERS rater will also perform a comprehensive energy analysis of the home, including energy consumption for all daily living activities in the home. This evaluation includes the heating and cooling systems, and how the building components such as insulation, doors, windows, water heater, and lighting all affect the home’s energy efficiency. The information is entered into a computer program that calculates an energy rating for the home. All of the possibilities for improving energy efficiency are analyzed and prioritized according to which ones provide the most improvement relative to their cost.

This illustration shows where the bulk of energy loss occurs within a typical home: 40% through the roof, 36% through the floor, 14% through the walls, and the remaining 10% through window and door openings.

[HERS is nationwide, not just California. The California HERS program was implemented starting in 1999, and is used provide field verifications for energy efficiency programs. HERS Phase 2 or HERS II is the next stage in that implementation within the state of California. There is also a national HERS program sponsored by the Residential Energy Services Network (RESNET).]

How did you get into this work?

RL: I became interested long ago in do-it-yourself energy conservation and efficiency through Mother Earth News way back in the 60’s and 70’s, and dreamed of a day when smarter building methods would actually be used to conserve energy and help to save the environment.  When I realized the opportunities were out there to become a HERS rater, I joined right away. I have always dreamed of having an active and productive part for myself in energy and environmental conservation efforts.

Where can people find a HERS rater?

RL: People usually come to me through their builders. The public hasn’t caught on yet where to ask for Home Energy Rating Systems inspectors, but you can find HERS professionals listed on sites like CABEC, or through one of the three registered HERS provider organizations within the state of California:  CHEERS, CalCERTS, or CBPCA.

For our market space – residential low-rise Title 24 – what are the most common verifications solely for Title 24 compliance?

RL: The most common HERS verifications that I have performed for low-rise residential construction include tight duct tests and Quality of Insulation Installation, or QII. That’s my advice – start with the ducting and the building envelope.

A blower door test measures the amount of air infiltration within a home.

Some other HERS verifications that are also good to do, and which earn compliance credit within Title 24, include:

• Blower door test for air infiltration through walls, ceilings and floors
• Refrigerant charge management and verification in split system air conditioners and heat pumps
• Measurement and verifications in a/c cooling coil airflow
• Measurement of air handler fan watt draw
• Verification of high energy efficiency ratio (EER) for the air conditioning system, through component matching
• Visual inspection of supply duct location, where ducts are located within conditioned space
• Visual inspection to verify buried ducts or deeply buried ducts
• Photovoltaic installation verification

To qualify for Title 24 compliance, all of these measures require a certified HERS Rater to conduct a field test or visual inspection, and register the results with a HERS provider.

[A HERS provider is not a person, it's an organization such as CHEERS, that is certified by the State of California. You can earn compliance credits through HERS verifications if you use the performance method of Title 24, which employs a software model to simulate the building's energy performance.]

As time goes forward, I believe that people will have to use HERS verifications more and more, as a bolstering measure for Title 24 energy compliance. They will need the extra credits from the HERS verifications to obtain the Title 24 performance scores necessary for green building certifications such as LEED, Build it Green (GreenPoints), and Energy Star.

Are you finding that it’s harder to get projects to comply under the 2008  Title 24 code? What sort of measures are you having to advise your clients to take?

RL: Numerous changes within the 2008 Title 24 energy code have raised the standards for higher energy efficiency in California homes to roughly 15% above that of the 2005 energy code.  And this is just to obtain a passing score of “0″. All this is being driven by AB 32, the Global Warming Solutions Act of 2006. The State of California will continue to tighten up requirements in future code cycles, which happens every 3 years.

I advise my clients to take advantage of the HERS verifications that will help them the most, within their climate zone. In San Francisco, there isn’t a tremendous demand for cooling such as there is in Fresno. So perhaps instead of recommending a refrigerant charge management test, I might recommend a blower door test for whole house air infiltration, to identify problems with a poorly performing building envelope.

California has 15 climate zones, each with different heating and cooling loads. For example, San Francisco is Zone 3, San Jose is Zone 4, both relatively moderate. Livermore, which isn't that far away, is Zone 12 - much hotter.

I have found that including even one HERS verification yields a very significant improvement in the Title 24 energy report score. If the client plans on obtaining a green building certification through a program like GreenPoint Rated or LEED, a Title 24 performance score of 15% better than “0″ is mandatory.  Considering that the 2008 Title 24 requirements are already 15% tighter than before, plus the additional 15% over baseline required for Build it Green or LEED, it is easy to see that employing a HERS rater may be essential for achieving all these goals.

Compliance aside, what are the most worthwhile verifications or services that a HERS rater can do? Why would someone hire a HERS rater aside from Title 24 compliance?

RL: Saving energy! That translates into lower utility company bills, month after month. Everything that a HERS rater can do is an avenue for improvements that will save money. Here in the Bay Area, I recommend starting by investigating the building envelope and duct systems.

A duct blaster test in progress. This duct lying on the floor looks a bit like a python at the zoo.

I recommend starting with the ducting because the standard methods of installation for HVAC ducting throughout the years has not been favorable to tight, efficient ducts that have low air leakage. I’ve heard figures quoted in training workshops stating that 30% leakage in a typical ducting installation is routine, and the air infiltration even in some newer homes is still very poorly controlled. That is a tremendous waste of valuable heating or cooling BTUs! All that expensive conditioned air could be going into the attic or under the crawlspace, or out through holes and gaps in walls, floors, and ceilings and not into the home where you want it.

That’s crazy! Are ducts really that poorly installed every time?

RL: Duct leakage is an issue especially in tract homes that are built by contractors working under the gun to finish the job as quickly as possible. Another problematic practice has been that the so-called “standard” for duct sealing for many years has been to use duct tape for sealing the ducting to the sheet metal connectors. But, most duct systems are in the attic, which get as hot as 140 degrees in the summer time. Duct tape adhesive isn’t designed to withstand these temperature extremes, and it dries out.

Ducts, plenums, air handlers, and connectors should be sealed with mastic on all joints and seams.

OK, so tract homes are one thing, what about custom residences? Do they have leaky ducts, too?

RL: Even in custom-built homes with higher standards of care, it still happens. The standards say not to depend on duct tape, that instead duct mastic should be used. [Mastic is a high-strength flexible adhesive that can tolerate temperature fluctuations.]

Don't use duct tape to seal your ducts - use mastic. There are plenty of web sites to show you how, although if you've never done it before, consult a professional.

What is Title 20 and why do HERS raters care about it?

RL: Title 20 is a piece of California legislation that empowers the California Energy Center to approve the software and protocol necessary for HERS II Raters to conduct energy audits, in order to tie those audit results more closely into various new incentives. There have been energy-auditing businesses and HERS provider organizations offering their services for years now, but until now they have not been regulated by the State. One reason to do so now is the increasingly complex interrelationships among the various energy-related incentives, rebates, and tax credits with Title 24’s energy compliance scoring system.

Title 20 is new legislation, very recently passed in California, which is now in the implementation stage. My HERS Provider, CHEERS (which stands for California Home Energy Efficiency Rating System) is within one month of being available to train and certify HERS II Raters to audit and report energy scores for various incentives, rebates, and tax credits.

Are there other pieces of legislation in the works that we should know about?

RL: Local government financing of homeowner energy improvements through AB 811 may require a HERS II Rater to perform various tests to show how much energy efficiency improvement has actually been achieved. The Federal Home Star Program may require similar verifications.

Rumors of mandatory energy score reports for real estate transactions when selling a home in California are probably not going to pass as law anytime soon, because there has been a lot of opposition from the real estate lobby.

What do general contractors and HVAC contractors have to do differently now under the new Title 24 requirements?

RL: If there are required HERS verifications for any portion of the scope of work involved for a permit, General Contractors and/or HVAC Contractors will have to hire a HERS rater who will register the HERS verification measures online in order for the contractor to obtain a building permit. This requirement will take effect October 1, 2010.  The documentation for the HERS verification (included on the CF-1R Title 24 report) must accompany the application for the building permit, and be submitted to the building department for that jurisdiction.

[These HERS verifications consist of whatever tests were called out originally on the Title 24 report also known as the CF-1R, which was submitted earlier to the planning department for site permit.]

In terms of the CF-1R and CF-6R connection, who’s responsible for what? Where is this all-encompassing HERS data repository, anyway? Who owns and maintains it? How can an architect look up the status of his or her project to see if the project was properly registered? If the HERS rater doesn’t follow through on the reporting, what does the architect have to do to follow up?

[Each registered HERS provider maintains its own separate online registry. Again, these providers are organizations, not people. There are three HERS providers in California: CHEERS, CalCERTS, and CBPCA. Ask your HERS rater which provider he or she is certified through to discover where your project will be registered, and check that provider's web site.]

RL: There are actually three compliance-related forms for Title 24 now: The CF-1R, the CF-4R, and the CF-6R.

• The CF-1R (the Title 24 compliance report) indicates which HERS measures have been specified for credit in the Title 24 energy calculation. Both the architect and the project coordinator are responsible for knowing what is on the CF-1R in terms of how the building and systems are modeled, including specific performance data for products such as furnaces and windows, and any HERS verifications that are specified. The architect should communicate this information to the other parties for follow-up as the project schedule requires.

• During the course of construction, the owner of the project, or his or her contractor, is responsible for ensuring a successful verification by a HERS rater for each measure listed on the CF-1R.

• To prepare for each HERS verification, the contractor (general, electrical, solar, or mechanical) furnishes the HERS rater with a CF-6R, describing the portions of their work or installation that need to be verified. This could include ducting, an HVAC system or component, solar photovoltaic arrays, or insulation in the walls, floors, or attic.

• The HERS rater is responsible for performing the verification and registering the results (pass or fail) with his or her HERS provider’s online registry within four days of performing the test or inspection. These results are also known as the CF-4R report.

• The building inspector (building, electrical, mechanical) is responsible for collecting documentation certifying that the HERS verification is complete, approved, and properly registered before signing a final inspection.

What’s the best way to ensure that the tests happen at the right time during construction?

[The general contractor or construction manager should do the following:

1. Make sure that they have accurate information about the HERS verifications that are required for the project, and
2. Include both the HERS verifications and any pre-testing at the appropriate time in the construction schedule.

For example, the ductwork can be pre-tested prior to completion of construction, but it will be an extra task for the contractor to do so. Since most contractors do not own the duct testing equipment themselves, they may need to have another HVAC professional (the HERS rater can't do it) do some pre-testing prior to the "official" test, at a time when the ducts are accessible for additional repair if needed. However, if the contractor waits for the official HERS test and the ducts don't pass, they may have to pull off sheetrock in order to address and repair any deficiencies.]

Let’s go through each of the tests individually and describe what’s involved.

What happens during a duct blaster test?

RL: Also known as a verified air leakage test, a duct blaster test is designed to test and document the air-tightness of forced-air duct systems. It takes about 1 to 2 hours to do.

Why is it that the only photos I could find of duct testing all show men?

In this test, the HERS rater attaches a calibrated air flow measurement system directly to the duct system in a house, typically at a central return, or at the air handler cabinet. With the remaining registers and grilles temporarily taped off, duct air tightness is measured by either pressurizing or depressurizing the duct system and precisely measuring the fan flow and duct pressure. The findings result in a percentage of leakage for that system.

For new homes, a leakage of 6% or less is the threshold to pass. An existing home needs to achieve a leakage rate of 15% or less. In some older homes, however, the ducting system may be largely inaccessible for repair. For these cases, a 60% improvement after failing the initial test may be allowable.

This is an example of a duct tester machine that might be used for commercial buildings. This one is a PANDA 311 Series from TSI.com. It doesn't look all that scary.

To prepare for this test: inspect your ducts ahead of time. Do you see old duct tape? Any mastic used?

For architects or private homeowners doing remodels, where this test may be specified to achieve Title 24 compliance but where no work is actually being performed on the HVAC system as part of the remodel, how do we know it’ll pass and what can we do if it doesn’t?

RL: Have an HVAC contractor come out and inspect it, pre-test it himself. Then the HERS rater can come out and officially test it.

Are there situations where a house will NEVER pass a duct blaster test?

RL: Well, if you’re using the prescriptive method of Title 24 compliance, duct testing is a mandatory measure for additions with over 40 new feet of ducting. However, if the home has asbestos in the system, it’s exempt.

But let’s take another example. Let’s say that this test has been called out, and it’s an existing home, an older home, with an alteration that has triggered a Title 24 compliance report. Let’s say that we need to use the performance method for Title 24, because we’re adding too much glass. We needed the credit from the duct test to get a passing score on the Title 24 report back at submittal time. Now we’re in construction, and it’s time for the actual test. What if it doesn’t pass, even with a 60% improvement on the second try?

My answer would be that you can’t get even a 60% improvement, that means the ductwork is very poor and the homes heating and cooling will be extremely inefficient. The homeowner should consider whether he really wants to keep throwing good money after bad.

What happens during a blower door test?

RL: A home’s air-tightness is measured with a diagnostic tool called a Blower Door. The Blower Door consists of a fan that is temporarily sealed into an exterior doorway coupled with calibrated pressure measurement equipment. The fan blows air out of the house to de-pressurize the home. This negative pressure differential pulls air from outdoors in through any holes, gaps, improperly sealed penetrations in the building envelope, or locations where weatherstripping is loose or missing – to name a few.

Blower Door tests are typically performed at a pressure difference of 50 Pa (0.2 inches of water column) and the findings are measured in Cubic Feet per Minute (CFM). The CF-1R form (the Title 24 report) has the minimum and maximum allowable rates indicated, and the test must show a rate that falls between those figures.

To prepare for this test: Seal off all openings and drains. Close all the windows, put stoppers or plugs in the sinks and tubs, seal off range hoods and chimneys, and plug up any other hole you can find.

So how can you pinpoint where air is coming in? Is there any equivalent to the thermal image test for heat loss?

RL: Not really. But you should look for obvious signs first, like loose weatherstripping. Caulking can help. Thermal imaging won’t help except in some cases where windows may be leaking around the seals or frames. Today’s windows are manufactured with tighter control and they’re better performing with regard to air infiltration. However, window installation may be an issue. Look for cold spots around window openings if using thermal imaging.

Thermal imaging can be an aid in determining where air leakage is causing cold spots. However, you can't always tell what is causing a spot without further investigation. It could be air, moisture, or thermal heat loss.

For thermal imaging to work, you need to do it on a cold day so there’s a visible thermal difference between the interior and exterior temperature. Also, any cold spots you do see may or may not be due to air infiltration.

Why does the air infiltration rate have to fall between two numbers? Isn’t lower always better? Don’t we want to create an airtight home?

RL: A home can actually be too airtight as well as too loose. Some newer homes are so airtight that they can have problems with moisture buildup, which can in turn lead to mold.

I thought mold was mostly a problem in very humid climates, not in California.

RL: If the home is tightly sealed and it also has high-humidity devices such as spas, aquariums, greenhouses, or even if the occupants do a lot of cooking, it can develop serious mold problems, even out here.

What is an Verified Insulation Quality test?

RL: A Quality of Insulation Installation (QII) verification is a visual inspection by a HERS rater to verify optimal quality in insulation installation. The HERS rater verifies the following:

• The insulation is of the proper R-value and type specified in the architectural plans and on the CF-1R Title 24 report
• The insulation coverage does not have any voids or gaps, nor any compression where the insulation is restricted from achieving its full thickness
• All pipes, wires, etc. that are in cavities where the insulation occurs are covered with non-compressed insulation in front and in back
• All electrical boxes are carefully cut out in the insulation in order to provide a tight fit with no gaps or holes

In other words, the QII inspection is looking for the installation to be pretty much letter-perfect, so that the home performs up to what the insulation manufacturer is specifying for their product. The reality is that most insulation is installed by subcontractors who are seeking to finish the job as quickly as possible.

A HERS rater can verify that insulation was properly installed by checking that the right insulation product was used, and that the insulation was applied evenly, without gaps or compression.

This verification is more cumbersome and involved that most other HERS verifications, because the HERS rater might have to make several inspections as different parts of the building are framed. For example, under-floor insulation has to be viewed before the subfloor goes on top, wall insulation should be viewed prior to installing the drywall, and corner cavity insulation has to be viewed from the exterior.

Can you do this test using thermal imaging if the walls are already closed up?

[For the purposes of Title 24 compliance, the QII verification itself has to be visual, with the walls opened up. However, if you are investigating a home's energy performance, thermal imaging can pinpoint problems that would otherwise be invisible.]

Thermal imaging shows missing insulation in this ceiling where it meets the wall - something that you can't see with the naked eye. In this case, what we're seeing is the building's cooling performance on a hot day, and the missing insulation shows up as a "hot" spot.

Where are the most common spots to find insulation gaps?

RL: In addition to the spots described previously – areas around electrical boxes, pipes, wires, and small building cavities – consider these areas as well:

• Behind the tub or shower
• Fireplaces and chimneys
• Skylight window wells
• Exterior edge between building floors
• Interior/exterior wall connections

This last one is important and hard to get to. In places where there’s a connection between an interior and an exterior wall, there will be a three-stud channel that’s typically filled with dead air, and no insulation. A 1.5″ wood stud has an R-value of only 2 or 3, while the mandatory minimum is R13. Insulation is typically installed from the inside, but for these channels, you have to get to them from the outside.

How do you remedy uninsulated spots inside a wall channel?

RL: To remedy the omission of insulation in a wall channel, you have to address it as the carpenters are framing the house. For example, they could cut and install rigid foam insulation. During a QII inspection we’d have to come out and see this part as it occurred.

What is a refrigerant charge test?

RL: The refrigerant charge test is a HERS verification for split-system air conditioning systems, and ensures that the air conditioner has an adequate supply of refrigerant to work with. The amount of refrigerant in the system can dissipate over time through leaks, and if it gets too low, the system’s overall efficiency suffers, possibly even shortening the life of the system. If the refrigerant level is adequate, the system is considered to be fully charged.

There are three ways to verify refrigerant levels.

• A non-intrusive test that analyzes the superheat and the temperature drop across the cooling coils, and compares that information to referenced values. With this information, the refrigerant charge can be calculated. It’s cumbersome to do because of the math, but worthwhile if you depend on your A/C system for comfort.

• A more intrusive method, less frequently used, is to attach a simple pressure gauge to the A/C system to get a direct reading of the refrigerant level within the system. However, this method also requires the HERS rater to obtain a certification from the EPA, because if the refrigerant leaks out, it can damage the environment.

• Within the next few years, manufacturers will begin installing a CID (Charge Indicator Device) with newer models. At this point, a simple reading of that gauge will be all that is necessary to verify the refrigerant charge. However, manufacturers have not provided these devices in most models as of yet.

Refrigerant charge verification is a mandatory prescriptive Title 24 energy calculation compliance in climate zones 2 and 8-15, but when running the performance method of compliance, it can be a selected HERS verification in all climate zones.

To prepare for this test: If you’re doing this test to meet Title 24 compliance requirements, you need to have a HERS rater do it. But, a pre-test can be performed by any HVAC contractor. If you’re not sure the home will pass, you can have an HVAC expert check the system first, and fix anything that needs attention, so that you’ll know the results of the “official” test beforehand. Because of their status as independent inspectors, however, HERS raters are not allowed to fix or change anything themselves. All they can do is run the tests and report the results.

I can see where a refrigerant charge test would be worthwhile for an older A/C system, but what about a brand-new one?

RL: Even with a brand-new A/C system refrigerant charge can be a problem particularly with split systems. In a split system, you have a compressor outside and a suction and pressure line running to an air handler inside. This line can be rather long, and if there isn’t enough refrigerant in the system, it can take enough to fill this tubing that there isn’t enough in the system overall.

OK, say you’re a developer, you want your latest project to be GreenPoint Rated, and to get more points you want to boost the Title 24 performance score on all the homes. To this end, you have opted to include HERS verifications such as the refrigerant charge test in order to gain additional Title 24 compliance credits. How would you go about pre-testing if you had a whole group of tract homes and you need for them all to pass the refrigerant charge test?

RL: In a tract home situation, an HVAC contractor can use sampling during pre-testing. The HERS rater will sample test also, in groups of 7. Bigger builders should realize that HERS raters are an asset that they can use to test and verify different components of construction.

What is a fan watt draw test?

RL: A fan watt draw test is done on air conditioning systems. It’s a simple measure of the energy consumed by the cooling coil fan, and referencing this to acceptable maximum values as shown on the Title 24 report.

What is a verified air flow test?

RL: This test measures the rate of air flow through the ducts. There are several ways to measure, but I am most familiar with the use of an air-flow capture hood, measuring the airflow with all registers open and the filter installed, and comparing the flow rates to be equal to or surpass the duct design criteria of 450cfm/12000 btu (1 ton).

What is an EER verification?

RL: An EER verification matches air-conditioner components for high functional efficiency as a group. This verification applies to split systems, where the air handler, the outdoor compressor, and the cooling coil can all be from different manufacturers. The verification looks up the make and model number for each of these components in a CHEERS online software application that contains data on how efficiently each of these components actually works with the others.

Is the EER verification a pass/fail test? What do you do if it “fails”?

RL: It’s pass or fail. What we do is match up the components for high EER compatibility. Either the proposed system makes it or it doesn’t. For example, suppose you have a system design that calls for a Carrier compressor, a Train air handler, and a third-party cooling coil. We do an EER lookup and it turns out that the off-market cooling coil was lousy pick.

At this point, you can remedy it in one of these ways:

• Call the contractor and tell him that the components don’t match, and give him some other options that do match.
• Re-calculate Title 24 report and pick another HERS measure based on what the project will best support.

How far off can they be in terms of efficiency if they’re not well-matched?

RL: I’m going to go out on a limb and give you a rough estimate, and say that mismatched components in a split system could degrade overall system efficiency by as much as 10-15%.

Is the EER verification something that you’d have to think about way ahead of time, during project design?

RL: Yes, this is something that should be considered early on. The architect or the mechanical systems designer should contact a HERS rater prior to specifying these components. It can stop you from making a bad purchase. Then, when you add this as a verification for Title 24 compliance credit, you can be confident that your system components can perform together as well as expected.

What is the maximum cooling capacity test?

[Usually recommended for commercial buildings. We're going to punt on describing it here, because it's rather complicated.]

What is the supply duct surface area reduction test?

RL: This is a verification measuring the efficiency of the duct design, again mostly done on large commercial buildings with very extensive HVAC systems. The HERS rater physically measures the duct system as installed and checks this measurement against the calculated allowable area of duct surface from the Title 24 report, and verifies that the existing duct systems meets this allowable criteria.

What are the visual field inspections that apply to duct systems?

RL: There are several inspections related to where the ducts are located and how well they’re insulated. All of these inspections are credits towards achieving a higher Title 24 performance score. The two buried-duct inspections only apply to ducts that are located in the attic.

• Buried ducts: The HERS rater verifies that the attic supply ducts are buried under the required R-value insulation, and that the ducts make contact with the ceiling sheet rock. Signs must be visible that say “caution, buried ducts” [so that anyone doing subsequent work on the home doesn't inadvertently damage them]
• Deeply buried ducts: In addition to the buried duct requirements as described above, the HERS rater verifies that the attic supply ducts have an additional R-25 insulation over them if fiberglass insulation is used, or R-31 for cellulose insulation.
• Ducts in conditioned space: This test applies only to projects where the ducts are located in conditioned space, rather than in the attic or a crawlspace. The HERS rater does a visual inspection to verify that 100% of all supply ducts are within the conditioned space envelope.

[Radiant barriers, which can earn compliance credits in Title 24, are verified by a building inspector, not a HERS rater.]

Under what conditions would any of these tests NOT be advisable?

RL: The climate zone for each project needs to be considered to get the best bang for the buck. In other words, tests that focus on air conditioning may not be advisable in climate zones where there is little demand for cooling.

[They don't buy you as much on the Title 24 score, either. For example adding a radiant barrier in San Francisco does nothing to improve a home's Title 24 performance score, but adding one in Livermore or Los Angeles certainly does. ]

What happens if a project fails a HERS verification?

RL: The HERS rater has to submit the results to the HERS registry as a failure.  The necessary repairs should be done by the contractor, and then the HERS rater is called back to perform the test again.

When does each of these tests occur in the project cycle?

RL: Various stages. The important issue is usually to observe a complete and finished component for verification, prior to its being hidden by subsequent construction. One example is the verification of quality of insulation installation (the QII test), which may require several trips. Duct verifications are best done after all or most of the construction activity is completed, and there is no possibility of workers subjecting delicate items such as ducting to damage.

How much do these HERS tests cost?

RL: Well it depends in part on the size of the building and how cumbersome the test is to perform. A duct blaster test might start at $250-$300, because it can be done in one trip and it only takes a couple of hours. Some duct blaster tests are more challenging than others. A QII insulation test, which requires several inspections over a few weeks’ time, could be more.

How can the architect, owner, and builder ensure that the project will pass on the first try?

RL: Perform your own pre-inspections and employ expert help prior to the test date to prepare the components for testing. For example, good HVAC contractors will often test their own work anyway, although many don’t care enough about quality to do this. But, they should.

Compare it to smogging your car. Emissions is a state test, and it’s pass or fail. You can go to a mechanic ahead of time for pre-smog testing to find out if you’ll pass, and get any needed repairs done prior to having the official smog check.

"Will this cardboard box pass Title 24?"

What do architects need to know about working with local building departments?

RL: Their compliance review starts with the CF-1R form, which is the Title 24 compliance report. But most people don’t know how to read a CF-1R report. Even architects, building officials, and plan checkers don’t always know every aspect of compliance.

Building departments can’t interfere with HERS verifications, which is a State-level program. However, with the increasing levels of reporting and inspection, it will be harder to do last-minute equipment substitutions.

[One thing to note is that Title 24 reporting relies on specific stated performance criteria for products ranging from windows to water heaters, and any substituted product needs to have an equivalent or better efficiency rating. This means that the person responsible for selecting equipment and products must be fully aware of any assumptions that were used when preparing the Title 24 report for the project.]

Any famous last words?

RL: Here’s one thing you should know: All three of the official HERS providers are mandated to do follow-up inspections to check up on their own HERS raters. So, the homeowner could get a call or a letter notifying them that this is happening. Usually they’re OK with it, it gives them reassurance that the system is really working as intended.

Green living is sometimes viewed as a sacrificial process whereby one by one, all our pleasures and comforts must be set aside in the name of saving the planet: walking instead of driving, sweeping instead of vacuuming, home cooking instead of take-out, turning the thermostat down in the winter while our hands and feet turn into blocks of ice, low-flow showerheads designed by bald men that take forever to rinse the shampoo out of a long-haired-girl’s mane, limiting one’s diet to only locally available seasonal produce (which could be nothing but cabbages if you live in Chicago), calling three hardware stores to find one that carries low-VOC paint, giving up meat because it takes too much grain to feed a cow, trudging everywhere with a backpack filled with stuff that otherwise we could just keep in the car. In essence, the increased physical hardship comes from asking our own bodies to start doing more of the work. And what’s our reward? A nice warm feeling of altruistic glow, and maybe a slimmer figure.

Efficiency is often seen as achievable only at the cost of comfort – some of us East Coasters remember shivering through the 1970s oil crisis as our dads re-defined 58 degrees during the day as “normal” and turned the thermostat down at night till the pipes froze, and our mothers finally complained. Well, so what? What’s the big deal? We all have to give up something. Well, the problem is that this “fix” didn’t really fix anything. Reducing consumption is not the same thing as having an efficient building, and neither approach presents qualitative factors like comfort or contentment as worthy of consideration.

It’s time we started measuring the benefits, started quantifying the value of comfort in both human and performance terms. After all, a bottom line applies both to corporate and to individual operations, even if the qualitative benefits of “improved morale” and “comfort” aren’t seen as “adding value”. People with severe allergies and asthma can already tell you exactly how much more productive they are in a mold- and chemical- free environment when they’re not gasping their life away, but what about the rest of us who can breathe diesel fumes all day with nothing worse than a little nausea?

Cats have long known how to enhance their own thermal comfort through reclaimed heat from TVs and other appliances.

Current Focus Is On Efficiency Alone

California’s energy code requires efficient buildings in order to reduce fuel consumption, reduce peak demand, and – yes it’s a stated goal – reduce fossil fuel consumption as well. Title 24 energy compliance trade-offs in residential designs are usually a matter of running the proposed design through a software model with different options, with an assumed average air temperature that is not configurable, to simulate the building’s performance throughout the seasons for a specified climate zone.

Title 24 seeks to make homes more efficient so that they leak less heat in the winter. Infrared photography shows that this home is losing heat through the windows and the attic.

If the proposed design does not meet compliance standards, one can weigh various building improvements against the costs and time needed to achieve each measure. Is it cheaper to replace all the windows or to upgrade the furnace and add some field verifications? Does it make sense to add a radiant barrier to the roof, or would it be better to spend that money on better wall insulation?

On paper, it’s the same either way. In practice, however, which option you choose can have a big impact on the comfort of the occupants – who may be your own design clients. Every time they sit in their patio, or in their kitchen, or in a reading nook looking out the window, it’s an opportunity for them to remember their architect with fondness. However, if every time they sit near their picture window they catch a chill, they’ll remember that, too – especially if they’re me. I’ve spent far too much of my life in buildings that were too cold for me, and most of it was bad design – needless discomfort. (In office buildings, the chill was exacerbated by inappropriate professional dress codes that required suits, pumps and nylons when a wool hat, a big bathrobe and slippers would’ve saved me countless weeks of colds and sinus trouble.)

Contemporary lifestyles presume that people can comfortably wear light clothing or go barefoot indoors, even in winter. However if the walls or the floor are cold, this home will feel much colder even when the air temperature is the same. That wall of glass just visible on the left could make it chilly just to sit on the sofa, if it were cold enough outside.

The thing is, indoor air temperature is easier to measure, and that’s what Title 24 takes into account. However, the indoor air temperature alone may not be enough to ensure comfort. Other factors, such as humidity, air movement, temperature of surfaces in direct physical contact with the user, the occupant’s level of activity, and radiant heat transfer from windows can make a huge difference.

So how the heck do you measure something as individual and subjective as “comfort”? How are these “findings” actually validated in practice? And how can the proven findings from this type of research be useful for residential designs to go beyond energy compliance? For this article, I visited the offices of Loisos + Ubbelohde in Alameda, California.

Advanced Modeling and Thermal Controls – Is It Really Any Better?

When most people hear words like “daylighting” or “integrated facade systems” they think of the elaborate sensors and controls that are increasingly employed for commercial high-rise buildings to reduce heating and cooling loads and ensure optimal light levels, mostly without human intervention. Of course, the public then hears of supposedly cutting-edge “sustainable” buildings that are no more efficient or comfortable than the old, wasteful kind – at least from the point of view of the occupants themselves.

An "old-school" skyscraper on the left by Louis Sullivan is a precursor to the modern curtain wall, but at least the windows still open. The all-glass facade of the Prudential building in Boston - famous for occasionally shedding windowpanes onto nearby sidewalks - incurs high heating and cooling loads.

The usual complaints are the lack of manual overrides and the general inaccuracy or insensitivity of these control systems to what is actually happening at different points in the building. People can’t open the windows for air or control for glare on their own, and they don’t like it. I personally spent years in offices where we taped the vents closed when they blew frigid air down our necks in the summertime – and then the management would come around at night and open them up – then the next day the war would continue, along with incessant bouts of colds and flu.

(Apparently these systems are a lot smarter now, and they actually DO know when the sun is shining in each window of a 15,000-window high-rise. At every minute, for every single day of the year. Just like Stonehenge! But that’s a topic for another article. Meantime, back to comfort.)

The New York Times Building by Renzo Piano incorporates a state-of-the-art multi-layered skin, as well as advanced daylighting controls that know exactly where and when the sun shines into each window, all year round. Loisos + Ubbelohde worked on the daylighting.

Who’s Using Comfort Research Now?

The firm of Loisos + Ubbelohde takes these daylighting criticisms seriously enough to address user comfort – and user behavior – using fairly sophisticated measures developed in conjunction with ASHRAE and the Daylighting folks at the Lawrence Berkeley National Laboratories. Apparently it *is* possible to measure something as variable and subjective as “comfort” with enough precision to make design decisions based on it.

My first questions to the folks at Loisos + Ubbelohde were:

• How do you know that these comfort predictions are valid?
• How do you explain your findings to your clients, who may not have the scientific background to understand all the reasoning behind it?
• How can you clearly and convincingly demonstrate to your client the VALUE of occupant thermal comfort?

Typical office workers huddling together for warmth.

San Francisco Office Building Example

They say a picture is worth a thousand words. So I’ll start with three pictures from a recent analysis done by Loisos + Ubbelohde for an office building in San Francisco. These three color-coded images show how much usable floor space you lose by having clear glass windows in the wintertime that draw radiant heat out of the room, and also from anyone who’s sitting too close to the glass. Basically, if you sit too close to a cold surface, you’ll feel colder – even if you’re not actually touching it, and even if the actual air temperature is the same. A consistently cold surface can, through radiant heat transfer alone, literally suck the heat out of your body.

Each image shows the same office space with a desk, with three different curtain-wall options. The color-coding indicates the Mean Radiant Temperature (MRT) which is a combination of air and radiant temperatures. The yellowish zones are comfort zones with an MRT of 71-72 degrees – neither too hot, nor too cold, for the majority of individuals. Each dot represents one square foot of vertical space as measured on the wall behind the desk, which moves closer to or farther from the window.

Thermal comfort zone on a San Francisco winter's day next to a clear plate glass window requires almost a six-foot setback.

In the first image, you see the “baseline” – clear glass. Right next to the window (indicated in cross section on the right), are almost 6 linear feet of unusable wall space. The blue and green color indicates “too cold” and “much too cold”. In this particular building, that’s a total of 26,000 SF going to waste!

A medium performing curtain wall reduces the arctic zone by half. Now only three feet of wall space is wasted.

In the second image, the desk has moved three feet to the right; and by the last image, showing the best curtain-wall option, total space victory is achieved.

With a better-performing curtain wall, the desk can go flush against the window, with no wasted floor space.

The most interesting thing about this graphic was that it wasn’t self-evident to present the data in this manner – but, once created, these illustrations are immediately convincing, even for non-technical people, of the value of thermal comfort. The study examined a number of other factors, including the feasibility using a perimeter heating system in the winter – but the impact of radiant temperature on thermal comfort remains the same.

Why Not Just Freeze Your Workforce in the Winter?

I have to ask this question, because it’s been the de facto answer for all the years that I was actually an office worker. What’s wrong with treating office workers like the commodities that they are, and letting them suck it up and deal? Why coddle them with expensive thermally insulated windows when cheaper glass will do? Well, aside from the fact that it sounds really bad to say it this way, it’s a poor idea to ignore conditions that promote ill-health. Even mild illnesses can cause absenteeism, or worse. People who can’t afford to stay home will continue to come to work – and less efficiently, too – while sick, thus spreading illness, reducing their own productivity, and prolonging their own recovery time.

Desirable office wear for poorly conditioned buildings can present the wrong image at the annual board meeting.

A 2003 report on sustainable building for one particular facility cites productivity increases of 5 percent and absentee decreases of 40 percent after moving into a renovated facility. [1] Other site-specific studies also cite increased productivity, reduced absenteeism, improved recruitment, and reduced turnover resulting from improved workplace environments. One might add that this would be particularly important for public agencies that don’t always pay competitive salaries, and who can no longer offset lower salaries by guarantees of job security.

How Do you “Measure” Comfort, Anyway?

I’m going to shamelessly plagiarize a summary from an article titled “Window Comfort and Energy Codes” [2] because I can’t say it any better than the writer himself – Jim Larsen of Cardinal Glass. He’s citing ASHRAE Standard 55, Thermal Environmental Conditions for Human Occupancy:

“Comfort can be evaluated with a statistical index called predicted percent dissatisfied (PPD). The calculation of PPD requires a knowledge of room conditions (air temperature, air velocity, humidity, and mean radiant temperature), and the occupant conditions (clothing level and metabolic rate). When comparing two conditions, a lower PPD is desirable as this reduces the risk of occupant discomfort.

Some common examples where cold weather PPD will be improved (lower):

• Increase thermostat setting;
• Adding layers of clothing; and
• Increase level of physical activity.

During hot weather the converse of these will improve comfort as well as increasing air movement and/or reducing humidity.”

(Note: ASHRAE Standard 55-2004, Thermal Environmental Conditions for Human Occupancy, is not a free download. Here’s one place that you can purchase it.)

How Hot Is Really Too Hot?

So far we’ve discussed thermal comfort and warmth, but of course in some climates cooling is a much greater concern, and even modern urbanites are questioning whether we really need it to be 65 degrees inside in the summertime, when that means a 40-degree differential with the outdoors. After all, humans have survived for millions of years without air conditioning, and complaining about the weather at least gave people something safe to talk about.

It turns out that yes, humidity and air movement have a lot to do with how overheated we feel, and a study I can’t locate at the moment was cited showing that subjects in a blind trial were able to perceive 92 degrees as comfortable – as long as there was sufficient air movement.

Stone lattices were a pre-industrial solution for desert climates that filtered incoming light while allowing air movement - although, making it dark enough to be comfortable might be too dark for most types of "productive" office work.

Maybe We’re Just Spoiled Here In America

This is another topic unto itself, but yes, cultural expectations can affect perceptions of “comfort”. However, those same cultural expectations that might induce one to tolerate greater extremes might also be more forgiving of seasonal and even diurnal fluctuations in productivity – AKA the afternoon siesta. Could siestas save the planet? Well… it’s probably an easier sell than telling everyone to just tough it out.

[1] Kats, G., Alevantis, L, Berman, A. et al. “The Costs and Financial Benefits of Green Buildings. A Report to California’s Sustainable Building Task Force”, October 2003, cited in “Occupant Thermal Comfort and Curtain Wall Selection” by Susan Ubbelohde, in the Journal of Building Enclosure Design, Summer 2006, pp 32-34.

[2] “Window Comfort & Energy Codes”, by Jim Larsen,  in the Journal of Building Enclosure Design, Summer 2006, pp 37-38.

With the solar industry booming, manufacturers and installers are racing to improve their products in every conceivable way: more efficient PVs; better inverter technologies; remote control, sensing, and automation; better energy-use reporting; smarter appliances; open systems integration; and a proliferation of grid-tied and off-grid configurations. One area that hasn’t gotten quite as much attention is the installation, which takes special training, and can be as much as 30-50% of the cost of the system.

Bay Area startup Armageddon Energy has a new angle with a patented product that GreenTech Media has dubbed “The Ikea of Solar”. The SolarClover snaps together in cute little 3-panel modules, each with its own inverter. Lightweight and easy to handle, these modules can fit “almost anywhere” as they say. That includes small areas of roof, or uneven roofs that wouldn’t accommodate larger arrays. Three of them (9 leaves), make a 1-kW system that’s enough to power most major appliances for an efficient household.

Dmitry Dimov and Mark Goldman, the founders of Armageddon Energy, helped us out with a few questions.

What is the SolarClover?

Dmitry: With the SolarClover, we tried to design an attractive, easy to install, affordable solar energy system. It features lightweight, high-efficiency hexagonal solar panels and a triangular rack that assembles in minutes. On the one hand, it gives consumers a fresh look and an affordable package; on the other hand, it is designed to be installed by contractors and tradesmen using the tools and training they already possess.

The SolarClover assembles as easily as Ikea's prefab furniture. The triangular frame snaps together at the corners and then is screw mounted to the installation surface. Each panel snaps onto the top and then clicks into place. Rounded corners make the assembly more comfortable to handle.

(To see it in action, visit the GreenTech Media’s documentary clip)

What’s so different about your product?

Dmitry: We use standard high-efficiency solar cells, the kind you find in traditional rectangular solar modules, but we replaced the glass topsheet with a high-tech polymer film (Tefzel, the polymer they used to create the Beijing Swim Cube) and added a lightweight rigid backpanel, which greatly reduces weight and allows us to easily create our hexagonal shape.

There are a couple of simplified solar assembly kits out there, but our configuration is uniquely attractive and easy to assemble – and we have been recently granted a design patent for it.

Is it true that any fool can stick it together?

Mark: We actually prefer that the do-it-yourselfers leave this one to the professional installers – climbing on a roof is not the safest thing you can do on a weekend – but the system does set up very quickly.  You can assemble the rack in literally a minute or two.  Finding rafters and attaching the system to a roof can be done very quickly by an experienced installer, as can running AC conduit to the service panel and performing the grid interconnection.

For comparison, a typical residential solar installation takes 3 men 3 to 5 days, for an average 5 to 7 kilowatt system.  Our system, which is 1 kilowatt AC, takes two men half a day.

What are the efficiencies compared to other solar products that are currently available?

Mark: We use high efficiency solar cells, such as Suniva’s new 19 % efficient cell, and the polymer films let slightly more light through than glass topsheets, so our efficiencies are better than most.

When can I get a SolarClover for my house?

Mark: Armageddon Energy expects the units to be commercially available by the end of this year.  The main question mark here is how quickly we get through UL testing, for those familiar with regulatory compliance.

Where did Armageddon Energy get its name? Are you preparing for the post-apocalypse?

Mark: We are preparing for the Apocalypse, which we believe will be sunny, beautiful and full of clean, fresh air.

[Editor's note: ROTFLMAO!]

How much does it cost? Your brochure says, “For the cost of a single high-end appliance” but let’s put that into perspective. A 1kW system will cover “all your major appliances” – let’s compare your product with a “typical” solar system including installation costs.

Mark: Our suggested retail pricing will be $8,500 installed for a 1 kW AC system consisting of three SolarClovers.  That puts us in line with the low side of installation costs for residential systems today, but at a much smaller scale – one need only purchase 1 kW instead of the 5 or 7 that’s usually necessary to get to that low cost per watt.

If any fool can install them, do you think renters could stick them on their roof and re-wire their appliances to use it, without even telling their landlord or PG&E? After all, rental property owners aren’t motivated to move to solar energy if their tenants are paying their own utility bills. And tenants aren’t going to shell out for an investment in someone else’s property unless they can take it with them when they leave.

Mark: More than tenants running wires to their circuit breakers, it’s more likely that property developers will add SolarClovers to their multi-tenant buildings and then simply recoup the cost like any other property improvement that allows them to command a higher rent – except now they’ll have a “green property” that they can promote.

And if being green doesn’t attract tenants, a small, peak-shaving system like this one will help insulate both landlords and tenants from painful utility bills in the summer [or painfully sudden utility rate increases, as occurred in 2001].  Whether it’s the landlord or the tenant paying for power, as the price of solar falls, you can bet that PVs will become a signal of lower utility bills – and ours will be right up there on the roof saying so.

While researching solar technologies, we at Green Compliance Plus heard from solar installers  who all seem to think that architects are hard to work with. So, we spoke with Fernando Valenzuela of Alter Systems in Berkeley about how to design a solar-ready home. Note that only about 5-10% of Alter Systems’ customers are owner/architect teams. Usually it’s the homeowners approaching them directly because they want to “go solar”.

So… why are architects hard to work with? “They have a groupthink… they like design, the look, but they don’t understand systems. They ask questions like ‘why can’t we use this roof’ without realizing that you can’t split up an array. Their projects aren’t always quick, either, and rebates that were designed for may be gone by the time the project gets through approval.”

Valenzuela went on to provide various design tips, as well as insights into new technologies, best-of-breed products, the difference between grid-tied and off-grid systems, costs and returns compared with conventional power, financing options, and the importance of grid parity.

Solar Design Tips for Architects

Consider building shape, roof planes, and orientation: With a remodel, people engage with an architect after the house is already built. It’s really best to take solar into account and design for it from the start. This may include choosing a lot or site that allows for a good solar orientation. Assuming that you do have some power to determine the shape of the building envelope, just make sure you include a nice un-shaded patch of south facing roof around 20 x 30 feet for your PV arrays. It goes without saying to consider proper solar orientation for the building, of course, if you have the option to do so.

Until recently, a single contiguous area was needed for solar arrays, and many products are still configured to work only if all the panels are installed together as a group. The panels should be tilted for maximum solar angle. Some panels lay flat and others can be tilted up; flat panels are aesthetically preferable and better for the neighbors’ attitudes.

Optimize roof tilt: The optimum tilt for the solar panels is your the latitude minus 15 degrees. In California, allow for a south or west facing planar area that is tilted around 20-22 degrees. Utility-scale projects and off-grid systems sometimes use solar tracking devices, but typically residential panels are mounted in a fixed position. The “solar window” is the maximum energy harvesting hours, between 9am and 3pm.

The sun's path across the sky changes according to season.

Assuming that you design includes panels that are built directly into the roof, your roof tilt will determine the panel tilt. “Not too steep, either, ” says Valenzuela. A 30 degree roof tilt is too steep – it’s much harder, and more dangerous, to install the panels. “It works your abs and butt!” laughed Valenzuela. And it’s not exactly “green design” when crews get injured, is it?

The roof tilt also depends on whether you have a grid-tied or an off-grid system, according to Valenzuela.

• Grid tied should be your latitude minus 15 degrees. Grid-tied systems are optimized for summer, because that’s when you’ll get the most energy out of the system, and thus you’ll get more money back at the end of each year.
• Off grid, on the other hand, should ideally be your latitude plus 15 degrees. For off-grid you maximize for winter, because you need the system working even in the worst-case scenarios so that you’re not left in the dark. Basically you want to make sure the system will produce in the winter months.

Allow space for conduits: If solar power is an afterthought, then you may have a visible exterior conduit, which can be less aesthetic than building it into the wall. If you put the conduit under the sheetrock it won’t even show on the outside. But even if you’re not installing solar today, you can accommodate future solar in the design.

Left, a typical retrofit requires routing the conduits wherever you can. Right, allowing a place for solar conduits that's built into the house allows flexibility for future solar.

Be careful with vent placement. “Don’t put vent pipes in the middle of a rooftop solar array. If the pipes stick up too far, they’ll get in the way of the PV panels.”

Make the roofing strong. Roofing should be 2 x 6 or 2 x 10 at 16″ on center for strength. Modern codes want 2 x 4 at 24″ across to conserve materials. If the span is too long, however, this doesn’t account for the weight of the people walking on it to do things like install solar panels. For this purpose, spans over 8 feet need thicker rafters. “We do a lot of retrofits,” says Valenzuela. “Old buildings in Berkeley for example are often 2 x 4 at 24 off center. For these, we may have to put in a brace.”

Keep basic sizing guidelines in mind. The amount of surface area you need for your PV panels depends on how effective the panels themselves are, and how much power the house requires. A rule of thumb might be 500-600 SF of roof (or other area) for the solar array to generate 5 – 7 kW. This covers a lot of places, even desert climates. “Even in the hotter parts of California, with heavy air-conditioning loads, it’s not too far off base,” according to Valenzuela.

Understand the racking systems. It’s good to understand how racking systems operate. “No roof penetrations” are needed. In the future, each panel may come with an independent energy panels with built-in inverters. Innovations include reduced installation time and cost.

Process

Choosing Your Solar Companies: A solar systems company is essentially a contractor/consultant who supplies, specifies, and installs systems. “If your client wants solar power for heating, cooling, electricity, or water heating, then you as the architect will need to establish a good relationship with a company that you can rely on to supply a well-designed system that is appropriate for the programmatic requirements of the home.”

“Try to work with a few solar systems companies that you know well, to get standard products and sizes for components. But don’t rely on just one company, because some companies are over-scheduled right now and orders are going unfulfilled.”

How Long Does It Take? Allow a month turnaround including all permits and paperwork such as rebates.

Customer Experience: So what happens when someone comes to you and says they’re ready to go solar? Here’s what your clients can expect.

1. Site evaluation. The solar consultant will most likely want to visit the house to inspect the roof area, shading, and electrical box. Some houses just aren’t suitable for solar. “Usually it’s a mounting problem,” says Valenzuela. A general rule of thumb for say a 1,200 – 2,000 SF house is to have flat or south facing roof around 20 x 30. Using micro-inverters helps reduce the amount of roof area that you need (read on for more information).
2. Proposal. Assuming the house will support a solar system, the owner gets a price proposal. “I have to ask why they’re doing it to figure out if it’s off-grid, grid-tied, or hybrid system. If they sign off, the paperwork starts.”
3. Permits and Rebates. Local permits for installing a solar system can take as little as a day or up to around 2 weeks depending on locale. The paperwork for tax rebate programs takes 2-3 weeks.
4. Installation. Alter Systems takes 2 days to install, but schedules for 4 days to allow for contingencies such as rain. The owners or occupants can continue to use the home and live in the home while the installation is ongoing.

Grid-Tied and Off-Grid Systems

One basic decision the owners must make is whether to tie their new solar arrays int the power grid. Grid-tied and off-grid systems are totally different animals in some important ways, but as solar power gains mainstream acceptance, it must also be able to integrate smoothly into mainstream infrastructures as well.

• Off-Grid systems are the classic “1.0″ of solar renewable energy. Although they tend to be associated in the U.S. with environmental activism, survivalist movements, and early-adopting technology buffs, they’re also essential in parts of the world where a centralized power infrastructure either doesn’t exist or isn’t reliable.
• Grid-Tied systems are mainly intended to reduce or eliminate energy bills, as in Net Zero homes. It’s a more mainstream market than either the early adopters or the green contingent. A main motivation is likely to be cost savings.

Although grid-tied systems are a newer concept, they are likely to be the wave of the future in industrialized countries. The components of a grid-tied solar system are the panel arrays, a power inverter to convert the direct current generated by the panels into the alternating current used by household appliances, a manual power disconnect, and of course the utility company’s usual infrastructure: the meter and switch box.

A grid-tied system is simple and straightforward. There is no need to store power onsite. Power generated is fed directly back into the grid, and home power needs are drawn also directly from the grid.

An off-grid system has more components, because of the onsite power storage requirement. In an off-grid system, the solar arrays feed into a combiner box which balances the inputs from each array. The combiner box combines or branches together the PV arrays/modules and then takes all the power through one set of leads to the charge controller. The controller makes sure your battery is charged correctly, and prevent over-charging.

The advantage to this type of off-grid configuration is the ease with which you can add supplemental power-generation systems such as microhydro or wind turbines. The goal of an off-grid system is to keep the batteries fully charged at all times. If there’s a grid tie-in, the battery won’t “sell” back to the grid unless it is already fully charged.

Which configuration you choose for your solar system depends on the reason why you’re going solar in the first place. Homeowners typically adopt a grid-tied system to save on energy bills, reduce their carbon footprint, and perhaps to show off to their neighbors. Valenzuela cites an estimate from the Journal of Assessors and Appraisers that for each dollar you can shave off your annual home operating costs, you add $20 to the property value.

According to Valenzuela, based on his experiences with his own customers, homeowners might choose off-grid because they’re in a remote area, and either it’s too expensive to bring the grid out there, or it exists but is not completely unreliable. “Some people do it because they hate public utility companies just on principle,” notes Valenzuela. “They’re also more likely to be DIY types who are comfortable assembling their own systems,” he adds.

An off-grid system includes an onsite storage battery. It's designed to be self-reliant. The homeowner can add a grid-tie option as shown above.

So what are the pros and cons of each type of solar configuration? Grid-tied systems require less equipment and employ simpler configurations; on the downside, they’re limited based on inverter sizes.

With off-grid systems, it’s easier to add supplemental renewable-energy systems on the side for things like wind or microhydro.

It's easier to add supplemental power generation systems to an off-grid system with its own battery storage.

Off-Grid for Villages: A typical residential home might need a 6kW system. For sites such as an army base, a remote ranger station, or a farm with multiple buildings, a system called AC coupling can deliver 20 kW or more. Basically it’s a way to create your own micro-utility company, and collect power from solar arrays on several buildings, using one central inverter (such as the Sunny Island off-grid inverter from SMA Solar Technology) and a central storage area. “This type of installation is very useful in places like the Caribbean, island countries or places without any infrastructure,” says Valenzuela.

Could you implement something like that in a city neighborhood, I wondered? A residential collective of some sort, for people who live in urban areas but still want to have totally independent self-generated power, and who want to pool their money to invest in economies of scale? “You’d have to do all your own wiring,” Valenzuela responded. “They’d have to be fairly close together.”

Well… with the geek factor in this area of the country, I wouldn’t be surprised if it’s already happening. After all, if a few homes drop off the grid on a single city block, how would we ever know?

Solar Grid Parity

I didn’t even know what this was, but with all the talk about the ROI of solar systems vs. fuel cells vs. high-efficiency but conventional systems, it’s a very important concept. Solar grid parity is a tipping point in the energy marketplace when the cost of energy production for solar power will be equal to or less than the cost of generating conventional, fossil fuel-based grid power.

A common comparison is dollars per watt or cost per kWh. U.S. average power prices for last year ranged from 5 – 15 cents per kWh, averaging roughly around 10-11% (businesses were 1 cent cheaper).

This number includes upfront investment in equipment although of course there’s debate over how to calculate it and when this momentous day will actually come. 2012 seems to be a common guess, although coincidentally that’s also the end of the world, according to the Mayan doomsday calendar).

Prediction: “a number of solar companies will hit a long-pursued industry target of $1 per watt by 2012.”  This “race towards $1 per watt” means that “within a few years solar panels will be able to generate electricity cheaper than the grid in many regions of the world.” (Sunnier regions have a bigger solar payoff, not surprisingly.)

Another claim is that we can reach 2012 grid parity in “almost half the US” and he also notes that there are several ways to calculate grid parity.

Even 4 years ago, solar was still pooh-poohed as a boutique technology for wealthy do-gooders or conspicuous consumers. But that was before tax rebates and stimulus dollars made it easier for new owners to “green” their homes. Other factors include improved component efficiency and a wider array of creative financing options such as these options from SunRun to purchase solar power as a service, to lease the equipment to the owner, or to help owners seek solar financing through local municipal programs.

So, is it a sure thing that in 2012 we’ll all be putting PG&E out of business? Doubtful, but there’s definitely a sense that price parity is coming, it’s just a matter of when. For example, higher interest rates could hurt financing, and if grid prices fall, parity won’t be reached nearly as soon. For those who prefer to focus on equipment efficiencies, there’s a rather geeky engineering article from BP Solar that discusses current and future efficiencies, including emerging new technologies such organic photovoltaics and nanocomposite solar cells.

The $1 per watt number is disputed as overly simplistic on one investor blog: “PV’s competiveness with the grid varies wildly based on the region… The idea that module prices need to come down to $1/W for solar to be competitive is misplaced at best” because “PV is already at or near parity with the grid in a number of markets”. This blog also includes a good discussion of calculating the cost of various types of conventional power, including nuclear.

Solar Financing Innovations

For homeowners who want to finance their solar installation, three good sources are:

• Tax rebates
• Municipal funding options through property taxes
• Bank loans

In the second case above, this is a plan being adopted in some localities such as Santa Rosa. Basically, the city obtains the funds for solar installations at a very low interest, say 3%. The city then loans it out to homeowners at a slightly higher but still reasonable rate, say 7%. The owner then pays back the loan in the form of an extra property tax surcharge every year. If the house is sold, the new owner is responsible for continuing those payments as part of the home’s property tax bill, and the new owner of course enjoys the reduced energy bills in the meantime.

“Some owners just pay for it with a credit card,” said Valenzuela. I can’t imagine plunking down $35-$60,000 on my card but then again, I can’t imagine watching the national average of television, either. “Every dollar decrease in operating cost adds an extra $20 in property value,” said Valenzuela, “but equity is fake money. So, we don’t include this increased equity on our cost/benefit analyses that we show customers in our proposals.”

New Solar Products

During the course of our conversation, Valenzuela mentioned some of his favorite new solar technologies. In no particular order, here they are.

Solar forced air heaters. These devices are installed on a south-facing wall or roof and are best used as a complement to other heating systems, a boost but not a replacement. They’re small and relatively efficient, at least compared to PVs. A single 8-foot panel is enough to heat a small room. They use no fuel and have no moving parts except a fan to draw cold air into the panel and push heated air out directly into the room. They don’t work as well on cloudy days, obviously. And you don’t even need fancy PVs or heat collectors: here are some ingenious DIY solar air heaters made from recycled aluminum cans.

This 8-foot solar wall air heater from ClearDome Solar in San Diego can heat up to 500 SF of residential space.

Micro-Inverters. Green Compliance Plus has mentioned the breakthrough of micro-inverters in a previous post – basically, by having separate inverters for every PV panel in a solar array, you can harvest more energy because shaded panels no longer bring down the performance of the entire array. One maker of micro-inverters is Enphase Energy. Valenzuela waxed almost poetic about Enphase products: “At the recent Green Building Expo, their booth was mobbed while the big players were empty!”

FLEXpower ONE Off-Grid Solution. Valenzuela made special mention of one particular product from OutBack Power called the FLEXpower ONE. He recommended this for total off-grid systems including smaller installations such as boats.

Xantrex XW Grid-Tied Solution. The Xantrex XW from Schneider Electric is recommended for homes that are grid-tied with a battery backup. “It’s not quite as flexible as the OutBack for very small installations, but it’s easier for designers, because it’s a high-quality product and you can scale it up,” says Valenzuela.

But what should architects really know? “Use Enphase!” says Valenzuela.

One of our Title 24 clients, Okamoto Saijo Architecture, recently completed a  $50M retrofit that included creating a 900-kW PV system that is currently one of the largest affordable-housing solar installations in the world. We interviewed one of the principal architects, Eric Saijo, about how the Crescent Park project went from his perspective. He was actually quite happy with the outcome, and after 4+ years of budgeting, negotiating with utilities, the project is completed.

Crescent Park, an affordable-housing solar retrofit by Okamoto Saijo Architecture.

How were you selected?

In the last 12 years we’ve done lots of affordable housing rehabilitation projects. In this day and age people get put into certain categories. We’ve developed a reputation.

Eric Saijo and Paul Okamoto of Okamoto Saijo Architecture, at one of their own project sites

It’s less glamorous, but that’s OK. This client had been working with another architect and the project got put on the back burner for half a year. In 2005, they came to us. We spent 2 years in design and documentation to figure out the project scope.

How was scope determined?

Identifying the budget is always a challenge. They had a wish list of many items, including PV for 100% of electrical needs. We did feasibility studies to analyze whether they had the budget for all the things they wanted to do: update kitchens, flooring, waterproofing. The solar portion was only one aspect.

You did a lot of analysis in addition to design.

We worked hand in hand with our contractor (Brandon Slater of West Coast Contractors) from Day 1 on pricing and budget.

What would you do differently next time?

A better question might be what have we learned? Let’s talk about this instead. We learned more about handling the specific challenges of pulling off a PV installation in a 40-year-old multi-building complex.

Okamoto Saijo Architecture has done "green" private residences as well as sustainable public housing.

We started off with plans for 100% of onsite electrical needs generated by PVs. Our solar engineer did a layout showing where we could put panels on all roofs, taking tilt and orientation into account for each building. We also had an idea of the number of kWh that we needed to generate. Then we could look at all the other constraints.

What were the other constraints?

Not enough roof area on the existing buildings, and existing building systems that were not designed for the structural loads of the panels and the installation process.

Are solar panels really that heavy?

No, but retrofitting existing buildings triggers all sorts of re-analyses, and one of these is to re-analyze for seismic load. Any building that’s 40 years old won’t pass today’s seismic code requirements. And any increase in load over 5% triggers this seismic analysis… it’s a huge limiting factor.

Most PVs get installed in a design-build fashion.

When installing panels, there should be no live load on the roof where the panels are… adding even a minuscule amount of weight can be a problem sometimes.

What was the problem with retrofitting to use existing equipment?

How to make the most of the existing electrical service equipment in a retrofit! The simplest thing to do for an individual building is to install a large PV system and replace all the service equipment and tie in the PV to the entrance panel breaker.

Connecting those beautiful photovoltaics to the public utility's metering and grid system can be a "non-trivial exercise".

The electrical code is written in such a way that PVs are considered a “load” meaning that you might have to up-size the service equipment. The secondary field lines from PG&E, with extra runs to each building, for 24 buildings on 6 acres… this becomes a huge cost.

However, the electrical code does allow for line-side tap between the meter and the main shutoff switch. The equipment is now 40 years old which the code still allows, but it is physically difficult to implement line-side taps. We had to persuade PG&E and the head building official to conceptually approve it.

The larger buildings had enough space in their service equipment to clamp onto existing conductors when we needed to do that. We had to modify the charge condition meter main shut off and route it through a new gutter. We could do new tap here. and then clamp to conductor.

UL certification was another issue. The existing equipment, being 40 years old, wasn’t UL fabricated. Small enough to service meter and switch board were separate pieces of equipment. When the contractor, the electrical building inspector, the electrician, and the solar engineer got together – it was a tense moment!

When architects and building inspectors meet…

The next challenge was getting our systems approved by PG&E. You have to get approval from your local utility in order to submit for solar tax rebates. A 900 kW system like this one must undergo review at PG&E’s engineering department. They analyze their own infrastructure, including their transformers and underground conduits. In this case, PG&E’s equipment was also 40 years old, and perhaps built to prior standards. It took them quite awhile to analyze our proposal.

At first, they rejected it and wanted us to pay to upgrade all the transformers serving the complex. This was due to a loophole in the agreement for rebate systems for PVs, which allow the utilities to charge the client for these upgrades.

But if the power is generated onsite, why do you need those transformers?

In the middle of the day in a residential complex, power will be flowing out towards the grid. Changes to the photovoltaic systems had to be calibrated on the utilties’ side as well as ours. They had to change their meters so they could spin backwards.

Is that a smart meter?

No. A smart meter is one which is read remotely. [Communication is essentially what makes a smart meter more intelligent than a dumb meter]

Does PG&E do enough to support people like you?

There are people in various departments who did. The engineers really got behind us and worked with us to MAKE it work. Then there are other departments. All of them get delayed for a number of months without clear explanation. It could just be under-staffing.

Here’s an example of the type of problem we had to solve together with PG&E engineering… in one area of our project, there were 5 buildings served by one transformer. At first the told us that we had to pay for a new transformer, as well as pay for new primary and secondary feed lines – this would cost $200K.

Naturally our client wasn’t happy. PG&E countered that they were concerned that the kW would bump up the voltage above what they’re legally required to keep it under. Then they said, “But.. if you set the trip point on the inverters down, then we’ll approve.”

Inverters are normally set to 132V and they wanted us to set them at 127V. The PG&E grid is 120-122V but it just happens to be high in this particular location. As we installed systems in those 5 buildings, the inverters started to trip off. We’re still negotiating with PG&E over what to do.

What would you do different?

I wouldn’t accept a trip point! It was a sign that PG&E has real concerns about its own systems, that they were worried about the potential for voltage to increase too high . Our solar engineer had never run into that before. It was a real learning experience!

Even a genius can have a learning experience.

At this stage, our client didn’t know yet how much financing they could get. The budget was still in flux, and they really weren’t willing to accept sudden new costs. Especially in large renovations, you have to hold a large contingency fund; with our project, those funds are now available for post-construction.

What do the residents think about it?

Affordable housing is a very complex thing in our society. These are extremely low-income people. I didn’t have much contact with them but my sense is that they are appreciative of the renovations that included window replacement and other building improvements which improved their comfort and quality of life.

Another affordable housing project from Okamoto Saijo Architecture, PositiveMATCH is an adaptive re-use of a historic building in San Francisco, serving women with HIV and their children.

The buildings were made more airtight, with better insulation, new windows. And… cleaning the duct work after 40 years most likely improved the air quality.

Drainage for the entire site was improved. It’s very close to the Bay, with a high water table, so flooding is a concern. The storm drains were constantly backed up prior to the renovation, and ground floor units had water infiltration. All of these measures made the units more comfortable.

Another private residential design from Okamoto Saijo Architecture, a passive-solar farmhouse in Napa, CA

We also worked with the client to improve the visual appearance of the buildings. New paint schemes, and individual colors for each building. Before that, all 26 buildings on 24 acres had been colored the same. How monotonous!

Of course the resident’s don’t pay their own electric bill. That’s usually the thrilling part for homeowners is seeing their utility bill reduced. In this case, our client financed the PVs because they also pay the utilities.

Financing was through bonds. Our client was not the original developer. The project was originally built by a market-rate developer together with HUD. Our client bought it later, around 20 years ago.

Many of our Title 24 clients have been asking us whether they can safely specify LED fixtures that would qualify as “high efficacy” lighting under Title 24. Could one conceivably create an entire lighting plan for a custom home using mainly LEDs, and if so, would it pass Title 24? Would it look any different to the untrained eye? Would it actually use less energy? Or, are LEDs better used as a supporting component in a diversified lighting plan rather than as the main workhorse? Are LEDs sustainable to manufacture? Do they use less power in a real-life installation, not just in the lab?

The answer to LEDs in California is a qualified but definite yes. There are definitely products out there that will comply with California’s energy codes, and we should see more coming to market this coming year. The issue is not the LED lamp itself, but the housing, because the fixture’s efficacy depends on the entire assembly.

As a designer, there’s some fine print to watch out for. To say a product “complies” with Title 24’s high-efficacy standards involves certification and documentation. There are many more products that would comply, but they’re made by smaller local manufacturers who can’t always afford the lengthy and expensive certification process. These demi-compliant products can be sold to retail consumers as after-market products, but without certification they wouldn’t pass a formal, by-the-book inspection. Manufacturers of lighting fixtures can test their own products of course, but to get a product certified means paying for an outside lab to test the products, and of course re-certification every time the code changes.

On the plus side, many building inspectors are favorably disposed towards LEDs and are willing to consider the products themselves on a case-by-case basis, as long as the product data is credibly presented. One of the lighting designers we spoke with, Henry Chu of Halogens Inc in Millbrae, CA, makes his own LED fixtures and is currently presenting some of his new products to local building officials for their feedback.

LED chandelier designed by Kenzan Tsutakawa-Chinn

High Efficacy Definitions

Title 24 has various requirements and incentives to encourage the use of high efficacy lighting as measured by the amount of visible light emitted per watt of power consumed. The required threshold varies according to the number of watts in the luminaire, as distinguished from the lamp (bulb) itself. 

Most people associate LEDs with the lamp component only, because they’re used to seeing them used singly as indicator lights on machinery. A luminaire is the entire assembed fixture, including lamp, ballast, housing, and connectors. Only luminaires can be high efficacy. It’s really the luminaire, or the entire fixture, that determines the efficacy – the bulb by itself is not enough.

• Under 15 watts, must have an efficacy of 40 lumens/watt
• Between 15-40 watts, must have an efficacy of 50 lumens/watt
• Over 40 watts, must have an efficacy of 60 lumens/watt

Three LED lighting designs from Litefuzion.com. Designs by Iestyn Davies and Jack Wimperis.

This prototype fixture uses LEDs and fiber optics.

LEDs can be used as color accents in room designs without turning the place into a disco. This image from Litefuzion.com; design by Jack Wimperis.

“LED lighting still has a long way to go,” says Hiram Banks, a San Francisco lighting designer recently profiled on our sister blog, The Architect’s Take. Product unknowns include optimal operating conditions and product life. “Most data we have is hypothetical based on lab studies. There are not many long-term studies because it has not been around long enough. So, when scientists and manufacturers say that white LED lighting has a lifespan of over 40 years, they are saying that with hypothetical data from the lab. There are many factors that determine the life of the LED light source, and they are becoming more evident as LED installations start to age. For example we have just learned that LED lighting needs a lot of air circulation and does not like heat, which can kill it in less than a year!  We do not know if over time the light output starts to diminish as in most other light sources, or if the color starts to change.”

Color accents work in bars, too, although I feel like I'm about to get on a Virgin Atlantic flight. This one also from Litefuzion.com

This customer service center by Future Group Lighting Design integrates color-changing LEDs with conventional lighting. The stripes change color depending on the time of day, with warmer tones in the morning and bluish tones in the evening.

There are three ways to make white light using LEDs:

This fully programmable LED array was created by 3 Way Labs in Menlo Park, CA. I've seen their work in person and I was amazed at the programmatic controls of color, light level, and the patterns as well - surprisingly organic and natural in flow.

Sprinter S Light shower enclosure by Sprinz, a German company

This LED installation was designed by Leo Villareal at the National Gallery of Arts. Photo: Min Batsone

Links for Further Study

• Interesting page from Light Emitting Diodes.org, all sorts of wavelength data for LED white light sources.
• Excerpts from a Californa Energy Commission PDF slide show: Title 24 2008 Changes to Residential Lighting Standards
• 3 Way Labs, maker of the “Cubatron” series of programmable displays
• Litefuzion, a UK-based company doing interesting LED lighting designed fixtures
• Case study from Future Group Lighting Design, also in the UK

After January 1, 2010, all new homes in CA must include whole-house ventilation systems. Yes… we’ve made building envelopes so efficient, that now we have to in essence introduce highly controlled leakage. There are two mandatory ventilation features in the new Title 24: 

A good ventilation system will filter out indoor air pollutants (VOCs like formaldehyde from particleboard or acetone nail polish remover) as well as filtering outdoor air on the intake side; however, not all whole-house ventilation systems include outdoor air filtering. Here’s a summary of the ventilation course module from last week’s Title 24 update class. 

Moisture Control

Exhaust fans, which were common enough before, now required in all kitchens and bathrooms. Really, any “wet” room like a laundry room that has plumbing, should have an exhaust fan. One of the side effects of tighter building envelopes has been increased concentrations of mold in the indoor air, and keeping moisture down helps prevent the growth of mold. 

Single-room exhaust fans can be intermittent (operating only when when occupied) or continuous with an override switch. They must meet minimum rated capacities for cubic feet per minute (cfm) or air changes per hour (AC/h) and be ducted to the outdoors. Look for exhaust fans with Energy Star ratings for low noise level and high efficacy.

You may need to educate the owner on how to use these fans, but unfortunately my notes trail off at this point. Required sizing for exhaust  fans was roughly 1 cfm/SF, in 50-cfm increments, so a typical range might be 50-300 cfm based on the number of showers, hot tubs, toilets, etc.

Whole House Ventilation

The motto is “build tight, ventilate right.” The reason is that a tight home costs less for conditioning and ventilation combined than a leaky home does for conditioning alone. 

Ideally, the indoor air pressure should remain balanced. A really effective whole-house ventilation system includes both intake and exhaust, in equal amounts, running all the time. Intake is filtered, from a controllable location. They can include heat-exchange features too. However, these balanced ventilation systems are harder to install, and are, in the words of the presenter, “susceptible to insulation neglect.” 

A balanced ventilation system includes supply and exhaust. Images from www.energysavers.gov.

In California’ relatively dry Mediterranean climate, supply-only ventilation is OK. In very cold climates, a positive indoor pressure can lead to moisture buildup inside the walls as moisture-laden warm air is forced outward through the walls until it meets with cold air and condenses. Advantages include filtering of outdoor air, and better delivery of air where it’s needed – including bedrooms behind closed doors. The presenter noted that they can range widely in energy-efficiency, but didn’t explain why.

Supply ventilation creates a positive indoor air pressure.

When using forced-air fans for continuous ventilation in a supply-only system, it was recommended NOT to use a typical forced-air fan, but instead to use either a variable-speed forced-air fan or a supply fan that is separate from the forced-air system itself. 

An exhaust-only ventilation system is cheaper, but brings in unfiltered air, draws in other outdoor pollutants, and air distribution is easily disrupted by closed doors. Exhaust-only systems are not good with tight homes and open fireplaces, either – the negative indoor pressure can actually draws smoke from the fireplace or carbon monoxide from the furnace back into the house.

Exhaust-only ventilation creates negative indoor air pressure that relies on infiltration rather than an intake fan.

To size the system, multiply the cubic volume of the conditioned space by the number of air changes per hour. Although the code minimum for air changes is 0.35 an hour, the presenter noted that most international standards are higher: 0.5 or even 1 AC/h, and some exhaust systems seem to specify a much higher number. 

Whole-house ventilation system sizing formula

For example, a 2,000 SF house with 10 foot ceilings would have a cubic volume of 20,000 ft3. (Note the conversion of hours to minutes.)

The recommended best practice is to take the cubic feet of conditioned space times the number of air changes per hour, and then convert that to minutes in order to get the cubic feet per minute (cfm) of the house ventilation system.

Ventilation Energy Efficacy

Although there was a lot of discussion on this topic, the summary slide says to pay attention to the cfm/W – that’s the cubic feet per minute of air moved, per watt consumed. A lot of the efficiencies seem to be dependent upon how well the system is sized, designed and installed, and how well it’s suited for the particular home and climate. 

A well-designed continuous mechanical ventilation system should consume the power equivalent of a single 20W bulb running in the background 24-7-365.

This past Monday, I went to an all-day Title 24 class with CABEC and didn’t fall asleep once! There were a few eye-openers  worth sharing, since we’ve already been trumpeting the endless “Change is coming!” for months. 

Title 24 has grown from a minor paperwork requirement into a PROCESS, with more forms, more steps, and more people involved. Bifurcating bureaucracy… what a surprise!

The intention is that all Title 24 projects that require HERS field verifications - which could be most of them - will be tracked in a centralized database throughout the life of the project, and there is more oversight to check that the field verification and installation certificates match the original CF-1R report.

The Cliff Notes version is roughly:

• Title 24 documentation will become more expensive to do.
• And take four times as long.
• It will be harder to get your projects to pass.
• You’ll have more people to coordinate.
• Massive confusion first 6 months.

But the kicker? All of this depends entirely on how it’s enforced by local building departments.  

So, what should design professionals be doing over the next 6 months? 

Submit any upcoming projects before January 1 if you can.

Clients

Next, prepare your clients. They should expect that after January 1, the Title 24 process will become noticeably longer and it will be harder to meet the standards. The impact on the building may be substantial. Owners must choose their contractors wisely, because there is more onus on the builder now to cooperate with the Title 24 process all the way through the project. 

This in turn will make it more challenging to make changes after certain decisions are made, particularly to core systems or overall sustainability goals. In addition, owners must plan ahead to qualify for the various  incentives that are still available.

Builders

As a designer, you may need to educate the builder as well. The general contractor has a lot more forms to fill out now, including what used to be the old kitchen lighting form. Actions taken by the builder can end up having more of an impact, because the new Title 24 has an increasing emphasis on inspection, rather than simply relying on claims made on the initial proposed energy calculations. This means the builder needs to be conversant with Title 24, so they understand how their actions can have an impact on the process. 

For example, there’s a credit for attic venting, i.e., using more vents and placing them in the proper spots. Either the architect needs to detail it exactly, or otherwise communicate to the builder that a compliance credit is being claimed for one or more of those building features. Builders must know the implications of field substitutions for things like roof shingles. The expanded credits for Cool Roofs means that only roofing products labeled as certified by the Cool Roof Rating Council are allowed. Since many manufacturers are now making Cool and non-cool versions of the same product, it’s extremely important to stick with certified products if a Cool Roof compliance credit is claimed.

In general, there is an increased need for coordination among the project team: designers, energy consultants, builder, subs, HERS raters, and other special inspectors all have to be apprised of changes. even those made very far down the road. 

Designers

Finally, prepare yourself to design for the 2008 standards in 2010.

• Certain decisions must be made much earlier, at permit stages (heating, ventilation, windows, roof)
• Architect must specify everything a lot sooner down to the product detail level.
• Pay more attention to specifying only products approved or certified (rated windows, cool roofs, fire-rated products where required)
• Provide a lighting plan showing wattages and low/high efficacy fixtures for the builder so that project is built and lighting is documented as intended
• Pay more attention to efficient design for ductwork, pipes, and ventilation.
• Field substitutions will be more cumbersome, and may trigger another round of reporting if the new product labeling has different energy performance ratings than the old one. 
• More reports to process
• It’ll be a lot harder to use metal framed windows and it’ll be harder to source them.
• Don’t treat the building’s energy performance as an afterthought. The day before a big permit submittal is not the time to find out that the house will need major system changes in order to pass.

What did people care about in the class?

Everyone asked over and over again about the new registration process. The upside is, we think it’ll work fine, but no one’s been able to test the process end to end yet.

No you don’t need to register every single project with a HERS provider – unless the project requires onsite HERS inspection. Progressively stricter energy codes will most likely require more verifications – it’s possible that most or all of the Title 24 projects that come through Green Compliance Plus will trigger one HERS inspection or another.

We spent considerable time in class on the whole-house ventilation requirement. A ventilation systems expert explained in great detail the different types of ventilation systems available and which ones were preferable. I’ll write a separate post on some of that information, very worthwhile.

Lighting requirements weren’t that different but LEDs have a place now, and there’s a way to “buy” additional incandescent watts for the kitchen by adding extra dimming and vacancy sensor controls. Which you already need to have anyway. Internal kitchen cabinet lighting is exempted. The old kitchen lighting form is gone, and is now part of the builder’s CF-6R form. (Another update on LEDs coming soon)

Some considerations apply only to production homes. There are details about HERS sampling and other such items, very relevant to builders and developers.

Everyone will have to pay close and constant attention to local green building ordinances, which may require exceeding Title 24. But then again, so do many incentive programs, so you might as well design for that 15% over. Local green building ordinances are NOT legally enforceable until they have been approved by the CEC. 

There were some interesting possibilities in Marin County, which seem aimed at discouraging the construction of larger homes unless those homes are super-efficient. As far as I know, none of this has been enacted, but it’s under discussion. If all 12 Marin jurisdictions buy into this, then these would be in force throughout Marin County. 

• Homes over 2,500 SF have to beat Title 24 by 15%
• Homes over 5,000 SF have to beat Title 24 by 30%
• Homes over 7,000 SF must be Net Zero Energy

Renewable energy companies must be doing well these days. Between green stimulus dollars, soaring energy costs, recession-weary homeowners, and increasing public demand for clean energy, it seems like homeowners would be queueing up for the next Net Zero Energy conversion. And those who can afford the initial outlay probably are. But what about the rest of us who don’t have $35,000 just lying around?

We spoke with Kent Halliburton of RealGoods Solar about the state of the art in solar technologies, focusing on products that are available today. “Here’s a stat for you,” he said. “At a recent solar symposium, it was said that 92% of customers want solar energy but 88% don’t know how to get it.”

Hmm… well, if I wanted a new furnace, I’d look in the papers for contractors who installed the type of system I wanted. So what’s stopping these people from typing “solar installers” into their favorite online search engine?

Maybe what he meant was they don’t know how to PAY for it. And until now, there weren’t good financing agreements that allowed people to pay as you go. “People talk about solar price points as if it were a deterrent,” Kent said. “People aren’t as upset about the price point for vehicles like a Toyota or a Chevy, because car dealers sell in terms of monthly payments, not total system cost.”

Solar as a Service

“We have a new financial product offering solar as a service,” he explained. Instead of having to purchase their own solar system, the homeowner contracts to have the system installed and maintained by a third party – in this case, Sun Run, our financial partner. The equipment is actually owned by Sun Run and is sized to meet about 80% of the home’s total projected energy needs. The other 20% is purchased as conventional power.”

In the arrangement described by Halliburton, a homeowner signs an agreement through Sun Run to purchase from Sun Run all the power generated by the solar system, locking in a fixed rate for the next 18 years. The homeowner also pays a certain amount down, anywhere from $0 to around $2,000. This pricing is a little different from the more familiar metered pay-for-what-you-use model, since the homeowner commits to purchasing ALL power generated by their solar system system, whether or not they use it. (Unused power is usually fed back into the power grid.)

System output is somewhat variable depending on the weather, and is usually estimated over a year’s time to average out seasonal ups and downs. The systems come with site-specific production guarantees. In any given month, the homeowner might under-produce and end up using a small amount of conventional power – but in the following month, a span of sunny days might generate a solar surplus that would then act to reduce the amount of kWh billed by PG&E at the end of the year.

A More Efficient Home Needs a Smaller Solar Array

Since the homeowners are already committed to paying for the output, the thinking is to size the system a little on the small side so they use up what they’ve already paid for. A conservatively sized system also encourages homeowner to reduce energy consumption. “For every dollar you save on energy efficiency, you can save $3-$5 on your solar system.”

Additionally, PG&E’s tiered rating structure means it’s cheaper to buy power from them at the lowest tiers – but not at the upper ones. And if the system produces more than they need, they’ve already paid for that portion of the power and it’s still overall cheaper than PG&E rates.

“But don’t wait to energy-proof your home first and then get a solar system, because it’ll take you months and during that time you’ll still be paying for conventional power. We encourage people to do everything possible to their home while installing the solar system.”

Latest Solar Technologies

So what’s the state of the art in solar technology? According to Halliburton, there remain two main technologies: silicon-based panels, and thin film panels. The tradeoffs are cost and efficiency – thin film is cheaper but less efficient, so you need more of it, and more roof space, to generate the same amount of power. So, what’s the best money can buy as of today?

• Silicon-based panels currently cost around $2.25/watt and are around 16% efficiency. That means that 16% of the sun’s rays that actually fall on that panel are converted to usable electric power.
• Thin-film panels are around $1.50/watt and around 8% efficiency.

[Note: These prices quoted by Halliburton are for the panels, not total installed system cost. On Sun Run's site the price is listed as closer to $8/watt.]

Large commercial applications can afford the space for huge arrays, but thin-film solar products can be flexible and more adaptable to portable off-grid field shelters.

What’s the most efficient, top-of-the-line system that’s available today? “SunPower and Sanyo both make products that are around $1 per watt more expensive than average. They’re around 17.5% or 18% efficient. You have to watch it though, because some manufacturers use a measure that is per cell, not panel efficiency. By contrast a so-called middle-tier ‘average’ system might be more like 14.5% to 15% efficient.” Today’s thin-film solar products top out around 9% efficiency.

“Silicon-based panels are better for residential and small commercial applications,” said Halliburton. Larger commercial applications have the real estate to install larger arrays of thin-film panels, but smaller buildings might need a smaller footprint and thus a more compact and efficient system is better, even if the initial costs are higher. “The most common choice is definitely the middle tier.”

Solar Inverters: The Hidden Factor

But even more important than the panels themselves are the inverters, and that’s something most people never think about. An inverter is necessary in order to convert the DC power produced by the solar panel into the AC power that’s used in a home. In the past few years, advances in inverter technologies and configurations have further improved the potential yield from an otherwise average solar array.

Halliburton described how inverters function. “The emergence of micro-inverters has done more to change the solar landscape even than the incremental gains in efficiency that we’ve seen over the years. In the older systems, there was one inverter for all the panels, but with a micro-inverter, you can have one inverter for each panel.”

To get an idea of why this is so important, consider a 4 x 4 solar array of 16 panels on a roof that is partially shaded at certain times of day. If even one of those panels is shaded, then its output is reduced – and the inverter can only gather the output from all the panels at the lowest common denominator. “With a single inverter, the weakest link brings down production for the entire array.”

With a single inverter, the two shaded panels will bring down the performance of the entire array during the time that they do not receive full sun.

By contrast, an array with micro-inverters is less sensitive to partial shading. I observed that this sort of thing must be a no-brainer for an engineer who already knew how the inverters worked with solar arrays.

With separate inverters, each panel is always producing the maximum possible based on the available light that reaches its surface.

Looking Ahead

What’s the state of the art now as compared to 5 years back? “Gains are incremental year by year,” said Halliburton. “For example, 5 years ago we had a 168-watt product from Sharp. That same product today is 198 watts. We try to avoid the ‘Apple syndrome’ where users hold off on buying a new computer because they’re always waiting for next year’s model.”

Halliburton stressed that homeowners didn’t need to wait to install a solar system, even if they were also planning other home improvements to increase building efficiency. Although they might think that a more efficient building with all the latest energy-scrimping appliances will need a smaller solar array, the systems are already sized with this possibility in mind, and in the meantime, why should the homeowner continue to throw away money on the electric bill for all the months it’ll take to complete their energy remodel?

Where do you see solar technologies 5 years from now? “It’ll become more ubiquitous, and continue to make incremental gains. I don’t see any silver bullets, meaning a brand new technology that’s disruptive in the market. In fact, I think the real change is going to be in education. People judge energy consumption based on the number of switches that they flip. They don’t understand what they can’t see. Customers will need to educate themselves and become more conscious of their consumption habits.”

What About Renters?

What’s really stopping people from buying solar systems? Well, not owning your own home is one barrier, although an arrangement called Virtual Net Metering can allow someone who lives and rents in one area but owns property in another town to install a solar system on the property that they own, and have the power it produces be counted towards the energy bills for their rental unit elsewhere. 

The Solar Homeowner Experience

What’s the solar homeowner experience? Do they notice any difference, or do they need to do different sorts of maintenance? Do they ever run short of power? Does the homeowner get an energy bill every month like the rest of us? 

“Other than washing the dust off the panels every so often to improve their performance, not much. They still get monthly statements. There’s online monitoring and automatic billing. The inverters might need to be replaced sometime between years 12 and 17; the panels themselves are guaranteed to produce up to 80% of their original efficiency even after 25 years.”

Visibility into System Stats

How much visibility do homeowners have into how well their system is doing? “The inverters tell them how much power their system is producing, and with online monitoring, they can see all the stats easily.” 

What about whether their panels are really operating at maximum efficiency? “Most customer don’t care about that level of detail, but one could install sensors to measure solar irradiance levels if someone really wanted to know that.”  What they typically get is a quote on what their system will produce on a monthly basis. 

The early adopters were more likely to be gearheads and DIY types with the engineering skills to really prove and verify their own systems. As solar power gains wider acceptance, people are more willing to trust it the way they would with a new conventional furnace unit.

Financing the Future

The impression I had after speaking with Halliburton, especially about the Solar as a Service arrangement, is that innovations in pricing structures and financial incentives will be as challenging – and as necessary – as any engineering improvements to the products themselves. RealGoods has been around for 31 years, in fact RealGoods sold the first solar panel in the U.S. back in 1978. They’ve installed over 5,000 systems to date, with around 200 customers signed up for the Solar as a Service plan that was introduced only a year or two ago.

It’ll be interesting to see where things are, even two years from now.