Energy Star for Homes 3.0
Energy Star is probably the most widely recognized energy efficiency brand in North America. A recent study cited it as the second-most trusted consumer brand, right behind the Good Housekeeping seal. Critics of that study have objected that it was commissioned by the Good Housekeeping Research Institute, and that the sample was composed of subscribers to Good Housekeeping. If that’s true, it’s entirely possible that Energy Star is the most trusted consumer brand in North America.
Usually associated with consumer appliances, the Energy Star rating can also apply to new homes. More than one million homes have been Energy Star certified since the program began in 1996. In 2009, one in every five new homes built—more than 100,000 houses—was Energy Star rated. That’s pretty good market penetration for a voluntary program.
The current criteria for getting an Energy Star rating for a new home are relatively straightforward and not all that stringent. The house must have
- effective insulation, essentially RESNET grade 1-level installation;
- high-performance windows, with varying criteria based on climate zone;
- envelope and duct sealing;
- properly sized efficient heating and cooling equipment; and
- Energy Star appliances.
An important component of the certification process, which focuses on energy efficiency, is that these criteria must be verified by a certified, independent rater (typically a HERS rater with Energy Star-specific training). After verification, the builder receives an official Energy Star label for the home.
As we all know, the times are changing. Builders and homeowners are paying a lot more attention to more than just energy efficiency—factors like comfort, durability, indoor air quality, and resource consumption. To keep up with the changing times, the Energy Star program has redefined its criteria. The program applies to single-family homes, units in multifamily buildings that are three stories or less, and units in multifamily buildings up to five stories where each unit has its own heating, cooling, and water-heating systems. The program can, in theory, apply to whole-house gut remodels, but it will be difficult to get a gut remodel to meet all the requirements.
Welcome to Energy Star 3.0, also known as Energy Star 2011. It represents a necessary evolution of the Energy Star standard, which will continue beyond the 3.0 standard—EPA is already talking about Energy Star 4.0, a pathway to net zero energy homes.
An Energy Star 3.0 house must first meet a set of mandatory requirements in order to achieve certification. These requirements are documented in a set of four checklists.
Thermal Enclosure Rater Checklist
This two-page checklist, which is a refinement of the Energy Star 2.0 Thermal Bypass Checklist, includes detailed climate zone-specific requirements for window specifications, insulation levels and installation, air barrier alignment, and air sealing. The major changes from the Thermal Bypass Checklist relate to thermal bridging. Builders are offered several options for reducing thermal bridging, including SIP (structural insulated panel) and ICF (insulating concrete form) construction; double-wall framing; and advanced framing techniques. The builder may verify up to eight items on this checklist at the discretion of the rater.
HVAC Contractor Checklist
This two-page checklist, completed by the HVAC installer (or partially by the designer) for each installed system, includes whole-house ventilation design based on ASHRAE 62.2, heating and cooling system design relying heavily on ACCA J/D/S methods, and equipment selection. In addition, there are sections for recording the results of refrigerant calculations and testing, electrical measurements, and airflow and air balance testing.
HVAC Rater Checklist
This two-page checklist, completed by the rater, picks up where the HVAC Contractor Checklist leaves off. It includes duct installation criteria such as insulation, kinking, and pressure-balancing measures; duct leakage, whole-house and local exhaust ventilation testing and verifications based on ASHRAE 62.2 requirements; combustion appliance venting; and forced-air filtration.
Water Management Builder Checklist
The builder completes this one-page checklist, designed to improve moisture control, although the rater at his or her discretion may verify items. It includes requirements for site and foundation assemblies, such as slab vapor barriers; wall and roof assemblies, flashing and gutters; and building materials such as cementitious backer board in wet areas. You can substitute the Energy Star Indoor Air Plus Checklist for the Water Management Checklist if you like.
The home design—and ideally, the construction specifications—need to incorporate all the mandatory requirements, and the house has to pass the final verifications as well. Once the design meets the mandatory requirements, there are two possible certification paths: prescriptive and performance.
In order to qualify for the prescriptive path, the house must fit some conditioned floor area guidelines, as shown in Table 1. For instance, a 2,100 ft2 three-bedroom house can use the prescriptive path. A 2,300 ft2 three-bedroom house cannot. These guidelines are intended to make sure that the house fits within some relatively normal size parameters. The program doesn’t want to make it easy for, say, an 8,000 ft2 two-bedroom house to qualify.
If the home fits the conditioned floor area guidelines, you then have to design and build the house according to the Energy Star Reference Design, which contains climate zone-specific criteria for heating and cooling equipment, the building envelope and infiltration, and windows and doors. These criteria, while not terribly stringent, do provide a good baseline set of specifications for high-quality homes. For instance, the climate zone 3 criteria include
- 14 SEER cooling, or a heat pump if cooling equipment is installed;
- 80 or better AFUE (annual fuel utilization efficiency) furnace or boiler;
- radiant-barrier or Energy Star roofing when there are attic ducts;
- IECC (International Energy Conservation Code) 2009 insulation levels (R-30 attic, R-13 walls, R-25 floors);
- maximum ACH50 infiltration; and
- Energy Star windows (U-value ≤ 0.35, SHGC (solar heat gain coefficient) ≤ 0.30).
- water heater efficiencies, which vary by storage size and fuel type (for instance, 40-gallon gas units must be 0.61 EF [energy factor], electric units 0.93 EF, and oil units 0.53 EF); programmable thermostat;
- R-8 insulation on unconditioned supply ducts, R-6 on other unconditioned ducts;
- total duct leakage ≤ 6 CFM per 100 ft2 of conditioned floor area;
- duct leakage to outdoors ≤ 4 CFM per 100 ft2 of conditioned floor area;
- Energy Star appliances if installed; and
- 80% Energy Star CFLs or pin-based lighting.
Some of these requirements, such as duct testing, are simply a repeat of items on the mandatory checklists. Others are additional specifications that must be met. The Reference Design is summarized on a single page, with two pages of footnotes that reference additional resources.
The performance path requires energy modeling to determine if the house qualifies for Energy Star certification. It lets you trade off various aspects of the home design, as long as the total home performance is at least as good as the Reference Design. Currently, there are no software programs that incorporate Energy Star 3.0-compatible features, so the process sounds more complicated than it will be once the software support exists. Rumor has it that both EnergyGauge and REM/Rate are working on Energy Star 3.0-compliant versions of their programs.
Here’s how the performance path works:
- Use what’s called the Expanded Energy Star Reference Design Definition to calculate the HERS index of the proposed home. The expanded definition is very similar to the prescriptive path definition, with some additional details. You can complete this step by using existing software that calculates a HERS index—enter a building takeoff using the version 3.0 Reference Design parameters, then modify the items that are different in the Expanded Reference Design. Those items include slabs, crawl spaces, glazing, and heating and cooling equipment. The expanded design clearly identifies the differences between the two specifications.
- For all but condos and apartments in multifamily homes, if the home is larger than the matching benchmark size shown in Table 1, based on the number of bedrooms, calculate an adjusted HERS index for the house. This calculation, which should lower the target HERS index for larger houses, is shown in Table 2. This step penalizes oversized houses. For example, a 2,100 ft2 three-bedroom house does not need an adjusted HERS index. A 2,500 ft2 three-bedroom house must be adjusted by (2,200/2,500)0.25, or .97. If the initial target HERS index is 76, the adjusted target will be 74.
- Tweak your proposed design, making whatever changes you want, as long as the resulting HERS index does not exceed the target index calculated in step 2. In addition, all insulation, windows, doors, and skylights must meet or exceed IECC 2009 requirements. You can use on-site power generation to meet the target HERS index only for houses that are larger than the benchmark home, and only for the change in HERS index due to the size adjustment from step 2. For our 2,500 ft2 example in step 2, we can use PV only to lower the HERS index by 2 points.
- Once you settle on a set of design parameters that meet all the program requirements, build that house, incorporating all the mandatory measures. Have the builder, HVAC contractor, and qualified rater complete the checklists and apply for certification.
My descriptions of both the prescriptive and the performance paths skip over quite a few details and subtleties. For instance, there are exceptions for local codes that exceed Energy Star requirements and for manufacturer’s instructions that conflict with them. There will also be some state-specific modifications for those states, like California, that have more stringent energy codes. You need to get the complete Energy Star 3.0 documentation to get all the details.
The ScheduleEPA plans to start rolling out Energy Star 3.0 in January 2011. By the time you read this article, detailed guidebooks should be published, and builder, rater, and HVAC installer training should also be available. Because the program is a fairly drastic change from Energy Star 2.0, EPA has decided to make 2011 a transition year. The 3.0 specifications will go into effect, but with some wiggle room:
- All sections of the Thermal Enclosure Rater Checklist must be completed, but only section 3 (fully aligned air barriers) and section 5 (air sealing) must pass.
- The Water Management Builder Checklist and the HVAC Rater Checklist must be completed, but deficiencies won’t disqualify the home.
- Duct leakage to outside can be ≤ 6 CFM per conditioned square foot until 2012, when it reduces to ≤ 4 CFM per ft2.
- Total duct leakage has to be ≤ 6 CFM per ft2 starting in 2012. There is currently no threshold specified.
There’s no question that Energy Star 3.0 is more complex than its predecessors. It’s not yet clear how many builders will be willing to participate in this voluntary program. They will have to weigh the cost of complying against the increased revenue that participation might provide. All indicators are that green homes sell faster, and for more, than other homes. However, we’re in a tough economic environment. That distinction may not carry as much weight as it might have in the past. However, it may carry more.
A complaint often heard about other certification programs, such as LEED for Homes, is that they are too complicated and too expensive. I’m not sure I agree with those sentiments, but if the market does, then the reality doesn’t really matter. The same may end up being said about Energy Star 3.0. Although the end goal for most forward-thinking builders and energy codes is net zero homes, throwing more regulations at the problem may not be the best solution. A certification program like Passive House looks positively simplistic by comparison.
On the other hand, any process that results in better, more durable, safer, and more comfortable homes, new or remodeled, is a good thing. Energy Star 3.0 achieves that goal. The market will decide if it likes the program. Interestingly, LEED for Homes has said that it will be aligning itself closely with Energy Star 3.0 in its next revision. Also, there are some definite similarities between Energy Star 3.0 and California’s CALGreen building code, which goes into effect January 2011. From my perspective as a HERS rater and energy consultant, I would really prefer that there be one green-building standard. Even though Energy Star is a voluntary program, it’s the closest thing we have to a national standard for building high-quality homes.
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