Image Credit: Postgreen (image 1), KB Home (image 2), Department of Energy (images 3 and 5), Earth Advantage Institute (image 4) One of KB Home’s Energy Performance Guide labels, whose monthly energy-cost estimate is, in this case, based on a design plan for the company’s Sebastian River Landing development, in Sebastian, Florida, and on local utility rates. The Department of Energy’s Home Energy Score is designed to allow homeowners to compare their home's energy consumption with that of other homes. A home energy assessor collects energy information during a brief home walk-through and then scores the home on a scale of 1 to 10, with a 10 indicating excellent energy performance and a 1 indicating the need for extensive energy improvements or energy upgrades. Green-building certifier Earth Advantage Institute piloted its Energy Performance Score labeling system in 300 homes in 2008 and launched it in 2010. Rather than rely on HERS Index ratings, the EPS system rates residential buildings' performance on a scale of 0 to 200, based on millions of BTUs used per year, with 0 being net zero. EPS, notes EcoHome magazine, also scores homes based on their carbon footprint, on a scale of 0 to 15, and provides annual and monthly energy-cost estimates. Presented as part of the Department of Energy’s Builders Challenge program, the EnergySmart Home Scale, or E-Scale, is an interactive tool designed to allow homeowners compare estimated cost and energy savings of new and existing homes. The tool is available at http://www1.eere.energy.gov/buildings/challenge/escale.html
This seems to be an especially busy time for the Residential Energy Services Network (RESNET), the national association of home energy raters and developer of the widely used Home Energy Rating System (HERS).
On February 14, KB Home announced that it had begun providing prospective homebuyers with an Energy Performance Guide, or EPG, for each model the company offers. The EPG, which resembles an automobile mileage sticker, includes an estimate of the average monthly energy cost of operating the home identified on the EPG. That cost is calculated using a HERS Index rating of the building based on an analysis of the building’s design, and on local utility rates. KB Home said the EPG program began this month.
The HERS Index uses as its reference a comparable home built to the specifications of the 2006 International Energy Conservation Code. Such a home would have a HERS rating of 100 – the reference point used for rating the performance of both older homes (which often score higher than 100 because they tend to be less energy efficient) and new homes such as those offered by KB Home (which are designed to meet the Energy Star standard and would therefore earn a HERS score lower than 100).
More RESNET-based ratings in the pipeline
But KB Home, which launched the EPG program to help it stand out in the market, likely will see other big builders hop on the energy-performance-label bandwagon fairly soon, and in fact RESNET’s executive director, Steve Baden, said in a recent note to RESNET members that other, similar strategic alliances with large homebuilders are in the offing. One with Pulte Group was announced last week.
Even though there is no national, standardized format for energy performance labels, including those pegged to HERS Index ratings, most of the variants adopted by builders as marketing tools tend to focus on clarity, simplicity, and estimated energy costs. Last week, for example, Nic Darling, marketing chief for Philadelphia-based builder Postgreen, blogged about a HERS-based home-performance label that he recently created. His sample label estimates the monthly energy cost for one of the homes in Postgreen’s Skinny Project, a trio of houses that includes one particularly narrow building. The Postgreen label includes a vertical bar notched with the HERS Index rating scale, which, in this example, runs from 0 (representing net-zero-energy performance) to 140 (close to the performance rating of many existing homes).
The Postgreen bar is marked to show that homes meeting Energy Star criteria earn an average rating of 85, making them about 15% more efficient than comparable homes built to the 2006 code. Postgreen’s Skinny, in Darling’s graphic, has a HERS rating of 24; his label also lists certain features of the house, such as the thermal resistance of its exterior walls and roof (R-38 and R-72, respectively), its triple-pane windows, solar hot water system, and 3 kW photovoltaic array.
A focus on dollar estimates
Comments posted to Darling’s blog were generally positive. Some suggested including more comparative performance information, and one directed readers’ attention to the Energy Performance Score developed by green-building certifier Earth Advantage Institute, which does not use HERS ratings but instead rates energy efficiency according to the MBTUs (million BTUs) a home uses annually. The EPS, which recently prompted a discussion on GBA, also indicates estimated carbon emissions (in tons per year) as well as average annual energy costs for the house in question.
The EPS system, developed in 2008 and now in use on a voluntary basis, has been praised for adding the carbon emissions data. But overall, feedback on the label seemed to come back to the priorities for other labeling systems – simplicity and the energy-cost estimate – the latter being piece of information homebuyers and homeowners are likely to relate to most readily.
RESNET and Passive House Institute U.S.
Another RESNET agreement, announced on Thursday, will address what is currently a very small segment of the residential market: homes built to the Passive House standard. RESNET says the agreement, forged with the Passive House Institute U.S., “synchronizes standards, modeling, quality assurance and quality control for low energy homes and buildings.”
The alliance means that Passive House Institute will become an affiliate member of RESNET, assign an HERS Index rating to Passive House buildings, and “adopt rating standards and procedures that harmonize with the RESNET provisions for Passive House certification, quality assurance, codes of ethics, and standards of practice.” The two organizations also agreed to adopt a uniform calculation of carbon savings for buildings built to the Passive House standard.
In a press release, Katrin Klingenberg, founder and executive director of Passive House Institute U.S., said that the alliance makes sense particularly because interest in Passive House now seems to be picking up. “By harmonizing standards with RESNET,” she said, “we expect Passive House to vault into the mainstream, where it belongs.”
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