February 21, 2011
Home owners these days are confronted with a dizzying array of products and services claiming to make their home more green. From high efficiency appliances and mechanical systems, solar, geo thermal, insulation and air sealing, how do people sift through the claims that companies make to determine the best use of their money?
The biggest part of making a home green is to minimize the energy use of the building. According to the Energy Information Agency 70% of all electricity consumed in the US is from buildings (21% from residential buildings). 50% of the energy used in America today is from operating buildings and these same buildings create 39% of the nation’s greenhouse gas emissions. So reducing energy consumption is job one for the green thinking home owner.
The best way to determine the energy performance of a home is to have a HERS rating energy audit done on your home. A HERS rating (Home Energy Rating System) uses a blower door and sophisticated software to determine the home’s actual energy efficiency. It is the “gold standard” for measuring and analyzing design performance and existing home performance. It is used by green certification organizations like LEED and Energy Star, as well as the mortgage industry and the IRS for tax credits and improved mortgage terms. Like a golf score, the lower the number, the better, with par being 100, average homes scoring between 130 and 150, and a net-zero energy home scoring a zero.
“You could say that a homes’ HERS rating is like a car’s MPG” says Nate Munson, whose company Evergreen Home Services, LLC has performed over a hundred ratings this past year. “The analysis has three major advantages. First it uses a blower door to de-pressurize the building to pinpoint air leakage and measure the natural ventilation rate. Second infrared imagery may be added to see exactly where heat transference is occurring. Third the software allows us to measure all the components that make up the building envelope. The report then ranks the components according to the amount of energy they use.”
Home owners can use the report to see which repair or improvement makes the most sense based on the energy and money saved. In most cases the biggest offender is air leakage. “We all know that a home has to breathe, but not hyper-ventilate” says Munson. Even in homes that are well insulated, air infiltration can significantly reduce the effectiveness of the insulation. After the air leakage is sealed, the blower door is used again to ensure that the sealing was effective, measure the performance increase, and verify that the home can “breathe properly”.
Michael Klement, principal of the well respected Ann Arbor firm Architectural Resource, agrees. He encourages homeowners that are considering additions or remodeling to start the process with a HERS rating “Energy management is a key component of our green design process. A HERS rating has proven to be a valuable tool to help our clients whether new, remodel or addition, establish real and quantifiable metrics for energy management and conservation”
The momentum towards more energy efficient homes continues on other fronts as well. Under new state legislation utility companies like DTE are required to provide incentives for saving energy. Homeowners can receive a $300 energy audit rebate if the have a HERS rating done and make at least one of the recommended improvements. Also available from DTEenergy are energy improvement rebates for air sealing, insulation, windows, etc. of up to $1,500. Under federal legislation the tax deductions or credits for home energy improvements have been increased to $1,500.
Many contractors and product vendors will rely on visual inspections or general assumptions to recommend home improvement. The HERS rating empowers a home owner with the knowledge and understanding of the energy performance of their own home, looking at it as an entire system. And that knowledge can save homeowners money and start them down the true path to being green.
Evergreen Homes Services LLC is a nationally certified home energy rating company and home performance contractor specializing in making you home more comfortable, affordable and efficient.
