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Energy Star Homes

In 1992 the Environmental Protection Agency established the Energy Star program to label energy efficient products and reduce energy usage and carbon dioxide emissions across America. Today, the Energy Star program encompasses 40 product categories and is widely recognized as the mark of energy efficiency for electronics, appliances, and even homes. The Energy Star for Homes program aims to reduce the energy consumption of one of America’s largest energy uses. According to the EPA, homes account for 15% of energy consumption nationwide. New homes that demonstrate a certain level energy saving improvements earn the Energy Star label. Energy Star homes save homeowners money in utility bills. In addition, Energy Star homes:

Have higher appraised value
Qualify for Energy Efficient Mortgages and Tax Credits
Are more durable and comfortable

Using structural insulated panels (SIPs) in residential building can easily qualify a home as Energy Star. A SIP building envelope has an extremely high whole wall R-Value and low levels of air infiltration, reducing the overall loads for heating or air conditioning equipment in the home. To read more on how to achieve an Energy Star Rating using structural insulated panels

WHAT MAKES A HOME ENERGY STAR

For a home to earn Energy Star certification it must be tested for energy efficiency using a Home Energy Rating System (HERS) index. A HERS index is an objective and standardized measurement of how much energy a home uses.

HERS raters calculate the HERS index through an onsite home inspection and using computerized energy modeling software. The HERS rater will perform a visual inspection and then a few tests on the home. A blower door test is used to determine the airtightness of a home by using a computer controlled fan to depressurize the home and measure the amount of air leaking out. A duct blaster test is also performed to measure the amount of leakage in forced air ducts through a similar process. Homes built with a complete structural insulated panel building envelope are so airtight that neither of these air leakage tests are required to achieve an Energy Star rating.

The HERS rater will use the data from these tests and his onsite inspection to help him calculate the HERS index through energy modeling software. The software will take into account the kind of appliances, heating and cooling equipment, levels and quality of insulation, and other factors, to calculate the projected energy use of the home. The house is scored in reference to a theoretical house designed by the software to the specifications of the 2004 International Energy Conservation Code (IECC).

A home built to 2004 IECC standards has a HERS index of 100. The other end of the spectrum is a Zero Energy Building (ZEB) with an index of 0. ZEBs use net zero energy by producing as much energy as they consume.

A HERS index is accompanied by a HERS report. The report includes the projected energy costs for the home. Every 1 point decrease in HERS index equates to a 1% reduction in annual energy costs compared to the IECC reference home.

For a home to be rated Energy Star in the central northern portion of the United States, it must have a HERS index of 80. Homes in the south and costal areas must have a HERS index of 85. For a map of HERS requirements by climate zones, visit www.energystar.gov/homes.

In addition to achieving the required HERS index, Energy Star homes must pass a sixteen point Thermal Bypass Checklist. The checklist insures that the home receives the full R-Value of the insulation used in the home by inspecting for gaps, voids, and potential areas of insulation compression. The primary item on the checklist is that a whole house air barrier be installed such that it will, “provide continuous alignment of the insulation with the air barrier,” something that is almost automatic with structural insulated panels. SIPS AND ENERGY STAR

Building with structural insulated panels (SIPs) can cut home energy consumption by up to 50%, making it easy to reach Energy Star qualifications with SIP homes.

SIPs provide high density foam insulation consistently and flawlessly, without the voids, gaps, and compression of insulation in stud walls, studies done by Oak Ridge National Laboratory (ORNL) show that when whole wall R-Value is measured, SIPs far outperform wood framed walls. By eliminating the loss of heating and cooling energy through gaps in the insulation, SIPs dramatically reduce the amount of energy used to heat and cool a home.

In addition to providing a high level of insulation, SIP homes are significantly more airtight than conventionally wood frame construction. The foam core of a SIP panel functions as a complete air barrier, and working with large panels means there are fewer joints to seal. ORNL evaluations of a SIP test room revealed the SIP room to be 14 times more airtight than an equivalent room with 2x6 construction, sheathing, insulation and drywall. For this reason, the EPA does not require a blower door test for homes built with SIP walls and a SIP roof.

Air tightness is extremely important when reducing a home’s energy usage. As much as 40 % of a home’s heating and cooling loss is due to air leakage. Passing the required Thermal Bypass Checklist is practically automatic when building with SIPs. Properly installed SIPs provide the whole house air barrier that the checklist requires, and if a SIP roof is used as well, many potential problem areas of air leakage are already inside the conditioned space.