Basement Insulation

Energy efficiency is a primary reason for building a Green home. The average certified LEED Home uses 30% to 40% less electricity and will save more that 100 metric tons of CO2 emissions over its lifetime*. ENERGY STAR®, a program established by the U.S. Environmental Protection Agency, sets strict guidelines for energy efficiency and is a vital element of LEED for Homes and the NAHB National Green Home Program. The ENERGY STAR program includes requirements for an efficient home envelope, with effective levels of wall, floor and attic insulation.

The ENERGY STAR program utilizes the HERS® Index to rate the relative energy use of new homes. The HERS Index is a scoring system established by the Residential Energy Services Network (RESNET) in which a home built to the specifications of the HERS Reference Home (based on the 2006 International Energy Conservation Code) scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The lower a home’s HERS Index, the more energy efficient it is in comparison to the HERS Reference Home. Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home. Thus a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home and a home with a HERS Index of 80 is 20% more energy efficient.

HERS yardstick for this house

Others that recognize this index as well include:
· Mortgage industry for capitalizing energy efficiency in mortgages.
· Federal government for verification of building energy performance for Federal tax credit qualification and the U.S. Department of Energy’s Building America program.
· Sixteen states for minimum code compliance.


Since the basement of this home is considered part of the home envelope, it is important that it is completely insulated. After working with a certified HERS rater and performing many energy analyses, it was determined that R5, 1″ rigid foam insulation plus R13, 3 1/2″ of fiberglass would be required to obtain the HERS index rating needed for the level of LEED for Homes certification we planed to achieve. The R13 insulation will be installed later after the framing is completed.

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Insulation installed on the basement walls. View looking toward the Soutwest.

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View from the center of the Basement looking toward the Northwest corner.

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View looking toward the Northeast corner of the Basement.

*source: LEED for Homes Reference Guide, First Edition 2008. 

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