If I Could Modify the Passive House Certification Standards…

I would give credit for efficient use of space.

8/18/2011

8/19/2011 The GO Logic crew has left, the Certificate of Occupancy has been authorized, and Unity College staff are nearly finished setting up the furniture. Ready for our students on time!

The Passive House standard is the highest international standard for building energy efficiency. While it does not address some of the sustainability issues covered by the LEED standards, I hope that it influences LEED to adopt higher standards for energy efficiency than the USGBC currently promotes.

The Passive House certification requirements speak to minimizing thermal bridging, set a very high standard for air infiltration, and of course, require buildings to use 90% less energy for space heating than similar buildings.

From an energy conservation standpoint, though, the Passive House standard misses one key energy issue: efficient use of space.  The standard uses an energy per floor area measurement (<5,000 Btu/square foot) rather than an energy use per person measurement. While it may not be an issue in Germany, the home of Passivhaus, homes in the United States are getting larger all the time. Ironically, some of the most boasted about energy efficient homes in America may be 3000 square feet or more and occupied by only two people. On a square foot basis, the energy use is low, but it is much larger than it needs to be for comfortable living and hence the homes use far more energy than is needed.

Unity College and GO Logic went beyond the Passive House standard by seeking to provide comfortable housing for 10 students in 2186 square feet. After the first year, we will evaluate whether we have hit on the optimal number, but certainly we have achieved high density occupancy. Some of the design features used to achieve high occupancy, and, therefore, low energy use per student, include:

  • Careful attention to acoustical separation to provide privacy in bedrooms and bathrooms.
  • Open design for the kitchen, dining area and living area
  • Generous mudroom space with “cubbies” for outdoor gear
  • Use of white paint and large windows to increase the feeling of spaciousness
  • Separated shower and toilet facilities for efficient privacy
  • Individual thermostats in each bedroom
  • Good connection to outdoor spaces

I wouldn’t ask the Passive House folks to shift away from an energy per unit area requirement, but perhaps a provision could be added to modify the energy requirement for apartments and college residence halls designed to accommodate more than one person in 500 square feet. The effect on energy conservation would not be reduced because building footprints would shrink.

Not only would this accommodation send an important message about right-sizing buildings, but it could make the passive house standards more attractive for builders of apartments and college residences by increasing the options for appliances such as dryers and range hoods that carry the commercial ratings necessary to meet apartment fire codes. Unity College was happy to make the extra effort to overcome these hurdles so that TerraHaus can meet the Passive House certification standards. Once we are certified, though, we hope we will have earned a place at the table where these standards are discussed, reviewed and promoted.

Douglas Fox, Director, Center for Sustainability and Global Change

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1 Comment

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One response to “If I Could Modify the Passive House Certification Standards…

  1. Bruce E Landry

    Well this is the second time in week I had a conversation about energy per person as opposed to energy per sq ft. A 3000 sq ft passivehuas for 2 people still uses more toal energy, than does a 1500 sq ft super insualted tight house for 3 people. This isn’t even taken into account all the energy used in manufacturing, transporting and building the extra 1500 sq ft. A grad student in VT is writing a thesis on this very subject. I am in the process of design/build a Habitat for Humanity house this year. I would like to see credit for using local and recycled materials. We are going with a double 2/4 12″ wall system filled with cellulose. The framing lumber is recycled mostly from houses torn down due to tropical storm Irene
    high tech. We typically build small affordable

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