Passive House 2 - Sustainable Design Article 4 - JB Hammer Designs

Passive House Article Two

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While pundits and ideologues politicize energy related issues, and the livability for future generations dangles in the balance, a handful of grassroots building professionals have been quietly pioneering new strategies for building the house plans of the future. Soon, government agencies, homebuilding giants, and the nation, will reap the benefit of their tireless efforts. The experimental will become mainstream and give us a truly sustainable energy efficient house plans at an affordable price.

Some day in the not too distant future, people will walk by this new breed of house and not notice a great deal of difference from today's homes. But in terms of hidden sophistication, it will be like comparing checkers to chess. In terms of power consumption, when renewable energy technology is added to these house plans, there will no longer be any comparison; they will require zero energy to operate (Net Zero).

Today, a buzzword linked to that house plan of the future is "Passive House (PH)." Developed in Europe and proven to be 70-80% more efficient than traditional construction, many have been built there. Today, only a handful have been built in the US (with many more in the works). Two of these revolutionary house plans were built in the Portland/Salem area.

The CoreHaus, in the North Tabor Neighborhood of Portland, was designed and built by architect Robert Hawthorne and home builder Bart Bergquist. It was built on speculation, but sold prior to completion. According to Hawthorne, the project costs were approximately 10% higher than standard construction with an anticipated 8 year recoup time for the additional costs (assuming a 3% increase in utility rates per year). After that 8 year period, it will be money in the owner's pocket for the life of the house because of the drastically reduced energy consumption.

Hawthorne says, "The design of a Passive House plan is much more difficult than a typical house since every detail has to be thought out in advance to avoid thermal bridging, to maximize insulation, and to make sure the air tight layer is not compromised during construction." While there are numerous approaches to building a PH, and some are very "revolutionary", Hawthorne chose a more "evolutionary" path by modifying standard methods to meet requirements. The bottom line for a PH; it has to meet the Passive House Standard of a 90% reduction in heating and cooling energy and an overall energy reduction of 65-80% over a traditional home.

While Hawthorne believes it may still be a while before the innovations used in the CoreHaus and other Passive Houses become mainstream, there is a "standardization" process taking place which is moving steadily towards that goal. Attributes of the PH which could create a snag in mainstream acceptance are its size and shape limitations. The green movement has been committed to smaller living quarters rather than larger. For certain ratio reasons, it is difficult for small house plans, particularly under 1000 square feet or so, to meet the PH Standard. This could be a drawback for those who want a smaller footprint. According to Hawthorne, a more realistic size for a PH is between 1000 and 1500 square feet. Another possible drawback is that more complex-shaped PH's are more expensive to build. If you take a liberty in one area, you need to compensate for it in another with more efficiency. That adds to costs. For example, a complex-shaped house plan requires higher insulation levels than a house plan with a rectangular form to maintain the same level of efficiency.

Other obstacles to overcome are; passive solar is highly desired on PH's and that can be difficult to comply with on some lots; and the amount of glazing and exterior door openings may need to be restricted to keep costs down and to conserve energy. While a house plan can break these rules and still be certified as Passive, more complex shapes, no passive solar, and more windows and exterior doors, require efficiency compensation in other areas which drives the costs up.

Hawthorne is now working on a PH duplex with a goal of Net Zero. That means he will be using the Passive House Standard to reduce the energy loads on the building, and then install a Photo Voltaic system (solar panels) to produce the required energy needs. The proposed goal; the building will produce as much energy as it consumes. He adds one last pearl of wisdom in the quest for the sustainable house: "Just because a house plan is efficient, does not mean it has permission to be ugly or not function well as a home.


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