Thursday, October 09, 2008

Aesthetic appeal, sustainability combined in “Passive House” under construction north of Urbana

Aesthetic appeal, sustainability combined in “Passive House” under construction north of Urbana

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Two miles north of Urbana, Margaret and Gregory Stanton are building a new house on the site of Margaret’s childhood home, where they plan to live in retirement. When it’s finished, from the road you’ll see an attractive, prairie-style house that’s two stories in the center with a single story annex on one side and a generous wraparound porch.

What you won’t be able to see from the road is that this is the house of the future.

The Stanton house is being built to the world’s highest standard for energy-efficiency, certification as a Passive House. (Here “passive” means that the house will require little, if any, heating beyond the warmth naturally generated by people, appliances, and lighting.) This standard was developed in Europe, where some 10,000 buildings have been built or remodeled to meet it in the past 10 years. The Stantons learned of the Passive House standard through Katrin Klingenberg and Mike Kernagis, who together founded and operate Passive House Institute U. S., which is headquartered in Urbana. The institute is actively engaged in a wide range of activities to further the implementation of Passive House standards and techniques nationwide, including education, research and consulting.

I call the Stanton house the “house of the future” because it represents a giant leap forward in energy-efficiency, but I should emphasize that this leap is accomplished with technology and materials that are readily available today, and at a very modest premium in the cost of construction.

To meet the Passive House standard, the Stanton house will minimize thermal losses. This means, in part, that it is extremely well insulated. The envelope of the house is made up of two components, both of which are filled with insulation: an exterior wall composed of 12” thick, box-like panels, and an interior wall built on 2 X 4 studs. The slab on which the house is built and the roof are both also super-insulated. In addition, all of the windows have three panes, rather than just two. Thermal losses are further minimized by the great care taken to eliminate air leaks, so no pipes or electrical conduits penetrate the exterior wall. In all, these measures prevent the transfer of heat up to three times as well as typical new construction.

In addition to minimizing thermal losses, Passive Houses are designed to maximize thermal gains. The Stanton house will take advantage of the warmth provided by the sun in winter with glass doors and extensive windows on the south side.

The materials used in the construction of the Stanton house were also chosen with regard for their overall impact on the environment, from the types of insulation used, to the floor finishes, paint, and exterior siding. In addition, the systems that use energy in the home, such as appliances and lighting, are as efficient as possible, and a solar system is used to supply hot water. The Stantons were even able reuse materials that they salvaged from the house that Margaret grew up in, especially the Douglas fir roof framing, which has gone into the exposed architectural beams, railings, and trim of the new home.

For the extra investments the Stantons have made in the construction of their home, they expect to reap substantial benefits. They anticipate spending 70-80% less on gas and electric bills, and using 90% less energy for heating and cooling than they would in a conventionally built house. They will also be living out the principles of good stewardship held by Margaret’s late mother, whose example of sustainable living led to the couple’s interest in the Passive House concept.