Cranking up the heater or throwing on an extra sweater are two ways to cope
with a drafty house that allows chilly air to seep in through cracks, doors
When the sun blazes in the summer, that same house warms up rapidly,
prompting people who live there to close the shades or drapes, pour an icy
beverage and possibly flip on an air-circulating fan.
A new concept in energy efficiency, known as the ``passive house,'' sets
specific standards for designing a home that reduces -- or completely
eliminates -- the need for a furnace or air conditioner. The home is
constructed to be super energy-efficient and to regulate air temperature in a
An airtight structure adhering to passive house guidelines could reduce
year-round energy costs by an estimated 80 percent.
It's been described as working like a sealed envelope or thermos bottle,
preserving hot and cold equally effectively. Heat generated by appliances,
bathing and the body itself are factored into calculations.
Accordingly, a house that's vacant most of the day would generate less heat
than one where occupants are using computers, TVs and kitchen and laundry
More than 10,000 passive houses have been built in Europe since the design
approach was introduced in Germany in the early 1990s. But only a handful have
been constructed in the United States.
Petaluma-based architect Bill Wolpert, principal of Green Building
Architects, has been interested in creating energy-efficient structures since
he was a student at Cal Poly San Luis Obispo in the 1970s.
Early in Wolpert's career, when gas, electricity and water costs were low,
energy efficiency wasn't a top priority. But now, most clients want buildings
that make abundant use of solar energy, have well-insulated walls, doors and
windows, conserve water and are constructed with recycled and/or nontoxic
Last year, Wolpert attended a lecture by Berkeley architect Nabih Tahan, a
passive house pioneer in California, and afterward asked two of his
residential clients in Sonoma County if they wanted to incorporate passive
house standards into their project, even though the design was nearing
The first certified passive house in the United States was built in Urbana,
Ill., in 2003 by German architect Katrin Klingenberg, who established the
Passive House Institute US. In January 2008, it was established as the
official certifying body in North America by the the Passivhaus Institut in
Passive house building techniques include use of the latest construction
materials, such as multipane windows containing a thin metallic film, argon
gas and a layer of mylar film, to create an insulating ``sandwich.''
A special feature is a central ventilation system with warm air moving
through it alongside cold air coming in from the outside. This heat exchange
is considered to be 90 percent efficient. An ``energy recovery ventilator''
provides a constant supply of fresh, filtered air and creates good interior
air quality while maintaining a comfortable temperature.
Previous efforts to create airtight construction have resulted in problems
with mildew and mold, Wolpert said.
Another key design consideration is positioning a house to take advantage
PASSIVE HOUSE ELEMENTS
From Passive House Institute US
* Mechanical ventilation with heat recovery
* Accurate climate and site-specific energy modeling
* Elimination of thermal bridges (insulation gaps)
* High-performance windows and doors
* Optimized passive solar design (solar gain in winter, shading in
* Passive House Institute US: passivehouse.us
* Passive House California organization: passivehouseca.org
* Passivhaus Institut: passiv.de (click on English for translated
* Bill Wolpert, Green Building Architects, 7 Fourth St., Petaluma,
* Graham Irwin, Remodel Guidance, 415-258-4501, remodelguidance.com
* Nabih Tahan, Berkeley architect, nabihtahanarchitect.com
Meeting of Passive House California organization, free and open to
2:30 p.m. today
950 Gilman St., Suite 210, Berkeley
ENERGY USAGE: An architect's rendering shows window locations
arranged to take advantage of where the sun and its shadow would fall
on the house from dawn to dusk. The design maximizes airflow and
incorporates walls with ultra-thick insulation. Energy consultant
Graham Irwin of Remodel Guidance in Fairfax provided the energy
analysis using software from the Passive House Institute US.