Active Energy Savings in Passive House

Imagine a warm, cozy home without any drafts, with warm floors and consistently hot flowing water. Then try to imagine that this house has no furnace, and that it gets all the heat and hot water it needs from the amount of energy needed to run a hairdryer.

Enlarge image A passive house, like this development in Darmstadt-Kranichstein, warms itself up with the warmth emitted by people and other internal heat sources. (© picture-alliance/ dpa) This is what is known as a “passive house,” and there are already approximately 15,000 passive houses around the world. Most are built in German speaking countries and Scandinavia, but there is also a growing passive house movement in the United States.

The first certified passive house in North America was the Waldsee BioHaus, built in 2006 at the Concordia Village German-language camp in Bemidji, Minnesota. Built with sponsorship from the Deutsche Bundesstiftung Umwelt, Europe's largest environmental foundation, it was awarded the Minnesota Environmental Inititative Award in 2007 for air quality and climate protection—the premiere environmental award in the state.

Buildings responsible for greenhouse gas emissions

For those of us not lucky enough to live or work in a building as carbon neutral as this, trying to reduce our energy usage probably means using energy efficient light bulbs, or turning the lights, heat and air conditioning off when we’re not there.

Unfortunately, such measures aren’t enough to prevent buildings from being one of the primary contributors of climate-changing pollutants to the environment. Data from the US Energy Information Administration shows that buildings are responsible for 48 percent of greenhouse gas emissions annually. So buildings that use almost no energy and emit almost no emissions may provide part of the solution.

Insulation is key

The roots of low-energy, passive houses actually lie in the super-insulated buildings designed after America’s first energy crisis in the 1970s. Yet the “passivhaus” concept was first developed by a Swedish professor, Bo Adamson, and a German physicist, Wolfgang Feist. The first prototype was built in Germany in 1990.  Feist founded the Passivhaus Institut (PHI)  in Darmstadt in 1996, and he still lives in the original passive house prototype to this day.

Enlarge image Styrofoam insulation plates are seen in front of a passive house row under construction in Darmstadt-Kranichstein. (© picture-alliance/ dpa) The name passive house (or the German passivhaus) was used because the heating energy requirement was so small that a conventional heating system could be replaced by a 1,000-watt electric-resistance heater. Such homes could be kept warm passively, by using only existing internal heat sources such as lights, appliances…and people!

To meet the basic Passivhaus standard, a building must consume no more than 15 kilowatt-hours per square meter in heating energy per year. This is achieved by constructing a building envelope—floors, walls, ceilings and a roof—that is extremely well insulated and air tight. A constant supply of fresh air is maintained by an energy-recovery ventilator, and the result is a building that uses 90 percent less energy than most others.

Growing movement in the United States

In Germany, passive houses now only cost about 5 to 7 percent more to build than conventional houses, and in the long run, according to the Passivhaus Institut, annual energy savings can be more than $1,000.

The concept was first brought to the US by Katrin Klingenberg, an architect born in East Germany but living in Urbana, Illinois. Her efforts to start building passive houses throughout the US led to the founding of the Passive House Institute United States (PHIUS). As of January 2008, PHIUS has been authorized by the Passivhaus Institut in Darmstadt as the official Certifier of Passive Houses in the US.

The added construction costs of passive houses remain more expensive in the US than in Germany, but an increasing number of passive houses are now being built. The 3rd annual North American Passive House Conference was just held in November 2008 in Deluth, Minnesota.