The Austrian Passive House Group Visits Canada: Promoting the Building of Tomorrow

bridges vol. 11, September 2006 / Green Buildings Focus
by Guido Wimmers

Living in a passive house can be described as a 365-day stay in a climatic spa. Fresh air flows in constantly, but traffic noise, insects, dust, soot, and pollen remain outside while no heat is lost. No cold building surfaces generate asymmetrical radiation temperatures. All surface areas are equally warm - even the windows. The result is simply a healthy and comfortable indoor environment.

Although occupants of passive houses may open windows whenever they want, they won't have to. A passive house is continuously supplied with fresh air via the ventilating system and, because of the heat recovery, it always has a comfortable temperature. This has several advantages: unlike window ventilation, fine filters in the ventilating system keep out dirt and pollen; and air quality within the house is always excellent, even when occupants are away and/or windows are never opened.

The ventilation system with heat recovery in a passive house is not an air conditioning system that recirculates inside air. Bacterial growth can be a problem in recirculation air systems with cooling, but only if they are poorly maintained. Fan and valve noises are almost completely eliminated by sound control measures like vibration isolation mounts and low air speed. Jet nozzles guide incoming air along the ceiling, from which it uniformly diffuses throughout the room at barely perceptible velocities.

Does this sound like a house you'd like to live in? Welcome to the building of tomorrow!

{access view=guest}Access to the full article is free, but requires you to register. Registration is simple and quick - all we need is your name and a valid e-mail address. We appreciate your interest in bridges.{/access} {access view=!guest} The Austrian passive house group (APG) visits Canada
In September 2006, a delegation from the Austrian passive house group (APG) visited British Columbia. The members representing APG were Austrian market leaders in the field, with long-term experience in the conception, design, and construction of passive houses. Some of their products have become known and respected worldwide.

Initially, APG was interested in the state of the art of passive houses in British Columbia. Eventually, the passive house know-how of APG will be transferred to Canada, to better establish passive housing through contacts and further cooperation. There have been great advances in Canadian awareness of energy concerns. It is the APG's objective to strengthen this progress by offering technological assistance.

apg_vancouver_caption A further goal of APG is to strengthen cooperation with the academic sector, launching a competition between students of the University of British Columbia and the University of Innsbruck, Tirol. The objective of this competition will be to determine innovative ways of approaching timber construction and methods of energy-saving construction in both countries. Doing so will enhance the environmental awareness of the participants, as well as their technical abilities for planning and constructing the next generation of energy-efficient houses.

In addition, informative preparatory discussions have already been held with the green building council, and the APG is especially eager to present their kind of modern architecture in the surroundings of the 2010 Olympic Winter Games in Vancouver, British Columbia.

How does a house qualify as "passive"?
The passive house standard originated from cooperation between the PHI (Germany) and Lund University, and may be described as an enhancement of the low-energy-building standard. It combines the advantages of the "passive solar design" with the "super-insulated design" and marks an end to the related controversy. The passive house (including its special technology) can be applied to new building construction and to renovation.

In a passive house, a comfortable interior climate can be maintained without active heating and cooling systems (Adamson, 1987; Feist, 1988). The house heats and cools itself "passively," thus the origin of its name. The trick is to construct a building that loses practically no energy. This requires high isolated compounds, triple-pane windows, no heat bridges, and air leakage of no more than 0.6 times the house volume per hour when the house is pressurized to 50Pa by a blower door. The little energy still required is mostly produced with a small heat pump.

In Europe, the definition of a passive house requires that the annual heating energy be less than 15 kWh/(m²a) (4755 Btu/ft²/yr) and the specific heat load for a heating source at design temperature must be less than 10 W/m². Furthermore, the primary energy consumption of the living area may not exceed 120 kWh/(m²a) (38039 Btu/ft²/yr) for heat, hot water, and household electricity combined.

This means that the energy consumption for heating would be similar to or less than 1.5 liters of oil/m². Therefore, the combined end energy consumed by a passive house is less than a quarter of the energy consumed by the average new home constructed in Europe. Compared with normal US houses, passive houses in Austria use as little as one-thirtieth the energy for heating, cooling, and hot water. Using these new standards, energy consumption in US households could be reduced by 97 percent.

Even more remarkable, if a house built close to "passive house" standards uses renewable energy (solar cells, solar thermal energy, wind energy, biofuel, or an earth-heat exchanger), it can even generate more energy than it uses. Such buildings may be called "energy-plus houses."

History of energy efficient houses
The history of highly energy efficient houses dates back to the 1970s. Back then, US Americans and Canadians, motivated mostly by rising oil prices, started to deal with this topic. By 1976 technical terms such as "super-insulation" were introduced by the University of Illinois. The so-called "Saskatchewan house," built in Regina in 1978, was ahead of its time and influenced construction methods for the next decade. However, with the decline of energy prices, the movement stagnated.

In the mid-80s, in an environment of ecological sensitization, the development of energy-saving buildings progressed once more. The term "passive house" was introduced, mainly in Germany, and mostly defined by Dr. Feist´s physical data. Since the mid-90s, the number of passive houses has constantly grown, typically doubling each year. The spread of this type of construction has been especially rapid in Austria. As a result, over 1000 passive houses have been built in Austria. The number of passive houses in Europe is estimated at 4000-5000, and is expected to double again next year. For that reason, we can no longer speak of "the houses of tomorrow" but rather "the houses of today."

Our present day is distinguished by exploding energy prices and knowledge of the ecological damage caused by fossil fuels. These circumstances force us to think in terms of a sustainable lifestyle. The Austrian passive house group and their colleagues - in Canada and throughout the world - will continue their work to make "tomorrow" arrive "today. "


The author of this article, Guido Wimmers, is an architect based in Innsbruck, Austria, and specializing in the creation of low energy consumption concepts for new buildings. With this qualification he works at the Energy Institute of Tyrol in Austria.