Are Green Buildings just Houses Painted Green?
Last Post 30 Apr 2009 08:11 AM by Hoowood. 0 Replies.
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30 Apr 2009 08:11 AM

If you had asked someone a decade ago, "Can you imagine living in a green building?" the answer would probably have been, "You mean my house painted green? Nah, it's not really one of my favorite colors . . ."

Unfortunately it's impossible to think of an equally ambiguous question in German to compare public awareness of ecological concepts with that of Austria ten years ago. "Oekohaus" might just be mistaken for the house of a person with a particular "political agenda." Perhaps if you asked people what they think of "Nachhaltigkeit" in Europe or "sustainability" in the US, some might be at a loss. However, if you asked if they would like to live in a "Low-Energy House" the results would be quite different from ten years ago.

This ambiguity forces us to consider the multitude of meanings bundled under the wide umbrella of "Green Building." Energy efficiency is often considered a significant part of sustainable building concepts - indisputably important, but not the only indicator of an ecologically valuable building. In Europe, people tend to point their fingers across the Atlantic when discussing energy efficiency and squandering resources. European houses in general are more efficient in terms of energy used for heating and cooling. However, this is more an economic than an ecologically-driven development. Energy is more expensive for European consumers, so it makes sense to invest in more efficiency. When it comes to sustainability this competitive edge can quickly diminish. Here we have to look at the life cycle costs of materials we use to achieve this goal - for example, the embedded energy needed for production and demolition of extruded foam insulation panels.

With that in mind, I want to discuss the idea of Green Buildings against the background of academic education, public incentives, mass production, and the general public awareness of sustainability for buildings.

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. "

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