September 17, 2008

Green Building

Passivhaus technology offers evidence of Europe’s green revolution

SAUL CHERNOS

correspondent

They may be passive, but buildings built to rigorous Passivhaus standards for low energy use in Germany, Austria and elsewhere across Europe are anything but passive when it comes to having a small carbon footprint.

In a talk on sustainable building at the recent Green Building Festival in Toronto, Ronald Rovers, an associate professor with the Urban Environment Group at Wageningen University in the Netherlands, presented leading examples from Europe.

Thousands of Passivhaus (Passive House) buildings have been built in Europe, particularly in Germany and Austria. Rovers singled out a handful, including Energon, in Ulm, Germany.

Completed in 2002, the futuristic-looking four-storey office complex features triple-glazing and a glass-covered atrium that helps circulate air and bring daylight into the inner office spaces.

Heating and cooling is transferred within floor slabs and enhanced by strong insulation and an airtight envelope. “You reduce your energy needs by every means possible,” Rovers said, citing features such as daylight planning, ventilation and heat recovery, heat-exchangers, and photovoltaics.

In the Region of Wels in Austria, the Factor 10 research program renovated an 8,000-square-metre school to achieve the passive house standard for an existing building.

“It needed renovation anyway,” Rovers said, pointing to skylights for daylighting and faades insulated with natural, grown fibres. “The energy consumption was brought down from 165 kilowatt hours per square metre to 15, so you can see there is more than a factor 10 improvement.”

Emphasizing the use of locally-sourced renewable materials, Rovers showed a slide of a five-storey timber-frame straw-bale house in Amsterdam.

“It has wall heating and is plastered with loam,” he said, adding that researchers in Scandinavia have found that gypsum board can help prevent fire moving between storeys in wood constructions, with residences of up to eight storeys being built in countries such as Sweden.

Energy efficiencies aren’t just limited to buildings. “Asphalt is an ideal collector of heat,” Rovers said, explaining that systems are used to store the heat underground and then either pipe it to nearby buildings or use it to defrost route surfaces, with experiments looking into electricity generation.

“We have the technology. We have proven that we can develop zero-energy buildings, so the problem is more policy and economic than technological or design.”

Occasionally, there is political will. Johanna Ekne, environmental strategy unit project manager with the City of Malm in Sweden, described her municipality’s transformation from largely manufacturing and industrial into an environmentally-friendly city with a knowledge-based economy.

Over the past decade, a university has opened, and areas such as the Western Harbour have been cleaned up and rebuilt for residential and mixed-use.

Designed for pedestrians and cyclists, the neighbourhood includes a bird habitat, abundant green spaces, and living roofs, complete with the collection and use of rainwater for plants and ponds. The area generates all of its energy from local, renewable sources. Aquifers in the bedrock, solar collectors and biogas generated from organic residues produce heating and cooling. Wind power and photovoltaics create nearly 100 per cent of the electricity needed. And, rather than hide features such as solar collectors, these are integrated visibly into the architecture, Ekne said.

While Sweden isn’t blessed with ample sunshine, the government has provided grants to help the city manage the project.

“There was a lot of work done in the beginning to get everyone on board,” Ekne said, adding that the project was based on a municipal master plan.

“We were fortunate to have a mayor who is an architect, there was a strong political will from others, and we’ve had the same political situation for a long time, which makes it possible for us to work long-term.”

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