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Construction Corner: Researchers find low-tech solution to reduce energy use

Korky Koroluk
Construction Corner: Researchers find low-tech solution to reduce energy use

Living in a high-tech world usually seems to mean that every gadget that’s invented is more complicated than the one that came before.

Tech seems to have a life of its own. The test is not whether a gadget is useful or not; it’s whether it’s got enough bells and whistles to qualify as high-tech.

It often seems that devising high-tech solutions becomes an end in itself rather than a means of solving a problem. So, it’s nice to know there are others out there who are looking for low-tech solutions to some of our problems.

There is word that a research group from the Technical University of Munich (TUM), in Germany, has come up with a low-tech way to reduce energy consumption in buildings with double-glazed facades.

Very little technical effort is involved.

Buildings like these are energy-guzzlers. They heat up like greenhouses so they have to be cooled for most of the year. It’s not uncommon to find that such buildings are being heated on the shady side while being cooled on the sunny side.

The leader of the TUM research team is Philipp Molter, an architect. He says his team’s approach to double-glazed facades is fundamentally different from the approach taken by other researchers.

“For decades, efforts to air condition glazed office…buildings have grown continuously more complicated,” he says. “We, on the other hand, are developing low-tech solutions that are also highly efficient.”

Molter and his team have developed a ventilation system for double-glazed facades that automatically opens when the temperature rises beyond a certain point and closes once again once the temperature cools off.

He notes heating and air conditioning for buildings worldwide presently accounts for 40 per cent of total energy consumption. Compared to residential buildings, skyscrapers with glass facades burn a lot more energy.

Molter says architects have long used a variety of what he calls “technical tricks” to prevent interior spaces from overheating. The conventional solution takes the form of slats or blinds on the building’s exterior. But since these blinds have to be protected against wind, a second external pane of glass is necessary.

This double glazing creates an airspace between the panes which heats up quickly and releases the heat to the interior spaces, which then need to be cooled.

That’s why double-glazed highrises are often equipped with ventilation slots. Closing these slots in case of cold weather or storms requires sensor technologies and many small electric motors. The whole system is controlled by the building’s central service computer.

Compared with these systems, Molter’s concept is really simple.

“Our model is the human skin. It protects us from overheating by opening up our pores. And that works automatically; we don’t even have to think about it,” he says.

At the centre of Molter’s system are paraffin-filled thermal cylinders. The wax-oil mixture inside the cylinder expands when the temperature rises above a certain point. The increase in volume generates pressure which extends the cylinder, like extending a telescope. When the temperature drops the cylinders contract once again.

The system, which Molter calls Ventflex, looks no different than conventional facade elements. However, the outer layer of glazing is not fixed in place, but is connected with the frame at all four corners by means of the thermal cylinders.

When the temperature between the panes exceeds 23 C the cylinders move the outside glazing five centimetres farther out. This allows cooler air to enter and naturally ventilate the cavity. When the temperature drops below 23 C the cylinders contract.

Molter says simulations show the concept to be extremely efficient. Compared with modern facades as much as half of the necessary heating and cooling energy can be saved.

Not much there for the lovers of complex systems. But if the system is installed and successfully operated for a while, it could prove that simple solutions can work.

Korky Koroluk is an Ottawa-based freelance writer. Send comments to

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