Net-Zero Duplex Makes A Concrete Statement

When they started the project, a solidly sustainable dwelling was the goal. Then the builders of a Habitat for Humanity duplex in Edmonton, Alberta, realized they had a shot at net zero – so they went for it.

And here’s the real kicker: This is a building constructed of precast concrete.

Putting the panels in place. (image from Habitat for Humanity Edmonton video)

Putting the panels in place. (image from Habitat for Humanity Edmonton video)

The North America division of Lafarge, one of the world’s largest cement makers, was the driving force behind the Habitat for Humanity Net-Zero Duplex project, working with the architecture and engineering firm Stantec. The building this week was named 2013 Project of the Year and the Sustainability Award winner by Alberta Construction Magazine

Families have moved in to the duplex, but Lafarge isn’t moving out so quickly. The company has called the project “an experiment in sustainable design and construction,” and said that over the next two years, MIT will monitor the homes’ energy performance. If the building measures, Lafarge could try to make it more than a one-off.

image from Habitat for Humanity Edmonton video

image from Habitat for Humanity Edmonton video

The great benefit of concrete is its ability to retain thermal mass as the season demands – staying cooler in the summer, and warmer in the winter (a particular issue in way-north Edmonton, of course).

The panels for the duplex were precast at a Lafarge plant in Edmonton. They have an insulation rating ofr R44 for the walls and R88 for the roof, about three times the insulation of a typical home, Lafarge said. The company sees other benefits from the concrete construction: “Concrete also makes the home safer in the event of fire, increases sound resistance, and reduces the amount of on-site construction waste.”

While the concrete makes the building less of an energy hog, it doesn’t mean it uses no energy, of course. So to be net zero the duplex produces its own heat and hot water with a geothermal system, and a photovoltaic  panels on the provide electricity.

Here’s a video, produced by the project’s developers, that tells more about it:

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.