Greening Toronto's Concrete Slabs


Over a thousand of them were built in the sixties and seventies: monstrous twenty-five storey slab apartment buildings. And where TreeHugger usually says that high-density living is the most energy efficient, (and on a per-capita basis it probably is) these buildings are huge energy hogs, each building contributing more than a thousand tons of carbon dioxide per year. They have minimal insulation, exposed slab edges and balconies, single glazing and primitive heating. Welcome to Moscow on the Humber.

There is a bright side: two University of Toronto Architecture profs have studied the buildings and figured out that they may be the most cost-effective ways to reduce CO2 emissions in the City. (see some of their ideas below the fold) This has happened all over Europe and the former Soviet states; Tower block restoration is Bratislava, Slovakia's single largest environmental initiative. Unfortunately in Toronto these buildings are all in private hands, and no government in an election cycle is going to give its green subsidies to rich urban landowners. ::Reading Toronto

While glass window walls are the cladding fad of the day, the bulky masonry walls of these older slabs offer an ideal surface to support over-cladding systems. This approach extensively insulates the exterior of the buildings, encloses balconies and covers slab edges, which is predicted to halve energy requirements. Additionally, these buildings provide an economy of scale that makes geothermal heating, solar electric/water heating (locating panels on generous blank end walls), and green roof technology highly effective investments. These strategies would give the opportunity for carbon reductions of over two thirds the current output. In other words, a hundred and eighty unit apartment building would require less green house gas production than fifty traditional bungalows. Suddenly density begins to make sense.

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