Timber Houses Lead a Double Life. As Carbon Sinks.

Today I was pushing my new son around in his stroller to lull him into sleep, when I happened upon a a steel frame house going up. Now I know there is often a goodly amount of recycled steel in such frames and they are very termite resistant. But still it got me pondering that old debate - steel or timber framed buildings? And I remembered a report I saw last month in The Age newspaper that suggested that timber frame houses were excellent carbon sinks. Not a trick that steel can replicate. According to research:

Almost 100 million tonnes of carbon is stored in timber in Australian houses, with about 2 million tonnes of carbon dioxide equivalent added each year as new houses are built ...

That annual addition would absorb about 0.4% of Australia's total greenhouse gas emissions (as measured in 2006), but has been on the decline as Australian houses have utilised more bricks, concrete, metal and plastics in the past 20 years. The study noted that were more wood used, "annual carbon storage in houses could rise from 1.6 million tonnes in 2008 to 4 million tonnes in 2050."

(Hey, maybe home owners can sell their carbon sink potential to the country's coal-fired power ultilities, if Australia ever fights its way out of long running political morass to eventually have an Emissions Trading Scheme? Not that current indicators look good.)

The report, entitled "Dynamics of Carbon Stocks in Timber in Australian Residential Housing" does need to be considered with a degree of circumspect, because it was commissioned by industry body, Forest & Wood Products Australia, who obviously have a vested interested in higher timber use.

However, industry influence aside, the researchers at Melbourne University's Department of Forest and Ecosystem Science, and the NSW Department of Primary Industries did collate some intriguing figures. For instance, they calculated that whilst most wood used in houses was historically sourced from Australian native forest or imported timber, these days 80% is derived from domestic softwood plantations.

And the study also found that "the average life of a house was 61 years, but wood product failure or decay were not the main reasons for demolition; these were site redevelopment (58 per cent) or the building no longer suiting (28 per cent)."

With such building churn, it becomes blindingly apparent why buildings chomp through 40% of raw material use.

Of course, as with the debate between paper and plastic shopping bags, it not necessary to choose either steel or timber. There are plenty of middle roads. For example, this writer would love to see more houses made of strawbales. An annual agricultural waste that also stores carbon, provides immense thermal insulation and easily lasts 100 years.

::Dynamics of Carbon Stocks in Timber in Australian Residential Housing. (PDF)

Photo: Forest & Wood Products Australia
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Tags: Architecture | Australia | Buildings | Green Building

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