Unenduring C
Industry can genuinely improve sustainability by taking embodied carbon into account and extending the lifespan of our buildings, writes David Telford
limate change is the most serious global sustainability issue and the energy required to operate buildings a major component of global emissions. As a consequence,
considerable efforts have gone into reducing buildings’ operational energy by improving the energy efficiency of the building envelope. However, this approach only partly meets the challenge of making our buildings more sustainable. The latter half of the last century saw the economic
life of non-domestic buildings fall considerably. Poorly constructed commercial blocks of the 1960s and 1970s are increasingly being pulled down because they are seen as no longer fit for purpose – and have, in effect, exceeded their economic life. Apart from recovering steel frames and a little of
the concrete as low-grade aggregates, the materials that went into them are lost or only available in a very degraded form. If we compare this situation with the best of Victorian and Edwardian construction, we see a very different picture, with basic building structures preserved and remaining fit for purpose and reuse. In sustainability terms, the natural resources invested in their construction are still yielding a return. However, we are still designing buildings that, in 40
years’ time, will no longer be fit for purpose and will not be able to be economically refurbished. In an effort to cut costs or, simply to get projects off the ground, we are in danger of repeating past mistakes.
Renewal A modern low-energy commercial building will have a core structure that has a useful life well in excess of 100 years. The shell may well have a useful life in excess of 50 years, while some services can be expected to last for around 30 years and the interior fit-out for 20 years. As we move to a more carbon-constrained future, we
will not be able to afford, in energy terms, to demolish buildings and degrade and lose high-embodied energy materials. Although we are seeing improved demolition
34 CIBSE Journal July 2010
www.cibsejournal.com
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