On the surface, sustainability with regards to building appears to be a very straight forward subject; if a building is built of materials that are readily and locally available, renewable, culturally relevant, and has minimal environmental impact; and, it is built to last a hundred, two hundred; let’s say, even a thousand years, then the building is a sustainable structure.
A 2004 survey, The Actual Service Lives of North American Buildings noted that the average life of a building in North America is about 30 years, which, by any standard, is not very sustainable. The study found that the largest percentage of buildings surviving is approximately 75-100 years of age. Of these structures, the largest number is residential, noted as primarily due to other factors “for example, older homes have characteristics valued by many people.” Only one third of concrete buildings lasted more than 50 years. Interestingly, the survey also states that, “Meanwhile, 80% of steel buildings fell below the 50 year mark, and half of those were no more than 25 years old.” Also noted, “some buildings in this category may have been considered unsuitable due to technical obsolescence of some components or systems, and an upgrade was deemed too costly.”
Buildings and building construction account for 39% of CO2 emissions in the US, making the industry the largest single contributor to pollution and energy waste. In an effort to counter this disturbing fact, we have begun as an industry to focus on building “sustainably”, or building Green. Building Green has many levels of achievement, the top of which is Platinum LEED. Logic tells us that many of the buildings that are being labeled “model” buildings for these programs are not really sustainable at all. Their materials of glass and steel are laden with the embodied energy of mining, manufacturing, and transportation, and in order to make these materials resistant to heat and cold they must be applied to a building in multiple layers.
A recent article in the UK by Thomas Lane, Our Dark Materials, notes that as much as 40 % of these buildings’ lifetime energy use comes from its materials and construction, “Embodied energy makes up a much greater percentage of a low-energy building’s total lifetime carbon footprint than one that uses lots of energy.” With regulation being eyed as a solution for the UK’s building industry the UK Green Building Council admits regulation “does raise tricky issues. These include the difficulties of comparing the merits of steel and concrete, a debate that has been going on for years.”