How do we go about designing buildings today for tomorrow’s weather? As the world warms and extreme weather becomes more common, sustainable architecture is likely to mean one major casualty: glass.
For decades glass has been everywhere, even in so-called “modern” or “sustainable” architecture such as London’s Gherkin. However in energy terms glass is extremely inefficient – it does little but leak heat on cold winter nights and turn buildings into greenhouses on summer days.
For example, the U-value (a measure of how much heat is lost through a given thickness) of triple glazing is around 1.0. However a simple cavity brick wall with a little bit of insulation in it is 0.35 – that is, three times lower – whereas well-insulated wall will have a U-value of just 0.1. So each metre square of glass, even if it is triple glazed, loses ten times as much heat as a wall.
While the climate is changing, so too is the weather. Climate is expressed in terms of long-term averages, whereas the weather is an expression of short-term events – and the weather is predicted to change by much more than our climate. This creates challenges. A 0.5℃ increase in monthly temperature can made a difference to farmers, or the energy used by an air-conditioning system, but a peak temperature of 38℃ or a vicious cold snap can be far more serious. Buildings are designed to handle extremes, not just averages.
Architects and building engineers around the world are now having to struggle with this issue, especially since buildings last so long. At Bath we have recently been awarded a grant to look at long-term weather forecasting and how building design will have to change. After all, you can’t move buildings to a better climate.
One obvious possibility, for UK designers at least, is that they pick a place where the weather currently is similar to what the Met Office suggests the UK will have in 2100, and simply put up buildings like the ones they have there.
The problem is this ignores the low-carbon agenda. Many hot countries have spent the past 30 years designing buildings similar to those found in more temperate countries, while leaving enough space for monster air-conditioning systems. The air-conditioned skyscrapers in Las Vegas and Dubai, for instance, look just like buildings you might see in London or Boston, despite being built in the middle of a desert.
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