FT : Glass, Concrete & Green Buildings
Monday, April 27, 2009
Grand Designs, the UK television programme that documents individuals’ ambitious residential building projects, regularly features houses based on wooden frames. It has even showcased homes made out of old car tyres, mud and recycled jam jars. Although these examples demonstrate that alternative materials can be used to make impressive buildings, steel, glass and concrete still dominate most constructions. Few people in the industry think these fundamental materials will disappear from building design in the foreseeable future. It is not, however, a foregone conclusion, according to Paul King, chief executive of the UK Green Building Council. He complains that in modern architecture, “there is an ascendancy of form over function” and questions whether glass and steel in particular should be the primary building materials. “Architects have become carried away with sexy structures,” he says. “And since the 1970s, there is an expectation that iconic buildings have to be made from glass and steel.” He also draws attention to the significant carbon footprint produced by the manufacturing process of the materials. “In 20 years, it is possible that such designs could become socially unacceptable.”
For the foreseeable future, however, the benefits of glass and steel will continue to outweigh their carbon cost. Glass provides natural light and is seen as the key to beautiful design, while steel has excellent tensile strength and is the best material for a strong frame on which to base the building. Phil Brown, regulatory marketing manager at Pilkington, the glass maker, says: “Producing glass might be energy-intensive, but the maximum payback time for that energy cost in most buildings is four to five years. Some buildings generate savings within a year,” he says. Modern high-performance single-pane solar control glass allows 70% of the light to pass through, he adds, while keeping out two-thirds of the sun’s heat and retaining as much of the internal warmth as a solid brick wall from 10 years ago. “And this is before we even start thinking about double-glazing,” he adds. “There is an expectation that most new buildings will have triple-glazed windows that have superior [heat retention] to an old cavity wall, too.” The European Concrete Platform, a trade body, says that concrete is “extremely versatile in terms of its structural and material properties” and that most buildings use it for “its strength, fire protection, sound insulation and, increasingly, for its thermal mass”. Marshalls, which makes concrete paving blocks, says it now uses waste products such as blast-furnace slag and pulverised fuel ash, from iron manufacture and coal fired power stations respectively, to reduce the embodied carbon dioxide in its concrete blocks by up to 39%. Combined with the benefits of its high thermal mass in terms of passive heating and cooling, concrete is likely to remain an important material in the future, particularly for the proofing of buildings against climate change.