Sustainable buildings for a warmer world

The world is heating up and the rate of warming is, it seems, increasing. Buildings, even those in temperate climates, like the UK, must respond to these changes whilst limiting their emission of CO2, the primary greenhouse gas. The design challenge is exacerbated by the drive to develop brown field sites in an effort to contain urban sprawl. Tight, compact sites, urban noise and pollution and security concerns mean that the attenuated plan forms and operable windows, which are customarily associated with naturally ventilated buildings, are inappropriate – and the effectiveness of night ventilation is reduced by the urban heat island associated with large cities. In the UK, the CIBSE has recently suggested an overheating criterion which defines the upper limit of the summertime temperatures allowed in buildings. The criterion appeared simultaneously with new design weather data, which was much hotter than a typical year. All these factors tend to push designers towards the adoption of sealed mechanically ventilated and cooled buildings – which will merely exacerbate global warming. Hybrid buildings, a mix of natural ventilation and mechanical cooling, are touted as one solution. But can hybrid buildings have dramatically reduced CO2 emissions? Can they be cost effective? Can they meet all the functional requirements and maintain thermal comfort? And, critically, can they have architectural merit? This paper considers the temperatures which might be experienced in the UK up to the end of the century and examines the advantages and limitations of naturally ventilated buildings. Advanced naturally ventilated buildings, which utilise buoyancy driven stack ventilation, are discussed in some detail as they appear to offer an energy efficient solution to summertime comfort control and be robust to climatic change. Two large public buildings, the Lanchester Library in Coventry and the School of Slavonic and East European Studies in London, which address both the urban and climatic design challenges, are presented. The SSEES building is probably the world’s first large-scale public building with passive downdraught cooling.