Drawing on the experience of warmer climates for UK buildings
Learning from the experience of warmer countries as a response to changing conditions in the UK needs to be tempered with caution, as Dr Adrian Pitts told a recent CIBSE conference.Not only is the UK likely to experience some warming but also rather more variable climate in the future — according to most experts. That was the warning of Dr Adrian Pitts, senior lecturer in energy, environment and sustainability in the School of Architecture at the University of Sheffield, to CIBSE’s recent conference ‘Understanding and adapting buildings for climate change.’ His emphasis was on how facades and roofs interact with the climate to reduce the dependence on air conditioning and, even, heating. He warned: ‘Winter heating needs will continue to be substantial in the UK. Even in countries such as Greece, energy used for heating is more important than for cooling — taken over the whole year.’ With many buildings in the UK having life spans of over a hundred years, Dr Pitts stressed that new buildings and major refurbishments must be capable of dealing with the climatic changes expected over that period. ‘The resource cost, not to say economic cost, of rebuilding/replacing mistakes that are unable to cope with changing climate may be too high to bear for a second time.’ Other countries in the world have devised techniques to reduce the need for artificial cooling. ‘Around the world, there are many warm countries that make substantial use of natural ventilation or mixed-mode systems.’ However, the techniques used in other countries may not be directly applicable to the UK. For its latitude, the UK is relatively warm — because of the moderating effects of the surrounding seas and the warming effect of the Gulf Stream. Locations with similar temperature profiles to those of the UK are at lower latitude, so the Sun is higher in the sky. This has implications for both summer and winter. The low angle of the Sun in winter means that to exploit passive heat gain, the space between buildings must be 60 to 70% wider than in the south of France. The Sun is also lower in Summer, so that shading devices and overhangs must be wider than in the south of France — typically by 40 to 50%. ‘Technology cannot simply be transferred directly from locations with the same temperature profiles as that expected under a global-warming scenario,’ warned Dr Pitts. His expectation are for the UK climate to become more volatile, with, perhaps, wetter winters and warmer, drier summers. In response to such changes, Dr Pitts says that buildings will need to become better isolated from the effect of external climatic variables and more able to withstand climatic extremes and better able to be modified on a seasonal or, even, daily basis to match variations in the climate.