The possible shift between heating and cooling demand of buildings under climate change conditions: Are some mitigation policies wrongly understood?

Global warming affects the built environment by changing the environmental conditions under which buildings operate. This change probably means a shift in thermal demand, from a predominant demand for heating to a higher demand for cooling in many climates. For instance, in cold climates global warming seems to be a self-decreasing phenomenon because of lower energy demand in warmer environments. In warmer climates, like the Mediterranean, and in the hottest climates (both humid and arid), global warming must be regarded as one of the main factors (the others are the change in comfort standards and the heat-island effect) in increasing the energy demand to cool buildings. This chapter analyses the environment of various cities, characterised by mild average temperatures and small thermal oscillations, that can be regarded as Mediterranean climate emplacements. Today these cities have more heating than cooling demand but in the future will probably have higher cooling requirements. Results show that by 2050, in most of the considered emplacements, cooling demand will be higher than heating demand and emissions will rise proportionally. Solutions to this problem must be sought in the flexible operation of buildings, and policies should focus on summer-related issues: good natural ventilation, protection from the sun, and internal gain reduction, rather than insulation, air infiltration reduction and solar access.