A comparison of global bioclimates in the 20th and 21st centuries and building energy consumption implications

Summer and winter thermal discomforts in the major climate zones and sub-zones of the Köppen–Geiger world climate classifications during the 21st century were investigated and compared with those in the 20th century. Compared with the 20th century, frequency of distribution of the comfort index for the 21st century shows a distinct decrease in winter thermal discomfort and increase in summer thermal discomfort under the low and medium forcing emissions scenarios. Based on zone-average analysis, decreasing trends of cumulative cold stress and increasing trends of cumulative heat stress have been observed in all the major climate zones and sub-zones. There is an overall increase in energy use for space conditioning for all the sub-zones in equatorial climates, and an overall reduction in all the snow and polar climates sub-zones. In arid and warm temperate climates, the hot sub-zones have an increase in the overall energy requirements whereas the cold/warm sub-zones have a reduction. Locations within the hot summer sub-zones in warm temperate climates will become much more cooling-dominated, and there are significant increases in cumulative heat and proportional stresses in the hot summer sub-zones in snow climates. Implications for energy use and carbon emissions are discussed and mitigation/adaptation measures suggested.