An efficient climate index for reflecting cooling energy consumption: Cooling degree days based on wet bulb temperature

Abstract

Cooling energy consumption of buildings is not only used for decreasing temperature, but for dehumidification. Therefore, cooling degree day (CDD) based on only temperature is insufficient for estimating the cooling energy consumption in buildings. In the present study, we aim to propose an efficient climate index (i.e., CDD based on wet bulb temperature [WBT], WCDD) based on the combination of cooling energy consumption in a building and joint probability of temperature and humidity. In addition, the adaptation of the new WCDD was verified in 14 cities of different climate zones in China. The results showed that CDD based on dry bulb temperature (DBT) (DCDD) can only explain 17%–60% of cooling energy consumption, whereas WCDD explaining 86%–97% of cooling energy consumption in the different climate zones. The optimal base WBTs are generally 17.74, 19.44, 21.04 and 22.56°C for the four climate zones, respectively. The present study reveals that WCDD by combining effects of temperature and humidity on cooling energy consumption can be much more efficiently used to estimate the cooling energy consumption compared with DCDD. More importantly, the WCDD is suitable for reflecting the cooling energy consumption for different climate zones. The collaborative changes of temperature and humidity under the conditions of climate change should be fully considered to take measures for decreasing the energy consumption for decreasing temperature and dehumidification.