Responses of air-conditioning loads to climate change and its impact on carbon emissions in the hot summer and warm winter climate

Energy consumption of air-conditioning in wet and hot climates is not only for cooling but, to a large extent, for dehumidification. Taking urban agglomeration in the Pearl River Delta region as a case study, this study analysed the cooling and dehumidification loads during the past 20 years. In addition, the impacts of cooling and dehumidification loads on carbon emissions were determined. The results showed that there was large spatial heterogeneity in the variations of the cooling and dehumidification loads. The cooling design loads in 1991–2020 was increased 1.83% to 5.56% compared to those in 1971–2000, while the loads for dehumidification was decreased 0.92% to 5.5%. Carbon emissions from cooling were increased, exceeding the carbon reduction from dehumidification, which leads to a weak increase in total carbon emissions. This study revealed that air-conditioning design should fully consider climate change impact by separating cooling and dehumidification loads, increasing the cooling load to avoid insufficient air-conditioning output but reducing the dehumidification load to promote energy efficiency of the air-conditioning system and to reduce carbon emissions. More importantly, an assessment of design loads with climate change in city or small scales should be made before determining summer air-conditioning system design capacity.