Thermal comfort and energy-saving effects of medium-temperature operation strategy in conventional air conditioning systems:A case study of an office building in Shenzhen

To investigate the impact of a medium-temperature operation strategy in air conditioning systems on thermal comfort and energy-saving effects in the hot summer and warm winter zone, this study conducts a controlled experiment on an office building in Shenzhen. The experiment compares the medium-temperature operation strategy (9 ℃/14 ℃) with the conventional operation strategy (7 ℃/12 ℃) over two weeks with comparable meteorological conditions. Key findings indicate that the medium-temperature operation strategy maintains indoor temperatures comparable to those of the conventional operation strategy, but significantly increases relative humidity by 13.3%. Despite this substantial humidity increase, the thermal comfort acceptability rate under the medium-temperature operation strategy remains above 94%, attributed to the local occupants’ adaptation to the hot-humid climate and their higher humidity tolerance. Simultaneously, the medium-temperature operation strategy demonstrates significant energy-saving benefits, achieving a 13.0% reduction in total system energy consumption. Furthermore, the system’s coefficient of performance (COP) increases from 4.64 to 5.35, elevating the system from a non-high-efficiency grade (COP<4.7) to a level 2 energy efficiency rating (COP≥5.2).