The influence of occupant control behaviour on thermal comfort under different heating charging modes in residential buildings in cold regions

In China's central heating, there are two modes for calculating heating costs, which are divided into Charging by flow mode which charges according to the amount of use and Charging by area mode which charges according to the floor area. The Charging by flow mode has been increasingly adopted by numerous urban central heating buildings. Thus it is worth investigating whether occupants experience varying levels of thermal comfort under these two modes. To address this, a field test and subjective questionnaire survey were conducted on residential buildings in cold regions of China during the heating season. The study assessed 134 residential occupants utilizing radiator heating, comprising 66 in Charging by area and 68 in Charging by flow modes. A collection of 1206 valid data points was obtained, with 609 in Charging by area mode and 597 in Charging by flow mode. The findings reveal noteworthy disparities in the duration, area, and strength of heating equipment usage between the two modes. While there are no marked variances in the interior and exterior environmental conditions under both modes, residents in the Charging by flow mode experience enhanced thermal comfort, acceptability and expectation, as well as better air quality satisfaction. Perceived control can greatly enhance individuals' thermal sensation in temperatures below 18 °C and above 24 °C. The impact of perceived control on thermal expectation is linear with temperature adjustments. The heightened degree of sensing control in Charging by flow mode lowers residents' expectations of high temperatures, broadens the range of acceptable low temperatures and accomplishes energy conservation and carbon reduction while ensuring optimal comfort.