Building Energy Saving for Indoor Cooling and Heating: Mechanism and Comparison on Temperature Difference

Reducing the heat transfer temperature difference via reasonable indoor temperature determination and air conditioning system design is a confirmed building energy-saving approach for space cooling and heating. However, the energy-saving mechanism cannot be explained scientifically and comprehensively while maintaining the cognitive level of the heat transfer law. In this paper, based on the same climatic conditions and decreasing range of indoor and outdoor temperature difference, the yearly and monthly absolute energy-saving amount (ESA) and relative energy-saving ratio (ESR) are investigated and compared for cooling and heating, respectively, to reveal the energy-saving mechanism for cooling and heating from the microscopic perspective. Two new concepts, including ESA by temperature difference and behavioral ESA by measure itself, are defined. The yearly ESA for cooling or heating caused by the decreasing of temperature difference is composed of those two factors. For cooling, the contribution rate of the behavioral ESA at those moments within the decreasing range of the temperature difference can be up to 78%, while for heating is only 7%. This work can provide theoretical support for building energy system design optimization and method reference for energy-saving analysis of building air conditioning systems with temperature difference considerations for cooling and heating, respectively.