Effectiveness of the thermal mass of external walls on residential buildings for part-time part-space heating and cooling using the state-space method

A high-resolution time interval numerical model is more accurate to analyze the building dynamic thermophysical processes in the intermittent occupancy, while relevant professional software, such as EnergyPlus, is not compatible with different time intervals. The present study aims to investigate the thermal mass effectiveness of external walls on the part-time part-space operation of heating and cooling of a typical residence. A high-resolution model of a typical 3-occupant residential apartment has been developed using the state-space method and validated by the simulation results from EnergyPlus. The model is then amended to calculate building energy demands with fixed heat and cold supply powers from the perspective of system control, in order to interpret the effectiveness of thermal mass with identical recommended U-value in the HSCW (Hot Summer and Cold Winter) zone in terms of room operative temperatures. It is found that high thermal mass does not help to reduce ideal building loads in the residential buildings in the HSCW zone, but it will improve indoor thermal comfort control in real engineering compared to low thermal mass. Regarding thermal insulation placements of heavy weight external walls under the same thermal mass, it is evidenced that the adoption of internal insulation weakens the thermal mass impact of the heavy weight wall composition compared to that of external insulation. It is inferred that the high thermal mass in the composition of external walls should be exposed to the indoor air to avoid overheating in the cooling conditions. (C) 2019 Elsevier B.V. All rights reserved.