A dynamic method for determining the optimal insulation thickness of external walls based on building operation schedules

Setting insulation layers for the envelope is an essential means for building energy saving. How to determine the optimal insulation thickness (X op ) from heat transfer and life cycle cost? The traditional methods are degree-days (DD) and degree-hours (DH), which are only based on outdoor climate and do not take into account building operation schedules. The energy consumption calculated by traditional methods is the same for all buildings, and X op is a constant value that does not vary by building type, which is inconsistent with reality. This paper proposes a dynamic method (degree-hours based on outdoor climate and building operation schedules, DOS). The proposed method was implemented in medical buildings. The results demonstrate that the optimal insulation thickness calculated by the DOS method is different for building types. The X op value of the inpatient building is 63.5 % thicker than that of the outpatient building. There are significant differences between the results obtained by the DOS method and traditional methods. The X op value of outpatient buildings is 28 % lower than that determined by traditional methods, while the X op value of inpatient buildings is 18 % higher. Through comparative analysis, it can be concluded that the DOS method aligns more closely with reality.