Modification of Walls’ Thermal Resistance Value in the Saudi Building Code According to a Comprehensive Green Assessment

Mostadam is the Green Building Rating System in the Kingdom of Saudi Arabia. Indoor thermal comfort assessment is one of the key issues in Mostadam. Controlling the thermal characteristics of the building envelope is one of the main methods to achieve thermal comfort. In Mostadam, these characteristics should comply with the Saudi Building Code for energy conservation, where the required thermal resistance value (R-value) of the above-grade walls for twelve thermal zones are unified despite their various climatic aspects. Taif city, for example, has a moderate temperature for most of the year in contrast to many Saudi cities that share the walls’ R-value. The purpose of this paper is to highlight the importance of considering a comprehensive assessment of a building across all its life stages before judging any green practice. Therefore, a simulation methodology was used for a set of models through which the impact of R-value on the building’s assessment to its different stages can be checked. Simulation results showed that half the value of the required Saudi code’s R-value can give the same thermal target in Taif city. But the higher R-value means more materials and loads, which accordingly leads to more construction costs. To decide that a conservation method is appropriate, it should be judged over the whole life cycle of the building. Thus, it is not considered appropriate if a thermal solution gives the same energy consumption during the operational building stage but more cost during the construction and demolition stages. The manuscript results in that the suitable R-value that should be used within the Saudi codes and, therefore, Mostadam for the above-grade walls in Taif city is 1 (m2 K)/W, as it maintained the targeted thermal comfort achievement with less building construction cost. It is recommended to evaluate the Saudi code values accordingly.