An assessment of the Saudi Residential Buildings Envelope Code under the current and future climate change scenarios: the case for Jeddah in the hot and humid climate region

Due to the severity of the hot climate in the Kingdom of Saudi Arabia (KSA) that necessitates the high demand of air conditioning for cooling, the residential building sector among other building types represents more than 44% of the total electricity consumed in the country, partly due to Saudi's rapid population growth, which is at present 33.7 million and expanding at an annual rate of 2.5%. In light of this issue, various researchers have shown that implementing an energy code and standard can perform a significant role in improving energy efficiency in the building sector. This encouraged the government to establish a new mandatory Saudi Residential Buildings' Envelope Code (SRBEC) to reduce energy consumption. However, there are two barriers to the successful implementation of the code. Firstly, the SRBEC was regulated without considering the readiness of the construction industry to apply this code as well as there being no consolidation between the code and construction techniques and materials currently used in the construction industry in KSA. Secondly, another drawback was the lack of serious consideration in terms of climate change in the future when creating the code. It was established that climate change predicted for the future was completely disregarded. This research aims at studying the application of the requirement of the mandatory three versions of SRBEC to the existing single-family houses (villas) as the main dominant residential building type in Jeddah, KSA by means of feasible building construction methods currently available in the market. The research also aims at evaluating the energy performance of the existing air-conditioned villas and the newly built villas to the mandatory standard of SRBEC under the current climate condition and the future climate change scenarios. Based on real on-site measurements carried out for each of the three selected villas, two validation techniques were employed in order to validate the thermal performance of the actual villas against the simulated models. Firstly, while the buildings were free-running hourly temperature calibrations between the DesignBuilder model and the actual interior temperature were conducted by comparing the indoor temperature resulted from the simulations against the actual temperature recorded by data loggers at hourly intervals. Secondly, during the three summer months that have the hottest weather in which the highest electricity consumption is existed, the simulated energy consumptions for each villa were calculated and compared with the billed electricity consumptions. Current and future weather data files for the periods (current, 2050s and 2080s) also Greenhouse Gases (GHG) emission scenarios the A2, A1B, and B1 for Jeddah city were obtained from the climate generator software Meteonorm. This research created different scenarios of constructional compositions for buildings fabrics including walls, roofs, floors and windows in order to fulfil the requirements specified in the three versions of SRBEC (code1, code2 and code3). These compositions designs were created and developed on the basis of appropriate selections of local and real construction materials by referring to the construction market survey in the KSA. In addition, a long-term financial study was conducted by considering the prediction of different electricity prices scenarios in the future to analyse the economic feasibility of applying the SRBEC to the three selected case studies villas under the current and future climate change periods. A parametric analysis approach on the three base cases models of the selected villas was adopted to improve the capability of the wall insulation, roof insulations and the Solar Heat Gain Coefficient (SHGC) of window glazing taking into consideration the requirements listed in the SRBEC in order to reduce the cooling energy consumption. Finally, the research examined the applicability of utilising the cladding system currently being used for decoration purposes to be used as shading treatment for the opaque external walls of the building in order to reduce the cooling energy consumption. The research outcomes identified suitable and feasible construction materials and techniques for enabling the application of the SRBEC to typical villas in KSA. The research outcomes ensure the applicability of the SRBEC by feasible and locally available construction materials and techniques that were created, developed and introduced by this research to the construction industry (governmental authorities, contractors and buildings' owners). The results also showed that by complying with the SRBEC, it is possible to achieve electricity savings of 38%-40% for villa A, and 16%-20% for both villas B and C. Furthermore, the assessment results confirm that despite the increase caused by climate change, the application of the SRBEC to the existing villas can enable them to nullify and combat the effects of the future climate changes within the time slices 2050s and 2080s. The financial feasibility results demonstrate that despite the difference in the payback period, the application of requirements of the SRBEC to all the three villas would be economically feasible with all predicted future electricity prices (constant, growing and decreasing). Finally, all the attempts to improve the performance of the SRBEC under the current and future climate change by studying feasible local passive design strategies were not applicable to achieve valuable improvement results.