Gadi, MohamedAlkelani, Abdulaziz2025-02-192025https://hdl.handle.net/20.500.14154/74895In light of recent revisions to international standards, such as those advocated by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the prioritisation of improved air circulation to support more energy-efficient ventilation systems has become evident. These systems simultaneously enhance occupant satisfaction and thermal comfort. Within this framework, the current research systematically examines the thermal performance and comfort of prefabricated houses in Saudi Arabia, a subject of increasing importance given the rise in summertime temperatures, consistent with the global increase in temperatures. The investigation distinctly outlines the implications of individual components of prefabricated buildings, particularly building envelope components, on the comprehensive thermal performance in the extreme climate conditions prevalent in Saudi Arabia. It ventures to shape innovative prospects in the Saudi prefabricated construction industry, emphasising the reduction of energy expenses while elevating the quality of the indoor environment through the introduction of high-performance prefabricated building components and systems. In Saudi Arabia, characterised by a harsh and hot climate, the residential sector accounts for nearly 50% of national energy consumption. With energy demand expected to rise further, this research investigates the thermal performance and thermal comfort potential of prefabricated housing as a sustainable alternative. The study prioritises optimising building envelope components, developing high-performance precast systems, and providing design guidelines to reduce energy consumption and enhance indoor thermal comfort. It is evident that the study centred its investigation on natural ventilation from the initial stage. Consequently, it revealed a significant reduction in total discomfort hours across various cities in Saudi Arabia. Optimal performance, characterised by minimal total discomfort hours, was observed in cities characterised by lower humidity levels. This suggests that cities with higher relative humidity, exemplified by Jeddah, exhibit extended discomfort hours and encounter challenges in achieving markedly low discomfort hours compared to drier cities like Riyadh, the capital city of Saudi Arabia. The research employs field observations of existing prefabricated houses in Saudi Arabia and simulation tools to evaluate and optimise thermal performance. Findings reveal substantial reductions in total discomfort hours across various zones, with optimisations achieving up to 32% reductions in specific zones. Key innovations include the use of phase change materials (PCMs) with a melting point of 23°C, improved insulation strategies, and optimised window-to-wall ratios, achieving reductions of up to 48% in cooling loads, 99.95% in heating loads, and 51.6% in annual energy consumption for air conditioning. The study culminates in a tangible design product: a high-performance precast system tailored for extreme climates, offering transformative solutions for sustainable construction practices in Saudi Arabia.400enThermal performanceThermal comfortPMVPPDPrefabricated HousingBuilding EnvelopeEnergy efficiencyNatural VentilationHigh-performance building systemsPCMsIEQSimulation-based optimisationPCSPThesis