Arid and hot regions, like Saudi Arabia, utilize up to 60% of the country’s energy to regulate 
buildings’ indoor comfort. Energy efficiency is a long-term sustainability measure that is part of the 
government’s Vision 2030 strategy. A standard method of improving the thermal performance of 
buildings is through the use of insulation materials. Considering the cooling loads’ requirement and 
the Global Warming Potential (GWP), the present research evaluated the effectiveness of insulation 
materials, including extruded polystyrene, expanded polystyrene, rock wool, and glass wool in 
the hot, arid climate. For this case study, four similar villas facing the cardinal directions were 
selected from the residential project at Qassim University. HOBO data loggers were used to collect 
indoor temperature data. Thermal performance and Life Cycle Assessment (LCA) were conducted in 
accordance with Saudi Building Code-602 (SBC-602). Simulation outputs based on the four cardinal 
directions were used for assessing the thermal performance and LCA of the different thicknesses and 
densities of insulation materials. This was done using IESVE and SimaPro, IMPACR2002+, to assess 
their cooling load and GWP, respectively. The results suggest the potential for using lower insulation 
thickness for the northern and western façades without violating the SBC. The results obtained the 
actual thicknesses of the three insulation materials for achieving indoor temperatures in the four 
cardinal directions and the selection of materials and their densities along with associated GWP. The 
outputs of the study have been generalized in the form of a performance-based flowchart as a tool for 
selecting the type and thickness of thermal and environmental insulation in residential buildings in 
the Qassim region of Saudi Arabia.