Redefining Climatic Zones Using Temperature and Humidity Metrics for Building Energy Standards: The Case of Saudi Arabia's Climate

Classifying climatic zones is vital for enhancing building energy performance. Global systems, such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers, often overlook regional variations, like Saudi Arabia's humid coastal areas, by relying primarily on precipitation data. This study proposes wet bulb degree days (WBDD) as a key moisture metric, refining Saudi Arabia's climate classification by integrating WBDD with cooling and heating degree days using base temperatures of 17.5°C, 10°C, and 18.3°C, respectively. Weather data from 46 meteorological stations across Saudi Arabia were analyzed to establish boundary conditions for summer, winter, and moisture levels. The findings define five distinct climatic zones: extremely hot and humid, extremely hot and dry, very hot and humid, very hot and dry, and hot and dry, each further divided into nine subzones. The respective representative locations, Jeddah, Riyadh, Al Wajh, Tabuk, and Taif, were identified to guide energy policy and building code revisions. This approach emphasizes the critical role of humidity in energy demand and supports the adoption of WBDD in regional and global climatic classifications. The results enable more accurate building energy modeling, informed code adjustments, and alignment with Building Energy Performance Standards (BEPS), supporting both local and global sustainable development goals. These outcomes will also influence building design in the study area, where climate conditions form the foundation of architectural planning.