A method to estimate the heating and cooling degree-days for different climatic zones of Saudi Arabia

Saudi Arabia’s energy consumption is increasing astronomically. Saudi Building Code prescribes a fixed base temperature of 18.3℃ to estimate the heating degree-days and cooling degree-days. Using historical meteorological data (2005–2014), this article presents the heating degree-days and cooling degree-days estimated for the representative cities in all the five inhabited climatic zones of Saudi Arabia. We used the base temperatures of 14℃, 16℃ and 18℃ for heating degree-days, and 18℃, 20℃, 22℃, 24℃ and 28℃ for cooling degree-days for Dhahran, Guriat, Jeddah, Khamis Mushait and Riyadh cities. We developed multiple regression models for heating degree-days and cooling degree-days at various base temperatures for these zones. Degree-days for other cities in similar climates with limited input data can be computed with these. Lowering of base temperature by 2 K from 18℃ reduced the heating degree-days by 33–65%. At 14℃ of base temperature, the heating requirement reduced by 60–95%. Elevating the base temperature by 2 K from 18℃ lowered the cooling degree-days by 16–38%. At 28℃ of base temperature cooling can be completely eliminated in Khamis Mushait, and reduced by 65–92% in other cities. This observation merits rethinking about use of appropriate base temperatures that properly link the outdoor environment to reduce the energy consumption. Practical application: Using historical data, we developed regression models for predicting heating and cooling degree-days for five cities of Saudi Arabia in various climate zones without the historic data. Using these, we can estimate the changes in heating/cooling load due to the variation in base temperatures. For example, lowering base temperature by 2–4 K from 18℃ reduces the HDDs by 33–95% and elevating the base temperature by 2–4 K from 18℃ lowered the CDDs by 16–68%.