Annual and Monthly Trends of Cooling and Heating Degree-Days in Four Different Cities in Iraq as an Index of Energy Consumption

Abstract

Heating and cooling degree days (HDDs/CDDs) method is commonly used to quantify the demand for energy needed for cooling and heating of buildings. Therefore, daily air temperature (minimum and maximum) from four stations in Iraq were analyzed to detect the annual and monthly heating and cooling degree-days trend over the period 1970–2014 using linear regression techniques. The results indicated that; Annual mean values of accumulated heating degree-days AHDDs recorded from 1048oC in Basra station in the south to 2289oC in Mosul station north of Iraq. The annual mean values of ACDDs registered from 2220oC in Rutba to 2927oC in Basra. The annual AHDDs trends analysis indicated significant decreasing trends for all stations with probability level ≥ 99 % except in Basra. The monthly AHDDs showed a general decreasing trend for all stations, and for most months about 91.6 % of monthly trends had negative values. However, the annual total accumulated cooling degree-days ACDDs indicated that all stations registered significant positive trends with probability level ≥ 99 %. The highest annual positive linear tendency rate was recorded in Basra (19.586 oC/year). Moreover, the monthly ACDDs showed in the winter months from December to February, there were no significant trend values recorded. Except for these three months, there were significantly increased ACDDs trends in all stations and for the majority of the months during the study period.