Effect of window-to-wall ratio and thermal insulation on building thermal energy in various Iraqi Cities

Abstract

Building design is a key aspect of attaining thermally effective buildings and noticeably
contributes to decarbonizing the environment in hot locations. In this paper, the effect of window-towall ratio (WWR) and thermal insulation thickness on the building energy has been studied
numerically through a validated room model by EnergyPlus. Five WWRs (from 10% to 50% with a
10% increment) are examined under each study location. Later, the influence of various thermal
insulation thicknesses (1, 3, 5, 7, and 9 cm) is investigated at the best WWR in each location
considering the maximum mean temperature reduction and time lag. The study findings indicated that
the best WWR for Al Amarah city is 20%, against 30% and 40% for Baghdad and Erbil cities,
respectively. However, the indoor mean temperature increased slightly as the WWR increased in each
city, influenced by the effect of the opaque elements. As for the effect of thermal insulation thickness,
it could be stated that 3 cm is the best thickness for all locations at the best WWR, achieving maximum
mean temperature reduction and time lag by 1.55 ºC and 3:33 h, 2.01 ºC and 4:03 h, 2.45 ºC and 5:57
h in Al Amarah, Baghdad and Erbil, respectively.