Effects of envelope color and heat insulation on building thermal performance

Abstract

Buildings are large consumers of energy in all countries. In regions with extreme climatic conditions, a substantial share of energy goes to heat or cool the buildings. This heating and air-conditioning load can be reduced through many means; notable among them is the proper design and selection of building envelope and its component. This study evaluates the impacts of envelope color and heat insulation on building thermal performance. Two sets of experiment were conducted in the month of June 2011. In the first experiment, different coating colors was studied, i.e. white, yellow, and brown for types of concrete wall. While, orange, green, and dark brown were applied for roofing tiles in a small-scale prototype. The ambient temperature, surface temperature, solar radiation, wind speed and relative humidity were measured for seven sunny days starting 9.00 am to 7.00 pm. The coating colors that exhibit the lowest surface temperature and heat flux were applied on the three small-scale building models to examine the minimum heat transfer rate into the building. In the second set of experiment, three simulated models were fabricated; no insulation (referral study) and the other two were applied at different location of roof and wall structure, respectively. The heat transfer was computed in order to determine the effectiveness of EPS Geofoam as heat insulator. The total heat reduction between wall insulated and roof insulated models were also compared in order to determine the best placement of thermal insulation in building component. The results showed that white concrete wall exhibits the lowest surface temperature and heat flux at peak hour which recorded at 35.4 °C and 105 W/m2, respectively. On the other hand, the orange roof tile depicts the lowest surface temperature and heat flux at peak hour at 37.4 °C and 3461 W/m2, respectively. In addition, the application of EPS Geofoam demonstrated a remarkable result in reducing the heat transfer into the building. It reduced the internal wall and roof surface temperature by up to 3.0°C and 2.8°C respectively. EPS Geofoam showed the best performance when placed in the roof structure where the total heat flux was reduced by up to 76 percent compared to the control (referral) condition.