Heat transfer analysis of vertical shading device in office buildings in Malaysia using computer simulation

Abstract

The architectural trends of glazed facades have brought more daylighting and transparency into buildings. Large glazed areas bring a large amount of solar radiation, which can be wisely utilized for better environmental building design. However, glazed envelopes can cause excessive heat inside the building, where potential sources of unwanted overheating and glared effects cause indoor discomfort to the building occupants. Therefore, shading devices are designed to prevent excessive solar radiation and to distribute daylight evenly into the interior spaces. Meanwhile, shading devices are based on more of aesthetic value for the building façade. In the design of the shading system, there are a variety of consideration related to the shading type, such as material properties and many more. In order to enhance the daylighting performance, the shading device should play a more efficient role in order to control the heat inside the building. Therefore, a study was conducted on heat gains, particularly for vertical shading device in an office building using computer simulation. The study used ‘ECOTECT’ software to perform passive heat gains breakdown calculation. ‘ECOTECT’ has been used to calculate the distribution of daylighting needed for interior spaces in the building. A field measurement was conducted to find out the heat gains in the office building. The temperature was recorded by using data logger. The experiment tested related variables such as the distance between the shading device and the glazing area, as well as materials and thicknesses of the shading device. The data was collected and used to calculate the heat gains in the office building. This data justified the simulation result that compared the heat gains before and after the test variables was conducted. The investigation found that the concrete vertical shading device with 150mm gaps from window had better reduction capacity of heat gains into building. In addition, the analysis also found that with 150mm thicknesses of a vertical shading device has a lower rate of heat transfer whereas, the heat gains in the building was reduced from 31.2W/m2 to 29.9W/m2 . This result is compatible with recommended value that is below 50W/m2 and in accordance to Malaysian Standard 1525:2007. The study, therefore, proposes that these criteria should be taken into consideration in the pre-design phase of an office building in order to apply appropriate shading device in avoiding unnecessary heat transfer into the office building.