A study on the potential of solar irradiation as a source of natural lighting in buildings and its implication on energy-efficiency / Azni Zain Ahmed

A study has been carried out to investigate the potential of using solar irradiation as a source of natural lighting (daylighting) in buildings. Since no daylight data is measured in Malaysia, this work was confined to using direct, diffuse and global solar irradiation data to model illuminance values. Statistical analyses were carried out on 21 years of hourly cloud cover, dry bulb temperature and wind speed to produce Model Year Climate Data. These were used in the subsequent analyses in the study and to determine the characteristics of the Malaysian sky which was identified as an intermediate sky. An artificial sky was built based on this intermediate sky model which was used to conduct illumination distribution experiments on architectural scale models. Three models were tested under the artificial sky to represent a room of simple geometry. Model A had a horizontal window of window-to-floor ratio (WFR) of 10%, Model B had a 10% WFR vertical opening and Model C had a 40% WFR. The daylight factor method was used to predict the hourly interior illuminance distribution. The horizontal window in Model A produced a better distribution across the width of the room as compared to Model B. The illuminance values were integrated into a simple thermal analysis tool to calculate the thermal gains into the room. As much as 44% savings on the consumption of energy could be achieved if a 40% WFR is used instead of 10%. This study has shown that there is potential in energy savings when appropriate daylighting techniques are applied to Malaysian buildings.