Abstract 200 words
Abstract 200 words
This research investigates factors affecting the prediction of daylight availability in existing high-rise residential buildings located in high-density environments in order to develop a simplified daylight prediction method. To achieve this, several stages were completed. First, the daylight availability at an unobstructed area was evaluated, which involved collecting daylight data for a one-year period at the University of Hong Kong daylight station. Second, RADIANCE sky models were validated, based on scale model measurements and simulation results, to ensure their validity in modelling the local sky. Stage three was the investigation of factors affecting daylight prediction in high-rise residential buildings. Nineteen housing models representing eight plan types of existing residential buildings were selected. The Visible Sky Area (VSA), Vertical Sky Component (VSC) and Vertical Daylight Factor (VDF) were calculated for these buildings. VSC was used for defining the minimum VSA for Hong Kong. The final stage involved developing and validating a new daylight prediction method. Nine simple regression models and one multiple regression model were developed using statistical analyses based on the relation between the VDF and the VSA for different combinations of ground and building reflectances. All models were validated with RADIANCE using six hypothetical building layouts. To calculate the VSA, a calculation tool was constructed. The study found that the two most influential factors affecting the prediction of daylight availability on the window plane are the VSA and the surface reflectances. The VSA is affected by building forms and external obstructions. Most private housing estates have poor VSA’s, resulting in poor VDF performances. For each combination of ground and building reflectances, a very good correlation between VSA and VDF was found. The validation of the new method showed that some models accurately predicted the VDF, while others were less accurate. This study proposes three regression models together with a VSA calculation tool as a new daylight prediction method called the VSA Method for the Hong Kong Context.