Modeling interception of trees’ canopies of indoor daylighting

Developing a methodology of simulating tree shading on daylight performance in indoor spaces such as lux levels on a task plane is investigated. The findings will be useful in improving design of lighting environments in public buildings such as office buildings or classrooms. The method used a camera that takes hemispherical images, positioned in the centre of the task plane. Boundary conditions need to be defined at the outset include the type and age of the trees, the type of the sky and turbidity, the orientation of the window, the time of the day, and the time of the year. The methodology integrated measurement of tree canopy characteristics (gap fraction and Leaf area density) using hemispherical photography and development of 3D objects using parametric modelling to represent tree prototypes. It depended on expressions that predicted gap fractions of a theoretical canopy using a ‘least squares’ technique. The gap fractions results helped to model 2D object (screen) that represents the trees. The illuminance levels were simulated inside the tree-shaded space and the output results were validated against actual measurements in a large physical model using MBE and RMSE techniques (MBE = 0.13, RMSE = 0.02).