Supporting evidence-based design using lighting simulations : A framework for lighting simulation of visual comfort in building design

Abstract: This research aims to integrate lighting simulation into the evidence-based design process for achieving improved lighting outcomes in built environments with a particular emphasis on visual comfort analysis in office settings. The objectives of the study include 1) understanding the current usage of lighting simulation tools, learning designers’ experiences' and needs, 2) providing a conceptual framework to integrate the use of lighting simulation in the evidence-based design (EBD) process, 3) testing the usage of the conceptual framework (named EBD-SIM) through two field studies.First, the lighting simulation tools were reviewed from multiple perspectives reflecting their current state in terms of main characteristics and applications. The usage of lighting simulation tools was investigated by conducting an online survey among lighting designers in 2014. The results showed that lighting simulation programs were widely used in Sweden, with DIALux being the most popular. The most calculated metrics were interior illuminance, glare indexes, and daylight factors. Ease of use and simulation speed were the most important factors in selecting these tools (Paper I). The changes and developments in the usage of lighting simulation tools over five years were investigated by conducting the second survey in 2019. The comparison between the two surveys revealed that DIALux remained the most popular tool though its usage slightly dropped,and the usage of Radiance-based programs was improved. In both surveys, illuminancewas the most frequently calculated metric for both daylight and electric light.In the second part of this thesis, the integration of simulation tools in the Evidence-Based Design (EBD) process was explored, leading to the development of an integrated conceptual framework, named EBD-SIM (Paper II). The application of the EBD-SIM framework with a focus on the post-occupancy evaluation (POE) step was tested with two field studies in an existing office building in Sweden (Paper III & Paper IV). Occupant visual comfort was investigated using holistic objective-subjective evaluation with different sample sizes (N=15, N=45), different times of the year (October and June), and two groups of occupants (within-subject and between-subject study). Both studies confirmed that point-in-time illuminance had the highest correlation with perceived visual comfort by occupants. The study in June showed that annual daylight performance metrics also had some degree of correlation with occupant satisfaction. It also revealed that, at least for the variables related to daylight, a POE study needs to be conducted at different times of the year to obtain a more comprehensive picture of the user perception of the lit environment. Using simulation tools also in the POE step of EBD has several advantages. The calculated performance metrics give an overview of the lit environment's objective characteristics, making it possible to document them and provide more explicit evidence for further investigation. In addition, the simulated model can be used further to generate other performance metrics should it become necessary based on further evidence.