Annual daylight simulations with EvalDRC – Assessing the performance of daylight redirection components

EvalDRC is a newly developed daylight analysis tool for the evaluation of Daylight Redirecting Components (DRC) in architectural spaces. It focuses on the accurate simulation of light redirection with help of the lighting software environment RADIANCE. It employs various key technologies, among them are: a) the daylight coefficient method, b) characterisation of the light redirection behaviour of materials and specially designed systems with appropriate data models, and c) daylight metrics. We present several enhancements to these key technologies and the currently existing tools. In the context of daylight coefficients, we improve the solar contribution calculation by using realistic 0.5◦ solid angle sun primitives, thus generating True Sun coefficients. For simulating light redirection behaviour, we introduce Contribution Photon Mapping, a recent add-on to the RADIANCE environment. In addition, we introduce monthly breakdowns of the established daylight metrics Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE), to provide a more detailed assessment of DRC performance throughout the course of a year. The paper gives an overview of the mentioned annual daylight simulation key technologies. It also explains how our enhancements and developments surpass the current approaches and lead to a versatile tool, capable of producing meaningful and detailed simulation results. A description of the implementation and an application example is given, rounded off by a discussion of the current state of the on-going work and a tentative outlook.