Analyzing Typical Multi-residential Building Unit Layouts in Toronto for Optimization in Circadian Lighting, Human Health/ Wellness, and Daylight Availability

All types of light have the ability to influence the circadian photo entrainment. It is a given that people spend many hours of their waking day indoors, and therefore insufficient lighting levels or improper lighting design, whether that be access to natural daylight or artificial light, can lead to disruption in the circadian cycle. This is especially true if there is unwanted light exposure at night. Recent studies have shown the importance of healthy, occupant-centric lighting in buildings, however urban apartment housing remains an understudied building type. This project analyzed typical units in multi-unit residential buildings (MURB) to determine how unit design parameters including unit geometry and aspect ratio, balcony design, and interior finishes impacted daylight and circadian lighting for residents. The simulation based study compared lighting results from two early-stage design tools: Adaptive Lighting for Alertness (ALFA) which measures Equivalent Melanopic Lux (EML), and ClimateStudio which was used to evaluate daylight autonomy (DA). This study tested if unit configurations met either or all of the lighting criteria for Leadership in Energy and Environmental Design (LEED) standard, WELL Building Standard, and the Toronto Green Standard (TGS). A number of typical layouts for single aspect, 1-bedroom, MURB units were tested in various orientations. Using a base case 1:2 aspect ratio, different unit design parameters were tested including orientation, geometry and aspect ratio, window to wall ratio (WWR), and balcony type. Results of this study showed that even units that seem well lit and would meet LEED, do not necessarily meet TGS or WELL. For example, design options with a 1:2 aspect ratio that have a north and west orientation, cannot achieve the WELL Feature 54 Precondition (circadian lighting design) even with a 100% WWR. Results also compared how different rating systems evaluate daylight and the challenges in the assumptions needed for lighting simulation relating to this housing type. Recommendations for evaluating lighting in MURB are discussed, and a critique of current rating tools in relation to MURB are presented.