Dissertation Defence: An occupant-centric design framework for healthy and energy-efficient multi-unit residential buildings; life-cycle thinking approach

Hetti Ishanka Perera, supervised by Dr. Kasun Hewage, will defend their dissertation titled “An occupant-centric design framework for healthy and energy-efficient multi-unit residential buildings; life-cycle thinking approach” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering.

An abstract for Hetti Ishanka Perera’s dissertation is included below.

Examinations are open to all members of the campus community as well as the general public. Please email kasun.hewage@ubc.ca to receive the Zoom link for this exam.

Abstract

The sustainable building construction industry has increasingly focused on reducing operational energy use and carbon emissions through performance-based codes and mandates. While this approach is critical for climate change mitigation, it often neglects occupant-centred performance in multi-unit residential buildings (MURBs). Individual housing units can exhibit significant variation in indoor environmental quality, energy demand, and occupant health outcomes. Reliance on whole-building averages in energy codes, simulations, and policy benchmarks may obscure unit-level performance differences. These arise from factors such as orientation, floor level, envelope exposure, shared internal surfaces, solar access, and material-related emissions. This thesis addresses the above gap by developing a housing-unit-level decision support framework for selecting occupant-centric, energy-efficient, new-construction MURB design pathways. A case study of a low-rise MURB in British Columbia was analyzed using a multi-phase simulation and life-cycle assessment methodology. Initially, energy and long-term thermal comfort performance were evaluated, with an annual thermal discomfort metric introduced as a performance indicator. Then, a parametric optimization was conducted to identify unit-specific envelope and operational strategies that reduce energy consumption while enhancing thermal comfort. Daylight and visual comfort were assessed through parametric façade analysis using spatial daylight autonomy, useful daylight illuminance, annual sunlight exposure, and glare autonomy. Subsequently, a dynamic life-cycle assessment framework was established to integrate embodied impacts, operational energy-related impacts, outdoor air pollution, and near-field indoor chemical emissions-based human health damage. The unit-level human health damage metric was quantified in disability-adjusted life years. The final phase synthesized these outputs into the Unit-Level Performance Compass (UPC), a multi-dimensional framework for scoring, ranking, labelling, and visualizing housing-unit-level performance. The proposed UPC framework addresses the limitations of whole-building average assessment by translating unit-level energy, thermal comfort, daylight, environmental impact, and health-related outcomes into a transparent structure. This enables stakeholders to identify high and low-performing units, compare design trade-offs more clearly, and select early-stage design strategies that improve both energy performance and occupant-centred outcomes in future MURB design.