Beyond the Kilowatt-Hour: A Multi-Metric Framework for Integrated Assessment of BIPV Systems

The building sector accounts for approximately 37 per cent of global energy-related carbon emissions, and the integration of photovoltaic technology directly into building envelopes has emerged as a significant strategy for decarbonizing the built environment. BIPV, where photovoltaics replaces a primary envelope component contributes to electricity generation, thermal envelope improvement, embodied carbon substitution, and modification of urban surface heat exchange. Current life cycle assessment frameworks, green building certification systems, and national energy codes credit only electricity generation. This thesis argues that this is an understatement of BIPV's total environmental performance advantage and develops a four-metric framework for a better quantification. The framework applies calculation methods with a three-way comparison (BIPV vs BAPV and the conventional envelope), across four case studies. Through the four verified case studies, the framework verifies the research hypothesis, which states that the advantage of BIPV over BAPV in terms of the net environmental performance is underestimated by 34.8%-90.5%, with a mean of 55.2%, mostly due to the lack of the material substitution credit and the thermal performance contribution. The thesis makes multiple original contributions, but primarily a four-metric framework that simultaneously quantifies all environmental functions of BIPV within a single methodology. It’s a first quantification, across a multi-climate and multi-technology sample, of the scale of systematic understatement in single-metric life cycle assessment. It also sets the correct system boundary for BAPV comparisons. Lastly, to the author’s knowledge, no previous published BIPV life cycle assessment (LCA) has used a material substitution credit in a three-way comparison that has found a scenario where the embodied carbon of the BIPV system is lower than the embodied carbon of the conventional system that it is replacing.