The Impact of Glazing as a Form of Building Envelope on Carbon Emissions in Toronto

<p>In light of the decarbonization targets for Toronto City to mitigate Climate Change and Carbon Emissions by 2030, 2040 and 2050, this study aims to develop an understanding of the real impact of glazing used in buildings' facades on carbon emissions by assessing the whole life carbon (WLC) of a high-rise office building as a case study in downtown Toronto. The objective is to answer the main research question, "What is the impact of different glazing systems as a form of building envelope on total carbon emissions of a high-rise office building in Toronto?" Four types of glazing systems were assessed in One Click LCA for comparing the Embodied Carbon (EC) across multiple scenarios of Window-to-Wall Ratio (WWR) for the office building. They were also modelled in OpenStudio/EnergyPlus for simulating the annual operational energy use and calculating the Operational Carbon (OC) accordingly. The Whole Life Carbon (WLC) of the embodied and operational carbon combined was analyzed in relation to the glazing systems type, WWR, and the thermal transmittance (U-factor) of each system. The results highlighted that embodied and operational carbon are in a direct relationship with the U-factor and WWR for different glazing systems considered. In general, as the WWR or the U-factor reduced, so did the WLC; a reduction ranging from 16% - 40% was addressed from the base case with the highest WLC (47.3 kgCO2e/m2/yr) to the lowest WLC (28.41 kgCO2e/m2/yr), due to the 42% reduction in the Energy Use Intensity (EUI) from (359 kWh/m2) to (207 kWh/m2) by reducing the amount of glazing to 25% and changing the glazing system to a lower U-factor. However, more reductions between 9.4% and 10.8% of WLC could be achieved if the electricity carbon factor gradually decreased in the next 30 years to zero afterward when the electricity is assumed to become clean in 30 years. Finally, the most significant reduction of 17.0% - 41.8% in the WLC is achievable if the building's operations were electrified in 10 years.</p>