For the past three years, I have led an architectural research studio at the University of Toronto’s John H. Daniels Faculty of Architecture, Landscape, and Design that asks: How can we halve the carbon emissions of buildings this decade? Established to expose students, practices, and local policymakers to the methods for measuring upfront and operational emissions, the Ha/f Studio works to catalyze conversations around embodied carbon. Three themes have surfaced across the course’s case studies, each offering clues that broaden our understanding of where immediate, easily achievable reductions can help nudge our collective toward “half.”
Our Buildings Are Icebergs
Across building typologies, foundations, subgrade parking, and basements account for a significant proportion of total embodied emissions. For low-rise residential development, cast-in-place concrete basements exploit a common loophole in Toronto’s zoning coverage allowances that does not limit building depth, ultimately incentivizing subgrade construction of spaces often shored with concrete and insulated with emissive foams. For mid-rise and tall buildings, complex foundation systems and underground parking garages are the product of parking minimums and maximum building heights, two policies that push buildings deeper and deeper into the ground to house cars. Informed by the findings of the Ha/f Studio, Toronto recently removed parking minimums—a simple policy change that will decrease emissions and construction costs through a reduction of total floor area and the length of a project’s construction schedule.
Take Whole Life Carbon Perspective
By plotting the impact of a building over time, we observed the tensions between upfront impact strategies and long-term solutions. Our class first employed a “whole life carbon” approach to assess emissions associated with the construction and performance of a range of façade systems, discovering that the bulk of an enclosure system’s upfront emissions stem from window systems reliant on carbon-intensive framing materials, such as aluminum or polyvinyl chloride. Last fall, we scaled our investigations up to the whole building, finding that the actual operational data uniformly eclipsed modeled emissions, and that the balance between embodied and operational emissions varied significantly across the campus’s buildings.
Geography Really Matters
Life cycle assessments rely on manufacturer-provided environmental product declarations outlining the full range of ecological impacts that the sourcing, processing, and manufacturing of its materials and products embody. The location of a factory is a key driver of emissions due to varying power grid intensity across North America. Similarly, as we electrify our building systems, a key driver of emissions will be a combination of climate and local grid intensity. The crossover point between embodied and operational carbon varies significantly across North America. The argument for additional layers of glazing and insulation is strong in cold-climate, dirty grids and almost nonexistent in green grids. Decarbonization of our grids serves to push the crossover dates further out, placing even greater importance on limiting upfront emissions.
The Ha/f Studio’s findings underpin ongoing work with Toronto to engage the industry in producing a regional benchmarking study and establishing embodied carbon policy to guide reductions. Given the geographical nature of emissions, we would benefit greatly from some version of the Ha/f Studio taught across the continent—serving to catalyze the types of conversations we’re having in Ontario.
This article first appeared in the April 2023 issue of ARCHITECT.
Read more on building a greener world: The Race to Decarbonize Buildings Is On. | Building on the Best of COP27. | Carbon intelligence for reuse decisions. | Architecture had a critical role at COP27.
