Toronto Becomes First Jurisdiction in North America to Enact Whole-building Embodied Carbon Caps on New City-owned Buildings

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Mantle Developments

On May 10, 2023, Toronto became the first North American jurisdiction to require lower-carbon construction materials, limiting embodied carbon from new municipal building construction.

New City-owned buildings must now limit upfront embodied emission intensity — emissions associated with manufacturing, transporting, and constructing major structural and envelope systems — to below 350 kg CO2e/m2. This requirement is now a tier 2 (optional) requirement in the Toronto Green Standard (TGS) v4 for non-city buildings. Private developers should consider themselves on notice since, typically, tier 2 measures become tier 1 (mandatory) requirements a few years later when the next version of the TGS comes into effect and tiers shift downwards. TGS v5 is scheduled to be implemented in 2025; Council has already asked for more information on the feasibility of applying mandatory embodied carbon caps more broadly.

City Council approved the proposal to update the embodied carbon requirements in the currently active TGS v4. This was brought forward by the City’s planning department and previously approved by the Planning and Housing Committee on April 27, 2023. This update makes Toronto the first jurisdiction in North America to set whole-building embodied carbon caps on new city-owned buildings. Mantle Developments is proud to have co-led the benchmarking study performed in 2022, which supported the creation of these new caps in partnership with Ha/f Studio.

The new embodied carbon caps apply to new City-owned buildings and optionally to private new buildings that are mid to high-rise residential & non-residential if applying for voluntary higher levels of performance. The caps apply to the pre-occupancy upfront embodied carbon emissions from life cycle stages A1-A5.

  • A1: Raw Material Supply
  • A2: Transport (of Raw Materials to Manufacturer)
  • A3: Manufacturing
  • A4: Transport (of manufactured goods to construction site)
  • A5: Construction/installation processes

These upfront embodied emissions are responsible for the vast majority of a building’s embodied emissions (typically > 75%). Since they happen pre-occupancy, they are fully manageable through lower carbon decisions in design, procurement, and construction. Substantial industry consultations have shown that low-carbon materials are readily available in the Toronto market with zero to marginal impact on cost or schedule. Industry leaders have noted experience of around 30% embodied carbon reductions are easily achievable without major changes to design or primary structural material.

Post-occupancy embodied emissions associated with the use phase (B) and the end-of-life phase (C) – although essential to manage long term – are a minor source of embodied emissions, are spread over many decades, and involve much uncertainty since future assumptions are required. As such, the new caps will only apply to upfront embodied emissions to ensure reductions occur in the short term and don’t rely on future assumptions that may not be accurate.

The caps are currently limited to major structure and envelope materials. Future policy updates may expand the scope, applying to more life cycle phases and materials/systems. However, the current targeted approach, although not perfect, represents a sensible first step in effectively shifting the industry to holistic embodied carbon management and reduction.

Previously, TGS v4 had two levels of embodied carbon management (both voluntary for private buildings). The first level required disclosure of upfront emissions (A1-A5) without any performance caps. The second level required a 20% reduction against a baseline building for total cradle-to-grave emissions (A1-A5, B1-B5, C1-C4). New City-owned buildings were required to disclose their upfront carbon, with the 20% reduction against a baseline being optional for higher-performing City buildings.

The new updates replace these requirements by consistently focusing on upfront embodied emissions (A1-A5) for both levels and setting intensity caps of 350 kg CO2e/m2 and 250 kg CO2e/m2 for the two levels. This moves away from the “% reduction against a baseline” approach; this simplifies compliance by avoiding the need to create a baseline building and removes the possibility of “gaming the system” by setting an artificially bad-performing baseline. These new caps align with the Canada Green Building Council (CAGBC) Zero Carbon Building Standard v3 innovation levels.

As part of the 2022 study that Mantle Developments co-led to benchmark embodied carbon of large (“Part 3”) buildings in Ontario, we also worked with two City of Toronto-owned projects at the late stage of design to calculate the projects’ embodied carbon and offer some easy-to-implement material substitutions that could reduce it. This study found one of the projects was already below the new embodied carbon cap of 350 kg CO2e/m2, showing this level of performance is already possible. Our team identified several easy-to-implement material substitutions with negligible impact on cost and schedule, which would further reduce the embodied carbon intensity by an additional 26%. The project team adopted the substitutions resulting in over 800 tonnes of avoided embodied carbon!

It should be stressed that the updated mandatory TGS v4 tier 1 still has no embodied carbon requirements for private construction. Only private projects aiming for the voluntary higher levels of TGS performance (tier 2 or tier 3) are subject to these new caps. It should also be stressed, however, that when the next version of the TGS (v5) comes into effect, it may include a broader application of mandatory embodied carbon caps.  Developers and construction material manufacturers would be wise to expect similar mandatory low-carbon design and materials requirements on private buildings soon. Developers take note: the time is now to develop a low-carbon materials strategy and inform your design and procurement teams that lower embodied carbon is a priority.

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