Buildings
Building emissions decreased by 0.6% in 2023, which was largely attributed to a mild winter that translated to lower overall demand for natural gas space heating.
Buildings remain the highest-emitting sector in Halton, Toronto, and Peel. Per capita building emissions range from a low of 2.4 tCO2eq/person in Durham to a high of 5.2 tCO2eq/person in Hamilton.
Building emissions come from two sources: from natural gas combustion onsite for space and water heating, and those associated with the electricity consumed in a building. Natural gas used for space and water heating generates roughly 85% of total building emissions. In 2023, natural gas emissions declined 4.7% across the GTHA, but upon normalizing the data to remove the impact of weather, that decline becomes 1.6%. Electricity emissions on the other hand rose 30% because of the increasing carbon intensity of the provincial electricity grid.
As our region continues to grow, building retrofits and deep energy efficiency improvements are needed to achieve and sustain significant annual emissions reductions.
TAF’s analysis of 1,620 buildings from Ontario’s Energy and Water Reporting and Benchmarking (ERWB) datasets found the average weather normalized energy use intensity of the province’s biggest buildings dropped nearly 4% between 2019 and 2022. While this indicates energy efficiency improvements are having an impact, the rate of these improvements must accelerate substantially to meet climate goals. In 2022, the average energy use intensity was 246 ekWh/m2 in multi-family residential buildings and 269 ekWh/m2 in office buildings.
Scope 3 Embodied Carbon: Together, production of concrete and steel are responsible for nearly half of total embodied carbon emissions in buildings. A TAF-funded study benchmarked the embodied emissions of building materials, reporting that the average annual embodied emissions of all new low-rise homes built in the GTHA is 0.84 MtCO2eq. Another TAF-funded study showed that high-rise building materials account for 465 kgCO2eq/m2, totaling 1.6 MtCO2eq annually in the GTHA. Adding these two sectors together means that the GTHA’s total embodied emissions in new buildings are at least 2.5 MtCO2eq.
Since 2020, TAF has noticed discrepancies in electricity generation from natural gas combustion reported by IESO and NIR. The table below illustrates the electricity emission factors and differences between these two sources by year. Notably, in 2022, IESO reported 40% more electricity generation from natural gas compared to what the NIR reported, resulting in a 32% increase in emissions. IESO’s data is based on settlement purposes, while the NIR uses information from StatsCan’s facility owner survey. TAF uses IESO electricity generation data in the inventory and will continue to monitor differences as the 2023 NIR report is released.
2020 | 2021 | 2022 | |
|---|---|---|---|
IESO | 36 | 44 | 51 |
NIR | 33 | 36 | 38 |
Difference | 9% | 23% | 32% |
Natural Gas
“Natural gas,” also known as methane or fossil gas, is largely consumed onsite for space and water heating and continues to be the major contributor to building emissions. Natural gas emissions decreased by 4.7% in 2023, reaching 20.9 MtCO2eq. When normalized to account for weather variability, however, emissions decreased by only 1.6%. This indicates that much of the reduction in natural gas emissions observed in 2023 was attributable to a milder winter. Broken down by customer class, the residential sector saw a 2.8% decrease in weather normalized gas emissions, followed by industrial (down 0.6%) and commercial (down 0.4%).
Normalized for weather and population, natural gas emissions decreased by 4.6% across the GTHA, from 2.94 to 2.80 tCO2eq per person.
Durham has the lowest per capita weather normalized gas emissions (2.1 tCO2eq/person) while Hamilton has the highest (4.7 tCO2eq/person).
TAF reports on Scope 3 fugitive methane that leaks from extraction, fracking, pipelines, and distribution, the full life cycle of natural gas. Including fugitive methane demonstrates that natural gas combustion emissions are 30% higher than typically reported. Ignoring this important source of upstream emissions can undermine climate action priorities, particularly where natural gas is marketed as a “clean” fuel source.
Electricity
Electricity emissions have steadily increased since 2019, rising from 1.7 MtCO2eq to 3.9 MtCO2eq over that span. In 2023 alone, emissions rose by a staggering 30% and are now the highest since 2015, when the last of the province’s coal-fired units were still being phased out.
GTHA electricity emissions are influenced by two primary factors: overall electricity demand in the region and the carbon intensity of the provincial grid used to meet that demand.
While electricity demand in the region actually decreased by 0.7% in 2023, from 58.8 to 58.3 TWh, the carbon intensity of the electricity grid increased by 30%. This is a direct consequence of the province’s increasing reliance on gas-fired electricity generation, which is forecast to continue to increase over the next 10 years and partially offset carbon reductions realized through electrification of other sectors.
This year, we are showing the forecasted Ontario electricity grid emissions using low and high emissions scenarios representing a range of possible pathways. The Low Emissions Scenario is based on the high nuclear case from IESO’s 2024 Annual Planning Outlook, and the High Emissions Scenario is derived from the IESO’s 2025 projected demand, assuming 25% of the demand-supply gap is met with natural gas.
Recent TAF analysis found that an increased reliance on gas-fired electricity generation has offset much of the carbon reductions from efficiency improvements in the building sector.
To address this problem, it is imperative to prohibit any new or expanded gas-fired electricity generation capacity and limit how often our existing gas plants are operated, scale energy efficiency and conservation efforts to reduce energy waste, scale up load flexibility to increase utilization of existing grid infrastructure, and invest in new local and utility-scale clean generation, including distributed solar and storage in transmission-constrained urban areas.