Measuring Up To Global Warming

By Mike Williams & Chris Frankowski

The production and use of energy required to operate buildings constitutes one of Ontario’s largest sources of greenhouse gas (GHG) emissions. Because nearly all newly constructed buildings in Ontario are required to comply with the Ontario Building Code (OBC), adding new provisions to the code is perhaps the most potent means to instigate an effective reduction of GHG emissions in the buildings sector.

In 2012, the OBC made an important addition, which was the requirement to calculate and report not only an estimate of a building’s annual energy consumption but also the GHG emissions associated with the building operations. The method prescribed for calculating the GHG emissions was to multiply the building’s total annual fuel consumption, which in Ontario is predominately natural gas and electricity, by prescribed carbon equivalency (CO2e) factors. The OBC 2012 CO2e factors, expressed in grams of CO2e per kWh of energy, were defined as:

Electricity = 400 g/kWh
Natural gas = 191 g/kWh

Put another way, the OBC was saying that natural gas was twice as clean a fuel source as electricity and, by extension, that building systems fuelled by natural gas should be favoured over electric options when striving to reduce CO2e emissions. This guidance from the OBC appears to contradict the efforts of most other sectors that are making a big push to transition away from fossil fuels to electric options as their primary energy source. This guidance seems further counter intuitive considering the major investments that were made in Ontario to clean up the electricity grid through the retirement of all coal-fired power plants and providing incentives for developing wind and solar farms.

To make sense of the OBC's logic requires an understanding of the power generation facilities that are available for dispatch to meet new electricity demands, such as those created by a new building. In Ontario, available facilities primarily include nuclear plants, hydroelectric dams, natural gas-fired plants, and wind and solar farms. The GHG emissions associated with electricity production at each type of facility varies from CO2e neutral – in the case of nuclear, hydro, wind and solar options – to the relatively CO2e-intensive natural gas-fired plants. The question for a new building, or any new energy load, is how to allocate emissions compared to the allocation for an existing load.

Several accepted GHG accounting methods can be applied when estimating the GHG emissions that should be attributed when a new load is added to a grid. One method, typically referred to as marginal GHG accounting, attributes the CO2e emissions of new loads added to a grid based on the facilities supplying the grid that have the capacity to ramp up and meet this new load.

The sequence by which Ontario's generation facilities are dispatched to meet the demands called for by the grid is complicated. However, for the purposes of understanding marginal GHG accounting, it can be considered that base loads are met primarily by nuclear, hydro, wind and solar facilities and additional loads, or marginal loads, are met by natural gas-fired plants.

Therefore, according to marginal GHG accounting principles, emissions associated with electricity consumption resulting from a new building in Ontario are to be attributed to the burning of natural gas. And, because there is a greater than 50% loss when converting natural gas to electricity, the GHG emissions factor associated with that electricity consumption is more than double what it is when natural gas is used directly as a fuel at a building.

Fast forward from 2012 to the start of 2017 and the introduction of OBC 2017, a new version of the code. OBC 2017 still includes the requirement that operational CO2e emissions be calculated; however, the relationship of the prescribed CO2e factors saw a major change:

Electricity = 50 g/kWh
Natural gas = 191 g/kWh

Per these new factors, electricity is 4 times cleaner than natural gas, marking a complete reversal from the guidance provided in 2012. Although no official document has been issued explaining this change in approach, it appears the OBC has moved from a marginal GHG accounting methodology to an average approach.

An average CO2e emissions factor is calculated by dividing the CO2e emissions associated with the generation of electricity by the amount of electricity produced at all facilities connected to the system, in this case the Ontario electricity grid. Given that the majority of generation facilities in Ontario are considered zero CO2e generation sources, it is no surprise that this change in methods results in an 8-fold decrease in the OBC-prescribed CO2e intensity factor.  The significance of this change is that OBC 2017 heavily favours the choice of electrically fueled systems over natural gas-fired options.

You're not alone if this leaves you wondering, "does the OBC have it right this time?" Considering some of the limitations of both the 2012 and 2017 methods, probably not.

Here are just three limitations that support this conclusion.

  • It does not give consideration to the variability of the CO2e intensity of the electricity grid throughout the day and year.
  • It does not consider future plans for electricity generation facilities (e.g., nuclear plants going offline for refurbishment).
  • It does not acknowledge the growing body of research that suggests currently accepted carbon equivalency factors used to quantify the GHG emissions from natural gas combustion grossly underestimate ancillary GHG emissions that result during the extraction (e.g., fracking) and distribution (e.g., leaky lines) of natural gas.

This third point is perhaps the matter of greatest concern with some research suggesting that we may be under estimating the GHG emissions associated with building operations by a factor of 3.

What should you do?

In the immediate term, designers will be required to follow the guidance of the OBC 2017, which will push the industry toward electrically fueled systems. This represents a shift in thinking in Ontario, where space heating and domestic hot water needs have been met primarily with natural gas-fired solutions. 

In the medium term, we hope to see climate change action plan funding directed toward the development of a set of tools for designers that is sufficiently robust to account for the complexities of Ontario's energy grid, yet simple enough that the calculations can be quickly completed by people who are not subject matter experts.

We encourage readers to download our recent white paper “Measuring Up to Global Warming” for an expanded discussion of all of the concepts in this post.

We also encourage you to connect with the authors of this post and the white paper to further discuss how we can take action together to reduce GHG emissions from buildings and begin to curb the effects of climate change.

Mike Williams
RWDI - Principal

Chris Frankowski
RWDI – Sustainability Consultant