Why electrify your home?

(Part 1) By Dan Vivian and Cecile Wilson

[Atmospheric CO² near Mauna Loa, Hawaii on May 19: 422.39]

Reducing greenhouse gas (GHG) emissions and lowering heating costs are two reasons why people are electrifying their homes. By combining a heat pump with solar power, you can have heating that is both cleaner and less expensive than using natural gas.

In this article, we provide the rationale for reducing the GHG output and compare the emissions produced by various home heating methods. In the August edition, we will show how using the combination of an electric heat pump and solar power can also save you money.

Why are we concerned about fossil fuels and GHGs?

Data collected by scientists around the world indicate that burning fossil fuels (coal, oil, and natural gases) has emitted so many GHGs that they are in the process of changing the makeup of the atmosphere. This change is enough to cause a significant rise in global temperatures around the earth.

There are all sorts of consequences to these rising temperatures. The delicate balance of the climate is disrupted, resulting in droughts in some parts of the world, floods in others, fires, hurricanes, typhoons, tornadoes, melting polar ice caps, rising ocean levels, stress for plants and animals and even extinctions. We can expect a whole list of related issues for human beings and our social institutions as well.

Even if we (governments, corporations and financial institutions included) decide that we need to keep burning fossil fuels despite their destructive effects, there are limited fossil fuels available. As we use more, sources become depleted and harder to find and access, which makes them more expensive. We need to transition away from fossil fuels eventually – why not make the move to cleaner heating sources sooner, while we have more control over the transition?

How do fossil fuels compare to other heat sources?

The graph below compares the GHG emissions produced by the various means of heating space and water in Ontario. Natural gas burned at a high efficiency (92 per cent combustion, which is common for condensing furnaces and boilers) is used as the base rate for GHG emissions and is given a value of one. A value higher than one indicates that the heat source emits more GHGs than gas burned at 92 per cent efficiency; a value lower than one indicates that the heat source emits fewer GHGs.

In addition to a high-efficiency furnace, this graph shows the emissions produced by gas burned in a conventional efficiency heating appliance (about 82 per cent efficient). This is indicated as ‘Natural Gas Conv’ on the graph.

Note that fuel oil (78 per cent efficient, which is typical) emits about 75 per cent more GHGs than high efficiency gas, propane about 25 per cent more and conventional gas about 12 per cent more. In Ontario, conventional electric heat produces about 90 per cent fewer GHGs than high efficiency gas does, while an electric heat pump produces about 96 per cent fewer GHGs (or about 10 per cent and four per cent respectively of the GHGs emitted by high efficiency gas). The GHGs produced by solar power is so tiny (one divided by over 1 million) that it is effectively zero.

How significant is home heating?

The City of Ottawa tracks its GHG emissions from buildings, transportation, waste, agriculture and its own operations. Buildings are further subdivided into two subsectors: residential and industrial/commercial/institutional. In 2020, buildings were the largest source of GHGs in Ottawa at 46 per cent of total emissions, with the two building subsectors being about equal (see Results of the 2020 Community and Corporate Greenhouse Gas (GHG) Inventories, September 2021, City of Ottawa publication for more information). On a more personal scale, a 2,000-square-foot house typically accounts for between 4.8 and six tonnes of GHG emissions per year.

In 2020, 83 per cent of building emissions came from natural gas. Even though natural gas is often touted as a ‘clean’ fuel, the chart below shows clearly that moving from any fossil fuel (including natural gas) to an electric heat pump would significantly lower GHGs.

In the August, we’ll demonstrate how combining a heat pump with net-metered solar panels can save you money as well.

Dan Vivian is a mechanical engineer and the principal for Building Science Trust Inc., as well as a Climate Reality Leader (2018). He helps people move their buildings to net zero energy consumption. Cecile Wilson is a resident of the Glebe and is interested in climate change, the actions we can take to mitigate it and the discourse surrounding this critical topic.

Graph courtesy of Building Science Trust Inc.