On a January night in Ontario, millions of furnaces switch on at once. Most of them burn natural gas, piped in from Western Canada or the United States. Heating, cooling and lighting buildings produced about 12 percent of Canada's greenhouse gas emissions in 2024 (Environment and Climate Change Canada), and cars and trucks added much more (Lesson 4). Every community makes energy decisions: how its buildings are built, how its streets are laid out, where its electricity comes from. Some of those decisions are made by governments, some by companies and some by you. This lesson looks at how those decisions add up.
Where a community's energy comes from
Ontario's electricity is mostly low-emission, from nuclear, hydro, wind and solar, since the province closed its last coal-fired plant in 2014 (see Energy in Unit 3). But electricity is only part of the picture. Most Ontario homes are heated with natural gas, and most vehicles run on gasoline or diesel. That is why a key strategy for cutting a community's emissions is electrification: switching heating and transportation from burning fuels to running on clean electricity, while making buildings use less energy in the first place. The catch is that more electric heating and vehicles mean the grid must grow, and decisions about how to supply that extra power (more nuclear, more gas, more renewables and storage) are debated.
Three kinds of decision-makers
| Decision-maker | Examples of energy decisions | Effect on the community |
|---|---|---|
| Governments (federal, provincial, municipal) | Building codes that set insulation and efficiency standards; Ontario's coal phase-out (completed 2014); Toronto Green Standard for new buildings (since 2010); rebates for heat pumps and insulation; zoning that allows denser, walkable neighbourhoods | Set the rules and incentives that shape millions of other decisions for decades |
| Corporations and utilities | Building efficient warehouses and offices; buying renewable power; switching delivery fleets to electric vehicles; utilities building transmission lines, storage or new power plants | Large single decisions with big effects on emissions, energy prices and jobs |
| Individuals and households | Thermostat settings; adding insulation; choosing a heat pump, an electric car or transit; where to live and how far to commute | Small choices that add up, and that depend on income, housing type and what options are available |
Heat pumps and efficient buildings
A heat pump works like a refrigerator running in reverse: instead of making heat by burning fuel, it uses electricity to move heat from the outside air (or the ground) into the house, even on cold days. Because it moves heat rather than making it, a heat pump typically delivers two to three units of heat for every unit of electricity it uses over a season, and in summer it runs backward as an air conditioner. Modern cold-climate models keep working in temperatures far below freezing, though very cold snaps may need backup heat. The other half of the story is the building envelope: walls, roofs, windows and air sealing. A well-insulated, airtight building needs much less energy no matter how it is heated, which is why building codes and green standards focus on it.
Energy at the community scale
- District energy: one central plant heats or cools many buildings through underground pipes. Toronto's Deep Lake Water Cooling system, run by Enwave since 2004, draws water at about 4 °C from deep in Lake Ontario to cool downtown office towers, using far less electricity than conventional air conditioning; much of that water then continues into the city's drinking-water supply.
- Oujé-Bougoumou, a Cree village in northern Québec built in the early 1990s and designed by the community with architect Douglas Cardinal, heats its homes and buildings with a district heating system fuelled by waste wood from a sawmill.
- Community-owned renewables: First Nations in Ontario own or co-own wind, solar, hydro and battery projects (Unit 3), keeping energy revenue in the community.
- Replacing diesel in remote communities: many remote First Nations have relied on diesel generators, with fuel flown or trucked in on winter roads; Wataynikaneyap Power, a transmission company 51 percent owned by 24 First Nations, has connected a dozen or more remote northwestern Ontario First Nations to the provincial grid since 2018; construction of its transmission system was finished in December 2024.
- Compact, mixed-use design: shorter trips, shared walls in townhouses and apartments, and district energy all work best when buildings are close together (Lesson 2).