Understanding home energy efficiency
Where the energy in a Canadian home actually goes, and which upgrades change which part of your bill.
Most advice about saving energy skips the first question: what is your home spending energy on in the first place? Get that right and the upgrade decisions become much simpler.
Where the energy goes
In Canadian homes, keeping the place warm dominates everything else. According to Natural Resources Canada's residential energy data, space heating accounts for roughly 60% of the energy a typical household uses in a year, and water heating for close to another fifth. Lighting, appliances and electronics share what's left, and air conditioning is usually a small slice even in hot summers, because our cooling season is short.
Your own home may differ. A well-insulated new build with a big family will spend proportionally more on hot water; a draughty century home will spend more on heating. But as a rule, if an upgrade doesn't touch heating or hot water, it isn't touching the biggest part of your bill.
What an "energy signature" means
An energy signature is the pattern of how much energy your home uses and when. Plot your monthly gas or electricity use against the outdoor temperature and two things appear:
- A baseline. The energy your home uses regardless of the weather: hot water, lights, appliances, electronics. On a chart it's the flat part during mild months.
- A weather-driven slope. The extra energy used as it gets colder. A steep slope means the house loses heat quickly, which points to insulation, air leaks, windows and doors.
The slope matters because it tells you whether your problem is the building or the equipment. A home with a gentle slope and a high baseline doesn't need new windows; it may need a better water heater or an older fridge retired. A home with a steep slope will keep spending money no matter how efficient the furnace is, because the heat is escaping as fast as it's made.
Time of use: when you use energy
Many Canadian utilities price electricity differently depending on the time of day, with peak, mid-peak and off-peak rates, and the exact hours and prices vary by province and utility. Two households using identical amounts of electricity can pay noticeably different bills if one runs the dishwasher, laundry and EV charger in the expensive window and the other doesn't.
Time-of-use data matters most when you're considering equipment that runs on electricity: heat pumps, electric water heaters, EV chargers and batteries. It changes what the running cost will actually be, and sometimes changes which option makes sense.
Which upgrades affect which part of the bill
- Insulation and air sealing reduce how much heat escapes, so they shrink the weather-driven part of your bill and make rooms feel less draughty. They also let you install smaller, cheaper heating equipment.
- Windows and doors do the same thing, usually at higher cost per unit of heat saved, but they also fix comfort problems like cold spots and condensation.
- Heating and cooling equipment changes the efficiency of turning fuel or electricity into heat. A heat pump moves heat rather than burning fuel to create it, which is why it can deliver more heat energy than the electrical energy it consumes.
- Water heating is the quiet second-largest load. Tank type, temperature setting and whether you own or rent the unit all matter.
- Solar panels don't reduce how much energy your home needs; they produce electricity to offset what you buy. How much they save depends on your roof, your usage pattern and your utility's rules for crediting what you export.
- Batteries mainly shift when you use power, and can provide backup during an outage with the right setup. They rarely pay for themselves on savings alone.
Reading your own bills. Pull twelve months of electricity and gas bills and write down the usage figures, not the dollars. Electricity is measured in kilowatt-hours (kWh) and natural gas in cubic metres (m³) or gigajoules (GJ). Dollars move with rates; usage tells you about your house.
What this means for your next step
Before spending money, it's worth knowing whether your home's issue is the envelope, the equipment or the habits. That's the point of the review we do before recommending anything: your usage over a full year, your time-of-use pattern, and the age and type of what you already have.
Every home is different, and no article can tell you what yours needs. What it can do is help you ask better questions of anyone who quotes you.
Want to see your home's numbers?
A senior energy management consultant will review your energy signature and time of use with you, by phone, at no cost.