Everyone knows that thermostat set back can save on energy costs. So, how much should you set it back by? It’s not as easy as you might think.
When you turn back your thermostat you have an opportunity to reduce your energy costs. However, when you set it back too much, your furnace has to work harder to get the heat back up to temperature and may offset savings, especially if your house is not air-tight or well insulated. Of course, this is amplified by the length of time you have the thermostat set back for too. For example, should you set it back by a different amount if you’re away for the day at work versus out for the evening for dinner and a movie.
CMHC states that” “a drop of 2°C (3.6°F) will lead to some savings and little risk. Some householders reduce temperatures 4°C to 6°C (7°F to 11°F). However, temperature differences this large can create potential comfort and moisture problems”. As well, it yields a more humid environment and increases the potential for mould growth.
As for energy savings, research from the Canadian Centre for Housing Technology states that: “winter setbacks for the houses tested would result in heating cost savings of five to fifteen per cent. The highest savings came with a setback of 6°C (11°F). Savings for the summer were about the same, although simply raising the thermostat set point in the summer from 22°C (71°F) to 24°C (75°F) led to more significant savings than the set-forward strategy and also offered better indoor humidity control. Note that these savings are for two airtight, well-insulated, unoccupied houses. The savings in your home may vary but are likely to be in the same range.”
If you’re not doing this already, consider giving it a try and monitor your results!