Home heating efficiency
by Carol
(Ireland)
Which provides the best home heating efficiency and lowest energy cost when using oil and a condenser boiler:
- Having the thermostat up higher for a shorter period during the evenings, OR
- Having the thermostat lower and heating on for a longer period?
Answer from Green Energy Efficient Homes
Home heating efficiency for a condenser boiler or other fossil fuel source is best achieved by never heating your home warmer than it needs to be at that time. The bigger the difference in temperature between the indoors and outdoors, the more heat will escape through your walls, windows, and any openings (cracks/drafts) to the out-of-doors. So setting the thermostat really high and letting the temperature rise to tropical temperatures in the evening, then letting it coast down at night, will mean more heat is escaping your home at the times your home is warmer.
It's always better to keep your home at the lowest required temperature at any given time. For example many people use a programmable or setback thermostat, where you can set the temperature to rise to comfort level (e.g. 68F / 20C) just before you get up, back down to economy level (e.g. 62F / 17C) just before you leave for work/school, back up to comfort level around the time you get home from work or school, and back down to economy level around bedtime.
The only exception to this is for homes that are heated with electricity, where the homeowner pays different rates at different times of the day. In this case, it might be better to warm your house up higher than comfort level when electricity is cheap, so that you're using less electricity during peak rate times. However, the effectiveness of this approach will depend on how good your insulation is. In a very well insulated house, most of that heat will stay in the house long enough that you'll save money on heating. In a very poorly insulated or drafty house much of the heat obtained during low electricity rate periods may escape to the outside before the higher peak rate kicks in.
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