• CoriolisSTORM88@lemmy.world
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    8 months ago

    So this interests me. I live in a home built in 1920. I have a modern ish furnace installed in 2012. I used 143CCFC of natural gas in January due to the severe cold, for a bill of $226.56. I used Copilot to tell me how to calculate this, so if it is wrong, please let me know. 1 CCFC is 2.832 cubic meters. So I used 404.976 cubic meters of gas. 1 cubic meter of gas is 11 kWh roughly. So I used 4454.726 kWh worth of gas last month. My electric rate from the bastards at Alabama Power/Southern Company is $0.114207 per kWh. So to use electricity, my bill would be $508.76 instead. A swag at furnace efficiency means roughly 80% of my gas went to heating my house. So even reducing that kWh by 20% doesn’t put me ahead. 3565.368 kWh at $0.114207 is still $407.19. Am I missing something? Did Copilot mislead me? Because the savings aren’t there from this math. How do I factor heat pump efficiency in here?

    • silence7@slrpnk.netOPM
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      8 months ago

      What you’re missing is that heat pumps move heat, instead of just turning electricity into heat. How efficient they are at this varies by heat pump, and by outside temperature. During extreme cold, you might really spend more, but the rest of the year, you end up moving 3-5 kwh of heat for each kwh you consume, so your overall bill over the course of a year ends up being lower.

    • user134450@feddit.de
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      8 months ago

      first you would need to know what COP you could reasonably get, which among other things depends on the average outside temperature during heating season if you want to use an air sourced heat pump.

      The COP can be in a largish spectrum depending on these factors but typical values are 3.5 for average homes in temperate climate. Higher if you live in a warmer climate and lower if you live closer to the arctic. If you want to really do the math it might be good to get help from a professional specialising in heat pumps.

      Edit: this is for heating use only. A heat pump can also be used for cooling but then the climate effect is inverted.