That massive spike of 50c/kWh at the left looks tiny compared to today even though that's already insanely expensive

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[–] 20 points 2 years ago (31 children)

How are you using 21kWh/day heating a small home? Do you have any insulation at all?

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  • [–] 27 points 2 years ago (2 children)

    That's a perfectly normal number for any home that isn't very new and perfectly insulated.

    My 37sqm appartment needs approximately 5000 kWh in natural gas per year, 876 kWh last December, so 28 kWh per day on average. The building is admittedly old and not perfectly insulated but it's also not a log cabin out in the open in Finland, but instead a flat enclosed within 3 other flats in the middle of cosy, never below -8C Germany.

    21 kWh in a log cabin in Finnland actually seemed pretty low to me. It's sort of obvious OP is using a heat pump and the cabin must really be absolutely tiny.

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  • [–] 2 points 2 years ago (3 children)

    Why are you measuring natural gas in kWh? How do you even measure that as such?

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  • [–] 18 points 2 years ago* (last edited 2 years ago) (1 child)

    It's an easy conversion - 1 kWh is equal to 3412 Btus. In Germany, both electricity and natural gas are charged in kWh. I know a fair bit about energy measurement if you have any questions.

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  • [–] 6 points 2 years ago (4 children)

    This is fascinating to me. How does it factor efficiency, since gas needs to be burned?

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  • [–] 4 points 2 years ago* (last edited 2 years ago)

    Great question. When it comes to utility billing, efficiency doesn't factor at all. Just like with electric billing, the utility company gives zero shits about what you do with your energy. They just bill you for everything you use.

    Utility companies keep track of the volume used in cubic meters and convert it to kWh using the formula...

    Volume (in cubic meters) • Calorific value (usually around 37-42) • 1.02264 (correction factor) ÷ 3.6 (conversion factor to kWh) = kWh

    The calorific value accounts for the varying energy density of natural gas caused by its inconsistent composition. The correction factor accounts for the effects of the average temperature and pressure at the property on gas volume measurement. 1.02264 is standard for most locations but would be different if the location is extreme, like the high elevation of Machu Picchu.

    What sucks about gas heating is some of the heat energy released leaves with the exhaust. The heating efficiency varies depending on the unit but is generally 90-95% for newer units but as low as 50% for older units. While 90-95% doesn't seem bad, electric heat pumps achieve efficiencies that exceed 100%, even as high as 300+%.

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  • [–] 4 points 2 years ago (1 child)

    To turn gas to electricity assume 50% efficiency. 2MWh of gas = 1MWh of electricity.

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  • [–] 4 points 2 years ago (2 children)

    So given that most gas furnaces (at least in the US) operate at 90-95% efficiency, does that mean 20 kWh of resistive electric heat (as measured on the bill) provides similar heat to ~11 kWh of gas?

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  • [–] 4 points 2 years ago

    How does it factor efficiency, since gas needs to be burned?

    Energy is energy regardless of what unit is used to show it. so 3412 BTUs always equals 1kWh.

    You do an efficiency calculation after, average gas blower is about 90% so you'd end up with 3070 BTUs or 0.9kWh of heat energy.

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  • [–] 14 points 2 years ago (1 child)

    Very common in countries that use the metric system (ie literally everywhere except the USA). It's measured either in kWh or in m^3

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  • [–] 2 points 2 years ago* (1 child)

    Cubic meters (or another similar measure of volume) is what I'd expect. It's the conversion to an unrelated and theoretical (since it's not actually being converted to electricity) unit that confuses me. I presume it's to make it easier to compare electric vs gas heat, but the variable efficiency of burning gas and the existence of heat pumps ruin that.

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  • [–] 11 points 2 years ago (2 children)

    kWh is a unit of energy. Regardless of whether it is in the form of electricity or from burning fuel. So it is actually very related, and much more useful than a measurement of volume I'd argue. The measurement is of course done in m³, but then a conversion factor based on several factors is used to convert to an actually useful unit.

    A m³ of gas really could be anything depending on pressure, temperature and constituents.

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  • [–] 2 points 2 years ago

    (Brace yourself for Much 'Merica) Several gas utilities I've had in the USA measure natural gas CCF, which is 100 cubic feet (at some standard temperature/pressure), which happens to be almost exactly the same as a Therm, or 100,000 BTU.

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  • [–] 4 points 2 years ago* (last edited 2 years ago)

    My meter measures it in m^3^ and my supplier, knowing the exact caloric value of the product they're selling, tells me in kWh on my bill.

    edit: m^3^ of course not ^2^ lol

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  • [–] [S] 25 points 2 years ago* (last edited 2 years ago)

    50kWh and closer to 90kWh on days like this. It's a log cabin and I'm keeping my root cellar and insulated shed above freezing aswell. Even running a 1kW heater all day would result in a consumption more than 21kWh and that wouldn't keep any house warm.

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  • [–] 18 points 2 years ago

    A tiny heater running all day would do that.

    1kw is a small heater. 0.8kw is a tiny one. 0.8x24 is 19.2. Assuming they have other basic appliances, that's already more than enough to account for their usage.

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  • [–] 10 points 2 years ago (1 child)

    I’ve got a small 1200w heater that kicks on in the morning to bring the living room space up to 69. I live in a 40 year old house that’s insulated fairly well (I just had the attic redone last year to r-49) and it’s 45f outside right now. That little heater has used 6kWh since kicking on this morning getting the house up from 63f to the near 69 it is now.

    On a day below freezing that heater will got for a lot longer through the day to keep temps up.

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  • [–] 6 points 2 years ago* (10 children)

    Space heaters are the way to go.

    It's the difference between paying $70 and $5 more per month.

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