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.
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?
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+%.
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.
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.
(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.
Why are you measuring natural gas in kWh? How do you even measure that as such?
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.
This is fascinating to me. 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.
To turn gas to electricity assume 50% efficiency. 2MWh of gas = 1MWh of electricity.
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?
It would equal about 22kWh of gas, since gas isn’t 100% efficient like electric heat is.
Ah. 50% efficency to turn gas into electricity.
If you are just making heat then burning gas directly is much better.
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+%.
It does not factor efficiency at all.
The bill does not care about efficiency.
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
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.
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.
Yeah, even firewood can be (and not uncommonly is) measured in kWh
(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.
My meter measures it in m3 and my supplier, knowing the exact caloric value of the product they’re selling, tells me in kWh on my bill.
edit: m3 of course not 2 lol