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The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat. On the very

The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat. On the very coldest days the efficiency of a heat pump can drop enough for this not to be the case, but over the course of the year an electric heat pump will save you money over burning gas. There are pretty significant environmental costs to burning gas in our homes, less about the combustion exhaust than the total amount of leaks within the distribution system that allow unburned methane to escape to the atmosphere. There's also growing awareness that many classes of gas appliance produce a lot more indoor air pollution that causes lung disease (especially in children) than was previously expected.

rahimnathwani 4y ago
"The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat." This must depend on the relative prices of gas and electricity. What's the threshold ratio beyond which gas is cheaper than a heat pump?
- hedora 4y ago
  It generally takes less gas to generate electricity, ship it, and run the heatpump than to directly heat the house with gas.
  - rahimnathwani 4y ago
    But I don't generate or ship electricity. I buy both my electricity and my gas from PG&E, and pay whatever price they charge for each. So the question of which is cheaper depends not on the fundamentals of physics of it, but on the relative prices PG&E charges for each.
    - hedora 4y ago
      In California, the heat pump will win, partially due to the mild climate, and partially due to natural gas somehow being even more overpriced than electricity.
      - rahimnathwani 4y ago
        I pay PG&E: * ~$0.35/kWh for electricity * ~$2/therm for gas (equivalent to ~$0.07/kWh according to a quick search). Even though I pay 5x the price for electricity as I do for gas, a heat pump will be cheaper?
        hedora 4y ago
        You get a lower rate (higher baseline) if you install a heat pump ($0.28-0.30; 4x to 4.2x), and the coefficient of power for the heat pump should be well over 4 in California. Current electricity rates: https://www.pge.com/pge_global/common/pdfs/rate-plans/how-rates-work/Residential-Rates-Plan-Pricing.pdf https://www.pge.com/pge_global/common/pdfs/rate-plans/how-ra... Current natural gas rates: https://www.pge.com/tariffs/GRF1122.pdf https://www.pge.com/tariffs/GRF1122.pdf You seem to be on the cheaper residential schedule.
        rahimnathwani 4y ago
        > You seem to be on the cheaper residential schedule. I'm in San Francisco, so PG&E bills me separately for distribution (provided by PG&E) and generation (provided by CleanPowerSF). We are on a rate plan that has slightly cheaper electricity off peak, and save something like $20/year as a result. The individual line items on the bill are hard to understand (lots of surcharges and credits), but I can tell you from the totals that my most recent bill shows $0.33 per kWh for electricity (average, including both delivery and generation) and $2.56 per therm for gas.
aaron695 4y ago
> The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat I'd call bullshit on this. But looking at the figures in Washington you'd need a air sourced heat pump to average 260%, which is said to be possible. It wouldn't be worth upgrading, but subsidised installation on new homes could/should work. > pretty significant environmental costs to burning gas No > gas appliance produce a lot more indoor air pollution Yes
idiotsecant 4y ago
>The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat. On the very coldest days the efficiency of a heat pump can drop enough for this not to be the case, but over the course of the year an electric heat pump will save you money over burning gas. I am not arguing any point you're making other than this. This statement is heavily dependent on how cold your winter is and the relative costs of electricity and natural gas. Some years it might pencil out, but some years it won't . I'm not sure without looking at historical data I could say the ratio between the two with certainty, especially given the typically very cheap natural gas over the last decade (although recently of course this calculus changes!) I'm just arguing for some nuance - the linked article is breathlessly claiming things that I think we should charitably say are bending the truth a bit. If I had to install a heat pump tomorrow I would do it and it wouldn't impact me, even if it cost a few buck throughout the year. I think most people on HN are probably in that same class. There are a large swatch of people, on the other hand, for whom a few dollars is very meaningful and a temporary tax credit is great and all but when they expire if we are asking those people to shoulder the cost of this decision we should do so carefully.

rahimnathwani 4y ago

"The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat." This must depend on the relative prices of gas and electricity. What's the threshold ratio beyond which gas is cheaper than a heat pump?

hedora 4y ago
It generally takes less gas to generate electricity, ship it, and run the heatpump than to directly heat the house with gas.
- rahimnathwani 4y ago
  But I don't generate or ship electricity. I buy both my electricity and my gas from PG&E, and pay whatever price they charge for each. So the question of which is cheaper depends not on the fundamentals of physics of it, but on the relative prices PG&E charges for each.
  - hedora 4y ago
    In California, the heat pump will win, partially due to the mild climate, and partially due to natural gas somehow being even more overpriced than electricity.
    - rahimnathwani 4y ago
      I pay PG&E: * ~$0.35/kWh for electricity * ~$2/therm for gas (equivalent to ~$0.07/kWh according to a quick search). Even though I pay 5x the price for electricity as I do for gas, a heat pump will be cheaper?
      - hedora 4y ago
        You get a lower rate (higher baseline) if you install a heat pump ($0.28-0.30; 4x to 4.2x), and the coefficient of power for the heat pump should be well over 4 in California. Current electricity rates: https://www.pge.com/pge_global/common/pdfs/rate-plans/how-rates-work/Residential-Rates-Plan-Pricing.pdf https://www.pge.com/pge_global/common/pdfs/rate-plans/how-ra... Current natural gas rates: https://www.pge.com/tariffs/GRF1122.pdf https://www.pge.com/tariffs/GRF1122.pdf You seem to be on the cheaper residential schedule.
        rahimnathwani 4y ago
        > You seem to be on the cheaper residential schedule. I'm in San Francisco, so PG&E bills me separately for distribution (provided by PG&E) and generation (provided by CleanPowerSF). We are on a rate plan that has slightly cheaper electricity off peak, and save something like $20/year as a result. The individual line items on the bill are hard to understand (lots of surcharges and credits), but I can tell you from the totals that my most recent bill shows $0.33 per kWh for electricity (average, including both delivery and generation) and $2.56 per therm for gas.

aaron695 4y ago

> The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat I'd call bullshit on this. But looking at the figures in Washington you'd need a air sourced heat pump to average 260%, which is said to be possible. It wouldn't be worth upgrading, but subsidised installation on new homes could/should work. > pretty significant environmental costs to burning gas No > gas appliance produce a lot more indoor air pollution Yes

idiotsecant 4y ago

>The electricity to run a heat pump that moves heat where you want it is cheaper than the gas you need to burn to make an equivalent amount of heat. On the very coldest days the efficiency of a heat pump can drop enough for this not to be the case, but over the course of the year an electric heat pump will save you money over burning gas. I am not arguing any point you're making other than this. This statement is heavily dependent on how cold your winter is and the relative costs of electricity and natural gas. Some years it might pencil out, but some years it won't . I'm not sure without looking at historical data I could say the ratio between the two with certainty, especially given the typically very cheap natural gas over the last decade (although recently of course this calculus changes!) I'm just arguing for some nuance - the linked article is breathlessly claiming things that I think we should charitably say are bending the truth a bit. If I had to install a heat pump tomorrow I would do it and it wouldn't impact me, even if it cost a few buck throughout the year. I think most people on HN are probably in that same class. There are a large swatch of people, on the other hand, for whom a few dollars is very meaningful and a temporary tax credit is great and all but when they expire if we are asking those people to shoulder the cost of this decision we should do so carefully.