4 ms·

Before someone chimes in with the obvious suggestions: a) Water heater is a heat pump set to high efficiency. b) Construction is 2016, so relatively new. c)

by jhatax 4y ago

Before someone chimes in with the obvious suggestions: a) Water heater is a heat pump set to high efficiency. b) Construction is 2016, so relatively new. c) We have done a lot to insulate the home. Net-net, this is an electricity cost issue; we are paying $0.42/KWH on average. This despite having some solar. This is not a profligate usage issue.

deleted 4y ago
[deleted]
danans 4y ago
If you don't have gas service, how do you do space heating? Resistive electric? If so that could be very expensive. Also, insulation only deals with radiative heat losses and gains, not those causes by air leakage and conduction. High air leakage is quite possible for a 2016 house (especially in California where a lot of production built housing has been of poor quality). > Net-net, this is an electricity cost issue; we are paying $0.42/KWH on average The current time of use peak summer rate is $0.42/kWh. The winter off peak is $0.30/kWh. The only way you can be paying an average of $0.42 is if all your consumption for the year is between 4pm and 9pm during the summer, which is impossible.
- jhatax 4y ago
  We have two external units that serve to both heat and cool, one for each zone / floor. Bryant is the manufacturer, if memory serves. Summer on-peak is $0.49 per KWH (1). Our average is $0.38, I had a math error. Even with my error, the price of electricity in California is exorbitant and the grid is easily stretched to the limit => both will be exacerbated by increased demand from EVs and housing without gas lines. My math mistake doesn’t change the overall narrative. 1. 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...
  - danans 4y ago
    > We have two external units that serve to both heat and cool, one for each zone / floor. All else equal, a heat pump in the Bay Area should cost about the same or slightly less to operate as a natural gas furnace during the heating season. Natural gas is 3x cheaper than electricity per unit of energy, but heat pumps run at near-optimal efficiency in the local climate. Over the heating season mine achieves an average COP of 4.0 (4 units of heat for every 1 unit of electricity input). > Bryant is the manufacturer, if memory serves. It's a worthwhile exercise to look up the expected maximum efficiency of your unit to see if it is achieving that. > Even with my error, the price of electricity in California is exorbitant and the grid is easily stretched to the limit => both will be exacerbated by increased demand from EVs and housing without gas lines. Prices for electricity are absolutely high in California compared to other states. This is for many reasons, not the least of which is the cost of natural gas itself, which sets the spot price paid for all other sources. It's also because of the utility maintenance issues brought to light by the wildfires. However, according to PGE's own data, the average household gas bill this January is $195/month. That's on top of what people are paying for electricity. 2 years ago, it was $114/month [1]. That is a 72% increase. In the same time period, average annual natural gas only rates went up by 27%. The reason for the discrepancy is that natural gas pricing is moving toward more closely matching seasonal price variations, so much higher price/therm in the winter and lower in the summer. For 2023, winter rates will be 40% higher than summer rates, whereas in 2021 that difference was only 10%. Therefore today, you would probably be paying more to heat the same house with a natural gas furnace than with a heat pump. The vast majority of people who use natural gas for heating are discovering that reality right now. Furthermore, there's not much of a future in which natural gas gets cheaper as an energy source during the heating season. That's just the reality of that energy source. Meanwhile, peak electricity rates have increased 22% since 2021 (when peak rates were $0.40/kWh), but the seasonal variations in electricity demand are currently the opposite of natural gas (lowest in winter, highest in summer). In the long term, we can expect winter electricity demand to rise as more heat pumps are deployed. However, even if we exclusively burned natural gas (which we won't) to generate the electricity to meet that demand, it makes far more sense to do so in a combined cycle plant that is 50-60% efficient and sending it to heat pumps getting 3-4 COP, yielding a 200%+ "efficiency", than to burn it in furnaces that achieve on average 80% efficiency. 1. https://www.pge.com/tariffs/Residential.pdf https://www.pge.com/tariffs/Residential.pdf
tuatoru 4y ago
Re c), you may have done a lot, but clearly not enough. Good insulation needs balance. Try a FLIR survey and a positive pressure test survey of the house. Those should help direct future insulation efforts.
icedistilled 4y ago
Missing some important data pieces: is it a giant house or small house? Is it heating/cooling the entire house including the spare bedroom(s) or zone ac/heating.

by jhatax 4y ago

deleted 4y ago

[deleted]

danans 4y ago

If you don't have gas service, how do you do space heating? Resistive electric? If so that could be very expensive. Also, insulation only deals with radiative heat losses and gains, not those causes by air leakage and conduction. High air leakage is quite possible for a 2016 house (especially in California where a lot of production built housing has been of poor quality). > Net-net, this is an electricity cost issue; we are paying $0.42/KWH on average The current time of use peak summer rate is $0.42/kWh. The winter off peak is $0.30/kWh. The only way you can be paying an average of $0.42 is if all your consumption for the year is between 4pm and 9pm during the summer, which is impossible.

jhatax 4y ago
We have two external units that serve to both heat and cool, one for each zone / floor. Bryant is the manufacturer, if memory serves. Summer on-peak is $0.49 per KWH (1). Our average is $0.38, I had a math error. Even with my error, the price of electricity in California is exorbitant and the grid is easily stretched to the limit => both will be exacerbated by increased demand from EVs and housing without gas lines. My math mistake doesn’t change the overall narrative. 1. 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...
- danans 4y ago
  > We have two external units that serve to both heat and cool, one for each zone / floor. All else equal, a heat pump in the Bay Area should cost about the same or slightly less to operate as a natural gas furnace during the heating season. Natural gas is 3x cheaper than electricity per unit of energy, but heat pumps run at near-optimal efficiency in the local climate. Over the heating season mine achieves an average COP of 4.0 (4 units of heat for every 1 unit of electricity input). > Bryant is the manufacturer, if memory serves. It's a worthwhile exercise to look up the expected maximum efficiency of your unit to see if it is achieving that. > Even with my error, the price of electricity in California is exorbitant and the grid is easily stretched to the limit => both will be exacerbated by increased demand from EVs and housing without gas lines. Prices for electricity are absolutely high in California compared to other states. This is for many reasons, not the least of which is the cost of natural gas itself, which sets the spot price paid for all other sources. It's also because of the utility maintenance issues brought to light by the wildfires. However, according to PGE's own data, the average household gas bill this January is $195/month. That's on top of what people are paying for electricity. 2 years ago, it was $114/month [1]. That is a 72% increase. In the same time period, average annual natural gas only rates went up by 27%. The reason for the discrepancy is that natural gas pricing is moving toward more closely matching seasonal price variations, so much higher price/therm in the winter and lower in the summer. For 2023, winter rates will be 40% higher than summer rates, whereas in 2021 that difference was only 10%. Therefore today, you would probably be paying more to heat the same house with a natural gas furnace than with a heat pump. The vast majority of people who use natural gas for heating are discovering that reality right now. Furthermore, there's not much of a future in which natural gas gets cheaper as an energy source during the heating season. That's just the reality of that energy source. Meanwhile, peak electricity rates have increased 22% since 2021 (when peak rates were $0.40/kWh), but the seasonal variations in electricity demand are currently the opposite of natural gas (lowest in winter, highest in summer). In the long term, we can expect winter electricity demand to rise as more heat pumps are deployed. However, even if we exclusively burned natural gas (which we won't) to generate the electricity to meet that demand, it makes far more sense to do so in a combined cycle plant that is 50-60% efficient and sending it to heat pumps getting 3-4 COP, yielding a 200%+ "efficiency", than to burn it in furnaces that achieve on average 80% efficiency. 1. https://www.pge.com/tariffs/Residential.pdf https://www.pge.com/tariffs/Residential.pdf

tuatoru 4y ago

Re c), you may have done a lot, but clearly not enough. Good insulation needs balance. Try a FLIR survey and a positive pressure test survey of the house. Those should help direct future insulation efforts.

icedistilled 4y ago

Missing some important data pieces: is it a giant house or small house? Is it heating/cooling the entire house including the spare bedroom(s) or zone ac/heating.