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Weaning households off natural gas, heating oil, and other fossil fuels would mean significant reductions in carbon emissions, but there’s a catch. From furnaces to water heaters to kitchen ranges, fuel-burning appliances are deeply entrenched in U.S. homes. Even homeowners who’d like to go all-electric may feel overwhelmed by the complexity and expense of the conversion.
For people who find themselves in this boat, a California energy consulting firm has some reassuring news: The process can be simple, relatively inexpensive, and require no building modifications, not even an upgrade in the electrical service panel to anything over 100 amps.
“You are not alone in this project of electrifying your home,” says the introduction to A Pocket Guide to All-Electric Retrofits of Single-Family Homes. “And it can be cheap and easy.”
The guide was produced by Redwood Energy, zero-net energy specialists in multifamily housing, for a non-profit community organization called Menlo Spark. It’s one of several publications Redwood has produced that are aimed at accelerating a trend toward the use of electric devices. “The global scientific community says that fossil fuels burned in our buildings are causing 28% of climate change,” it adds, “with natural gas leaks upstream of our appliances responsible for another 25% of global climate change.”
In a telephone call, Redwood’s Managing Principal Sean Armstrong said the new pocket guide is the latest in a series on electrification that also covers commercial buildings, new single-family homes, and multifamily projects. After publishing the single-family guide at the beginning of 2020, the company turned its attention to the retrofit publication and has been working on it for the last year. An early draft went out for peer review and the company posted a final version at its website within the last couple of weeks.
The earlier booklet on commercial construction was intended to help big companies electrify new construction. That turned out to be “modestly successful,” Armstrong said, with Adobe and LinkedIn committing to a couple of all-electric construction projects.
“The booklet did something,” he said. “It changed people’s thinking. It got in front of people and helped them see what options were there.”
The benefits of going all-electric
Cutting carbon emissions from buildings is an important part of government efforts to slow global climate change. Some green builders also are getting pickier about the building materials they use in an effort to cut the embodied carbon in new construction.
Redwood Energy cites a variety of other benefits to electrification:
- Better indoor air quality and better health. Children in homes with gas stoves are 42% more likely to develop asthma, and home chefs using gas stoves have twice the risk of developing lung cancer and heart disease.
- Enhanced safety. Electric cooktops, water heaters, and other appliances are less likely to cause fires and explosions than devices powered by gas.
- Lower costs. Households with all-electric appliances can save as much as $800 a year on utility bills. The installation of solar arrays can mean even greater savings.
- Greater comfort. Heat pumps are quieter and produce heat more consistently than gas-fired furnaces that cycle on and off; electric stoves produce half as much waste heat as gas-fired ranges.
Potential savings from going all-electric were outlined in another report, this one from the Rocky Mountain Institute (RMI) that was released late last year. It predicted savings in an all-electric new house in seven U.S. cities compared with a mixed-fuel home that used gas for cooking, space heating, and water heating. Savings ranged from $1600 in net present costs and reduced carbon emissions of 51 tons over 15 years in Boston, to a high of $6800 in savings and 46 fewer tons of C02 in New York City. Other cities covered in the RMI survey included Austin, Columbus, Denver, Minneapolis, and Seattle.
RMI has published a number of articles on electrification, including this one late last year summing up progress toward that goal in a number of states.
Despite the new attention it’s getting, electrification really isn’t new, Armstrong said. It can be traced to the Rural Electrification Administration created in 1935 by President Franklin Roosevelt; later, it found a big advocate in President Ronald Reagan.
“It’s been a 70-year-long movement,” Armstrong said, and should not be viewed as a partisan issue.
Two paths to all-electric
The Redwood Energy guide sees two paths toward electrification: an appliance-by-appliance conversion, which it calls “box swapping,” and deep retrofits that may include improvements to the building enclosure. “Either of these types of retrofits can be done quickly, or phased in over the course of years,” the authors say, “depending on the owner’s needs.”
Costs will vary widely. In an incremental conversion, where a gas-burning appliance is replaced with an electric model, there may be no cost difference between the two options other than running electricity to the new appliance. When all appliances are replaced at once, costs may range from $3000 on the low end—an option that includes a two-burner countertop induction range rather than a full-size stove, for example—to $20,000 or more. “Every house is different,” the authors note, “and people have different tastes and desires.”
In case studies from Energy Smart Ohio, total retrofit costs were as high as $49,700 in a 2700-square-foot home built in 1966, a project that included roughly $20,000 in upgrades to the building enclosure. At the low end was $10,675 for a 1617-square-foot house where space and water heating equipment was replaced but no improvements were made to the building enclosure.
The authors of the report looked at the box-swapping option a room at a time, presenting the cost of converting from a gas appliance to one of several types of electrically powered appliance. In this case, it may be possible to avoid retrofit costs by choosing an appliance of the same size, and avoid wiring upgrade costs by using energy efficient equipment or by using devices called power-sharing plugs.
The cost of a conversion, of course, depends on the appliance. To replace a gas range with an electric model, a consumer could spend less than $1000 for a 24-inch model to an average of more than $1500 for a 36-inch-wide model (not including the cost of running a new electrical circuit). Converting to a heat-pump water heater is more expensive (costs averaged around $4000 in Sacramento, California, for a 50-gallon model, including labor and materials) but the big nut to crack is probably space heating. Redwood Energy said that it developed its estimates after contractors from different parts of the country agreed to share their bids. A house typically required between 1 and 3 tons of capacity (12,000 to 36,000 Btu/hour) for heat, with per-ton costs ranging from a low of about $3100 to a high of $6000 in the states that were sampled.
Variables would, of course, include insulation, windows, measured heat loads, and the condition of any ductwork that was used in a retrofit. End costs to consumers also would hinge on what rebates a particular state offered for a targeted appliance. One place to check for those is at the Database of State Incentives for Renewables & Efficiency, which is maintained by the North Carolina Clean Energy Technology Center.
Avoiding expensive electrical upgrades
Many new homes get 200-amp service panels, providing plenty of electricity for appliances (with the exception of outliers like electric tankless water heaters). But older houses are often stuck with 100-amp panels, sometimes less, and wiring that has been modified by well-meaning amateurs to the point where some circuits are overloaded, some are under-used, and the system is generally something of a mystery.
Homeowners thinking about upgrades to appliances that draw a lot of power might have second thoughts if the work would necessarily include major rewiring and an upgrade to a 200-amp service entrance. Running 240-volt cables to stoves, water heaters, clothes dryers, and space heating equipment costs as much as $600 per circuit and averages $300, the guide notes, while a new service panel averages $1475.
That said, there are ways of using the power that’s available without a panel upgrade while still following the National Electrical Code (NEC), as the authors say: “We call this process of avoiding power upgrades a ‘Watt Diet,’ which involves power-efficient appliances and sometimes power balancing plugs.”
In fact, the report says a 100-amp panel has enough electricity to completely electrify a 3000-sq.-ft. home. Most houses need no more than the NEC minimum of a three-wire, 100-amp service entrance. To bolster its case, the guide describes a set of appliances that would fit into an all-electric, 100-amp home, including a 21-amp heat-pump water heater and a 3-ton heat pump for heating and cooling.
Armstrong said that in figuring out how to make seemingly under-sized service panels take care of an all-electric house, it’s important to understand the difference between actual electrical draw and the capacity of the circuit breaker. For example, a water heater may require a 30-amp, 240-volt breaker, but that doesn’t mean it’s actually using that much electricity.
“The breaker is not the issue,” he said, “it’s really the electrical demand.”
The report’s recommendations to make all of this possible include:
- Use heat pumps rather than electric resistance heating. Heat pumps are between 3 and 5 times as efficient.
- Get a condensing, combined washer/dryer, which can be plugged into any 120-volt outlet and does not have to be vented to the outside.
- Use a combined range and oven rather than separate units, and put the microwave oven on the counter rather than attaching it to the wall where it would require a dedicated circuit.
- Insulate and air-seal the house to reduce heating loads.
- Use circuit-sharing plugs, which allow one 240-volt outlet to power both an electric vehicle and an electric appliance. Once such device is the NeoCharge.
The same could be accomplished with a 3000-square-foot house, the report adds, when automatic circuit sharing devices are added for an electric dryer and heat-pump water heater, and for an electric stove and electric vehicle.
Elsewhere at the Redwood Energy site is a downloadable app called the Watt Diet Calculator that can be used to estimate how much electricity will be used and whether the electrical panel will have to be upgraded.
Devices that don’t need 240-volt circuits
Switching to electrically powered water heating or space heating and cooling usually means running new 240-volt lines, but that’s not always necessary. While the pocket guide lists a number of heat-pump water heaters that require 240-volt circuits, it also includes two that run on 120-volt current, meaning they could be plugged into any households circuit.
The pocket guide lists two—the GE GeoSpring, available in 40- and 50-gal. sizes, and the Rheem Prestige Hybrid, a 40-gal. model. Armstrong said in a telephone interview that A.O. Smith also would begin offering a similar model this year.
(Rheem, however, said in an email that it does not currently offer a 120v model and declined to say if or when it would in the future. GE no longer produces GeoSpring heat-pump water heaters. Bradford White, which took over the GeoSpring line in 2017 and now sells them under the AeroTherm label, said there is no pending release of a 120v model. A.O Smith didn’t respond to requests for information.)
Four manufacturers offer portable heat pumps running on 120-volt circuits that can plug into any outlet in the house. Ducts fit into a window opening. They include models from Edge Star, Black + Decker, Whynter, and Haier. The Black+Decker draws a maximum of 9 amps and has a heating capacity of as much as 11,000 Btu/hour.
Don’t feel like investing $1000-plus in a new induction range? What about a single-burner induction burner you can plug into a 120-volt circuit? The guide lists more than a dozen models, both countertop and drop-in, available for as little as $40. Two-burner, 120-volt models are available for $150.
These products are part of an extensive catalog of devices that cover everything from heating and cooling to cooking, water heating, whole-house ventilation, countertop ovens, kitchen hoods, and even slow cookers. There’s even a section on electrically powered landscaping tools like chainsaws, lawnmowers, and hedge trimmers, plus a listing of three battery-driven snowmobiles.
Scott Gibson is a contributing writer at Green Building Advisor and Fine Homebuilding magazine. This post was updated on March 25 to include new information about heat-pump water heaters.
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61 Comments
Wow, that's a great guide! Including introducing some products that I didn't know existed, such as 120 V heat-pump water heaters for retrofits where a new 240 V circuit isn't feasible.
One important aspect that they under-emphasized is sizing the new heating system. Replacing the gas furnace, which is likely 2X oversized, with a new 2X oversized heat pump isn't going to work out well. For both this reason and for planning for electric service capacity, I recommend that everyone who is interested in electrification start by installing an electric monitoring system such as IotaWatt, including submetering on the HVAC equipment, right away, while you consider your other options. And if envelope upgrades are in the cards, do them soon so you can have some monitoring data after the upgrades are completed.
I couldn't find a 120 volt Rheem HPWH on the company's website. I only see the 15 amp/220 volt version, which was introduced a few years ago. It also appears the Geospring is no longer in production.
Steve,
Thanks for that alert. I'll check on the availability of those models.
Scott
Bradford White took over GE's water heating manufacture, including GeoSpring.
Announced and syndicated a few years ago, but here's one archive: https://www.achrnews.com/articles/134479-bradford-white-acquires-production-assets-from-ge-appliances
I have the Bradford Aerotherm 50gal HPHW. Supposedly the Aerotherm models are / have some of GE's Geospring technology.
Great article, Scott! One thing I learned last month after the TX freeze, when DOE made TX a CZ9 for 2 weeks, is that net metering may not work if the grid is shut down. We learned that solar panels installed in low pitch roofs don't shed the snow off so they don't produce electricity (what ya know!). We learned that a fully charged set of batteries last a couple or three days, without recharging (see panels covered in snow above).
Since we saw that a tightly sealed and insulated envelope works well in an emergency, in some of these large homes(without calling the size police), we need to rethink about having a gas generator and maybe a way to close a portion of a house that can be used as "emergency shelter", maybe around the kitchen, a bath and a small portable heater or DV fireplace.
Anyways, there is plenty of room for improvement on the resilient design department. Any more ideas?
The shelter likely could be a regional distinction. In tornado areas, a storm shelter underground with power, ventilation, and water might be preferable. I don’t know about hurricane areas (have never lived there) but I assume those folks would want to evacuate. That said, a “pretty good house” is going to be warmer for a longer time in winter than an unheated storm cellar or root cellar in a terrible winter storm.
I've almost converted everything to electric (only gas appliance left is water heater) but my winter costs have gone up considerably now that I'm heating with a mini-split. I've got an older house in the SF-Bay area so in-wall insulation in half of it is poor/non-existant and I've still got some drafts. Granted if/once I get solar I'll barely need the grid but I'm looking at at least another $10K to DIY solar with battery backup.
All that to say that in mild climates it feels like it's hard to see any cost savings unless you also have the capital outlay to add solar. Thankfully my main motivation was to get gas and gas burning appliances out of the house (can't wait to turn off the gas meter!) and not cost savings.
The ratio of gas price versus electric price in different parts of the country varies greatly. And the climate also affects how much electricity heat pumps use to put out a given amount of heat. Right now in a lot of places the motivation has to be to reduce your climate impact. With a price on carbon, we would make that decision a lot easier for a lot of people to make.
What is "a price on carbon"?
IMHO this is where the rubber meats the road. Consumers do not directly pay money for carbon. (There are a few who pay for RECs but they're still paying for electrons.) Consumers do pull money out of their wallets for electrons / gas / etc utilities. It's a long, hard march to convince people how they indirectly "pay" when the money being debated doesn't come directly from their wallets. So I don't think the decision is made easier.
I agree with Alex. My electricity bills have gone UP after going all electric -- I am paying _more_ money out of pocket.
Did I switch from propane heat to energy efficient mini-splits? Yes.
Did I switch from "glow red" electric hot water to heat pump HW? Yes.
Did we replace all appliances & fixtures with EnergyStar? Yes.
Did we re-insulate the house with foam? Yes.
Did we get a blower door test done & re-seal cracks? Yes.
Electric bill is still higher. We need to be transparent about that reality.
One way to reduce that reoccuring expense of the high monthly electric bill is ... more money! A large outlay of capitol investement is needed by the consumer, i.e. installing solar panels, wind turbine. Solar panels that power this article's entire house load -- especially the EV car -- are not cheap. I know because I paid the money to get solar panels installed to get ride of my high electric bills -- but not every consumer has that kind of capitol! And even for those with the capitol, it's not been determined whether residential solar panels have an ROI for homeowners who sale a house with panels later on, so the financially wise won't go for the risk.
We need to be honest about the money involved here. Trying to explain away a high electric bill with carbon or "fixing" it with capitol investements in solar panels / wind that hits the consumer's wallet even harder will appear like we're playing smoke-and-mirrors about why the bill is bigger.
When I say a price on carbon, I mean public policy that would make the consumer price of natural gas go up, and perhaps make the consumer price of low carbon electricity go down. There are many challenges around how to do that in an effective, equitable, and politically viable way, but I didn't think this was the place to get into those discussions.
Ah, gotcha.
I agree with Alex. My electricity bills have gone UP after going all electric -- I am paying _more_ money out of pocket.
Did I switch from propane heat to energy efficient mini-splits? Yes.
Did I switch from "glow red" electric hot water to heat pump HW? Yes.
Did we replace all appliances & fixtures with EnergyStar? Yes.
Did we re-insulate the house with foam? Yes.
Did we get a blower door test done & re-seal cracks? Yes.
Electric bill is still higher. We need to be transparent about that reality.
I'm genuinely interested ... how do you explain your higher electricity bills? What difference are we talking 5% or less or are we talking 20% or more?
Have you changed habits because of the change to electric appliances? For example, do you run your heat at a higher temperature, more consistently/more often?
Just going from a standard electric water heater to a heat pump water heater has got to save $100's of dollars per year alone. As someone also in California (and on PG&E) who uses non-electric heat sources, I'm interested in what changes I can expect if changing to an electric heat source (mini-splits/heat pump).
I've been tracking my heating costs this winter past and I've been kind of surprised how expensive it has been (propane stove and a pellet stove), I'd hate to think going to an efficient electric mode of haeting would be much more.
Re heating costs:
To steal a GBA blog title, "it's not that hard". The key is to normalize the monetary cost of your energy source by its energy storage...BTUs or kWh. In my area, electricity costs 4.4 times more than natural gas. Then consider the effciency of energy transfer to heat output. For me, I need a COP of 4 from a heat pump to compete financially with a 90% efficient gas furnace. For a more realistic COP of 3, my cost for heating is 1.5x the cost of natural gas. I hope this helps.
Just as general info, my current winter rate using PG&E is 0.25/kwh. Googling electric rates in Wisconsin shows around 0.11/kwh. It's hard to account for specifics for individual accounts in both states.
Derek, I can buy a 40 lb bag of hardwood pellets at my local Lowes for $5.48. According to Wikipedia, the energy available in pellets is about 7,450 BTU's per lb. This comes to $0.062 per kWh. I get e!ectricity at $0.11 per kWh. Electricity is 1.75x more expensive. However, just about any heat pump will have a COP in excess of 1.75. Also, combustion efficiency of a pellet stove is maybe 85%.
Conclussion: Pellet stove is cheaper than resistance heat, but more expensive than any decent minisplit. And it modulates for greater comfort and efficiency.
Why would a consumer change their use _after_ making impovements??
I hear you say that you're "genuinely interested" but it sounds like the burden of proof is put on me (or consumers in general) who are supportive of the idea and are only being constructively critical about certain details.
Now that this house has minisplits, I would _increase_ the winter set temp?! No. What happens is certain inefficiencies that are perhaps beyond or at the edge of ideal design conditions, how that affects energy usage, AND most importantly what a consumer pays out of pocket.
When Wisconsin winters really hit, so 5F and below, the minisplit is pulling 3kw/h. I know because smart folks here & there recommended installing a whole house energy monitor. Do you have one installed yet? If you want to really get at where the electrons are going, monitoring a line is the only way. I went with IotaWatt and it's great. Anyways, back to minisplits in winter ...
The design spec for my unit is reported to be 1.76 COP @ 5F (technically it is a multisplit unit). More to the point, it is struggling to maintain a 68F set temp. Folks install minisplits in cold climates like ours and I'm only being critical of the reality for the cost. Can it heat? Yes. Is 5F or below an ideal design temp? No, it's an outlier. So COP goes down in cold climates, big whoop -- ah, but the cost to run them goes up as the COP goes down. 1 week of frigid cold and you're paying 3kw/h x 24hrs x7. Have a harsh winter and ... obviously it adds up.
Living in California, you would probably not face this inefficiency with a minisplit. I just want to bubble up the reality of costs.
Yes. I get some of the basic ideas you have iterated.
The original comment that spawned my query was actually based on someone living in California, so that's why I was interested. I totally get that lining in an area where the costs vary so significantly, as does the temperature range, that these considerations become much more polarized.
My comments were a genuine attempt to understand the situation of being in California and having that experience. Especially given changes such as ... Did I switch from "glow red" electric hot water to heat pump HW? Yes. ... which, on paper at least, should be a clear, huge win for costs.
Also, a point of correction for the comparison of the pellet stove example ... don't forget that pellet stoves actually need electricity to run, and measures of efficiency (on PG&E mind you) of that showed me that anywhere from 10-40% of the running costs of MY pellet stove, were the electricity costs. Yes, $6 a bag of pellets but a fair few kWh of electricity per day to boot.
Thanks for the comments.
Likewise Alex, I'm genuinely interested ... how do you explain your higher electricity bills? What difference are we talking 5% or less or are we talking 20% or more?
Have you changed habits because of the change to electric appliances? For example, do you run your heat at a higher temperature, more consistently/more often?
I would be interested in specifics too, especially since insulation retrofitting was mentioned.
If a DER or such was performed and going to electric still cost more in operating costs than NG, something seems suspect, or the electric rate to gas rate disparity is much higher than I realized.
I suppose it's mostly the latter. Gas is cheap by god.
I like the idea of going all electric for a variety of reasons, but I've wondered about the actual "greenness" of it in terms of fuel use & emissions. If you can install solar to cover all your use, great, but if you're pulling electricity from the grid it's going to be coming from mostly coal and gas, at around 30-35% efficiency. Locally burning gas for heat in, say, a condensing boiler or furnace is going to be fuel utilization at 95%+ efficiency. It then comes down to the COP of your heat pump -- Do they maintain a COP > 3 in winter conditions in northern zones?
Jonny, I think fuel use and emissions are going to be highly dependent on where you live. Most people in California are going to be getting less than 15% of their electricity from natural gas + other fuels (PG&E looks like they have almost no coal in their power mix) and some utilities like PG&E allow you to elect to purchase all your power from solar.
So, for those of us in places like Wisconsin where coal represents something like 35% of electric generation (16% nuclear, 8% biomass/hydro, and the rest mostly gas) does electrification make sense? e.g. I need to replace a water heater, should i get a heat pump unit?
I live in Wisconsin too.
If you mean the "greeness" of it, all electric makes sense when coupled with onsite generation. That's what I did. It also lowers your utility bill. :)
Something to keep in mind is the electrical grid will almost certainly continue to have decreasing carbon intensity. As renewables continue to come down in price, more and more of the grid supplied electricity is coming from these sources. Natural gas can be blended with green hydrogen, but there are a variety of pitfalls that will still need to be addressed making cleaner natural gas much less of a sure thing.
90% of my electricity comes from NG, at close to 40% once it hits my home (new higher efficiency plants). Combined with the pricing structure that equates NG in my home to a COP of 4.9-5.1, no heat pump will compete and be cost effective.
The only way electrification can happen is if as a society we seem fossil fuels unnecessary, and that historically has been driven by market demand and innovation (read $$).
"Feel good" isn't going to sway the masses.
+1000 Craig.
Market demand for hot tubs is created by people wanting to 'feel good'
The correct spelling is President Reagan, although Raygun is popular among some... :-)
A lot of people think Regan was calling the shots during the second term. ;-)
Sorry, but I can't get over the placement of the heat pump in front of a big view window. Who thought that was a good idea?
Jon,
It was either the architect, in which case the architect made a design error -- or else the architect failed to finalize the heating system details until it was too late, in which case the architect made a different kind of mistake.
Yeah, good luck cleaning those coils, quarterly. My Chiltrix unit required min distance is at least 12" , to back of unit.
My house is all electric, save for a pellet stove, and one hybrid vehicle ( one 2020 Chevy Bolt, all electric, at least 250 mile range). I have done most of the install myself, except for some things that required a licensed electrician, such as the backup heater, the 240V feed for the heat pump, and we did a heavy up to 150 amps, and the charge unit for the Bolt. I don't have cost figures yet, but I will be gathering that.
The Chiltrix is great, but it has taken quite a lot of massaging to get it to work right, including several relays that went bad out of the box, and the system pump which failed in the first year.
I am in Maryland, 2,250 sq ft 2 1/2 floor bungalow ( including basement), built in 1923; walls blown w/ fiberglass R 13 ; ( attic R 19 , working on that) ceilings at goal of R57 ( more than 50% achieved) rafters at R38; Hurd windows, and InSoFast 2" basement insulation ( 80% achieved)
I don't have audit data handy, but the house feels pretty tight to me, even though we are nowhere near needing an ERV or HRV.
Well written article Scott. The diagram of the electric panel is unique.
As a homeowner whose gone down the conversion to All Electric, I've found the cost is still higher than what many consumers will pay. Going down the "electric is cheaper" argument is full of pot holes, and money wasn't my motivation. I wanted to get away from fossil fuel dependence.
There's a lot of culture that we will be facing. Example: all the chefs on these home cooking shows & books are seen with gas ranges. Gas is "cultured" into us, whether for cooking, heating etc.. I was reminded of the old All Electric craze back in the 50's when a black-and-white original of Julia Child's TV show re-ran -- Julia was cooking on an electric range! Hah! That aired before my time but reading up on the history I found that the electric ranges were seen as the "clean" way to cook because the old gas ranges of the 20s and 30s were "dirty". My, how we've come full circle.
Let's Do the Time Warp Again!
That's a great insight on using cooking shows as a channel to get the word out about induction cooking.
vaportranz,
Two of my chef friends teach in the cooking programme in area high schools. The kitchens they use all have induction ranges. I suspect their graduates will be part of a cultural shift to electric cooking among professionals.
That is awesome to hear Malcolm. The next generation will do a ground up change in kitchens. I know a few folks who switched to induction. (I still cook on GE Calrods ... but will admit the burners look old fashioned.)
Justin
If you look on the Whirlpool site, you can no longer purchase an induction range. They were available in December but not now. They seem to have discontinued them.
You can purchase an induction cooktop, and you can purchase an induction range in their Kitchen Aid (higher priced) line.
Some observations:
1.) Electric costs go up after adding more electric equipment. In North America, on average, the cost of electricity (or propane) purchased from a utility is approximately 2-1/2 times the cost of natural gas.
2.) If it costs more to heat your house in San Francisco with a heat pump, just imagine what someone in Minnesota says after they switch from natural gas! I didn't even know you needed heat in San Francisco :)
3.) Solar panels don't generate power when they are covered in snow. Welcome to my world.
4.) Even without snow, solar power generation from November through February is essentially useless in northern regions of the continent.
5.) Providing enough battery storage to completely rely on solar power, especially during that winter period, is absolutely not financially viable at the current time. Including the public utilities.
6.)The current technology/cost of battery storage is THE number one problem with solar power generation, electric vehicles, etc.. Fortunately, we have some smart people at Tesla and Google working on it.
7.) When you calculate the cost to add solar to your home, don't forget about the cost to replace all of your batteries every 5-10 years, depending on type (lead acid vs. lithium) and how well you manage them. This adds significantly to the cost of solar.
8.) I am a big fan of solar power, but there are still some major obstacles to overcome.
9.) I absolutely disagree with inventing false "taxes" such as carbon charges to force people to a more expensive way of living. Better to work out the technical issues and reduce the costs of the alternative energy first. Let people decide for themselves if and when it's worth paying more to use one type of power or another. IMHO.
Re 1.) and 2.)
If your electric is only 2.5 x the cost of natural gas (per BTU? where is this??) a heat pump with a COP of 3 is cheaper to run than a gas furnace, especially as they run at maybe 95% efficiency.
Therefore, someone in Minnesota should say "thanks"!
In the southeast, it actually is common for the raw ratio to be about 2.5. I recently collected those numbers for 2019 (latest data I could find) and it's 2.4 in Gerorgia, 2.44 in Alabama, 2.59 in Louisiana, 2.69 in NC, and 2.7 in Arkansas. Even lower in Florida. In those states the heat pump COP is so high that heat pumps would make sense even with lower natural gas prices, so there are places where heat pumps easily win on current fuel costs alone.
If you're going to localize the ratio of electric to gas, another factor is the ambient temp and set temp for minisplit/heatpump COP.
To say the unit's COP = 3 when running these #s is disengenuious to consumers. The COPs are directly affected by ambient temp and set temp, and so the rated COP varies, especially by climate. For the #s junkies, this is made really clear by NEAP's database of units: https://ashp.neep.org/#!/product_list/
My unit is 1.76 COP @ 5F ambient when the set temp is 70F, and 3.11 @ 95F ambient. Ah, but devil in details: that nice, efficient cooling COP assumes the user has their set temp at 80F!
Who has a set temp of 80F in summer?! Hah! Even with ceiling fans giving us evaporative cooling, 75F set temp is the max before folks in my home get uncomfortable.
Some COP rating #s thrown out in the wild sound to me like the MPG ratings for cars: the EPA tested cars driving on "highways" at 55MPH and A/C off, or some unrealistic setup like that. Few people drive like that on an interstate during a hot, humid summer day (I noticed Texans drive 90MPH on their interstates!). The MPG #s look great but were unrealistic. And yes, I know the EPA adjusted their testing, and certain types of drivers can even beat the rated MPGs. But there's folks who complain theirs are worse still. Is it the driver? the car? the oil used? the climate? All are factors.
For home heating & cooling ratings, we have to be a bit more precise & transparent when comparing these fossil burners to minisplits. One great way is to collect data.
Yes, average COP will be different in different places, which is why I pointed that out in my comment.
Your observations are very similar to mine T_Barker.
1) smart folks will say the energy sources & utility bills must be normalized, so convert BTUs to Kwh, so this could be a red herring
2) yup, so a person's climate determines a lot of the efficiencies that tech can deliver
3) and when we raise this criticism, folks say "just clear the snow". Hah! Homeowners won't be climbing roof mounted solar in winter. I went with ground mount so I could sweep off the snow, but not every lot has enough room for it.
4) yup, and with roof pitches or ground mount pitches, the angle could be wrong. When I asked my installer why the angle of our ground mount wasn't closer to 45deg, he said "the panel mount manufacturer won't warranty that angle because of wind risk". Ahah. More devil in the details.
5) yup, our quote for batteries was huge, and there's no incentives to install batteries AFAIK
6) Enphase is also working on house batteries. Also, some smart folks have thrown out the idea of EV cars being the house battery backup! Nice, but I'm not going to hack our car to get that done. It must be supported & warrantied for the kind of capitol needed.
7) Yup. I follow full-time RVers who've been living through the lead acid to LiOn change for their "tiny house", and one couple just replaced their LiOn at the 5 year mark IIRC. ROI takes a hit when the tech doesn't last long enough to live out the projected savings.
8) Totally! I had solar installed b/c I _do_ believe they are one way to get at All Electric! What we're talking about here is construction criticism.
9) Sounds like can-o-worms :)
Justin
There's a difference between 'inventing taxes' (is there such a thing as a tax that is
naturally born?) and pricing in externalities; though I understand it may just appear as a difference in phrasing, and in either case it will be equally unpalatable to certain folks. For sure it's difficult to say where the external cost burden lays or how much it is, though that doesn't mean it isn't real and significant.
Across Canada for sure. And I've looked at numbers throughout the US as well. Obviously they vary, but 3 x is the worst I've seen.
You may want to dig a little deeper on the heat pump COP. I'm all for heat pumps, but from what I can gather from real world results (not manufacturer published optimums), in colder climates the average COP is probably closer to 2 on an annual average. And closer to 1 throughout the dead of winter. Especially in places like Michigan, Minnesota, Montana, etc.
If I was building a new build in a cold climate in a location that had natural gas, it would be a hard sell to get me to go with a heat pump.
T.,
To be clear, I am agreeing with your point that it is cheaper to heat with natural gas than a minisplit. Where I live, both natural gas ($7.55/MCF) and electric ($0.11/kWh) are cheap, but electric is 4.4 x more expensive. From a simple cost perspective, it's a no brainer. Of course other considerations could come into play. My point was that if electric is only 2.5x more expensive, the average heating costs might be a wash, depending on real-world efficiencies.
+1
I put a link above to NEEP's ratings of units to emphasize -- not the manufacturer's rating, but -- that even "lab" tested COPs are clearly affected by: ambient temp, and set temp. Perhaps there are even more factors at play, but it's already disengenuious to say "the COP is 3".
About real world efficiencies: one way is to collect data for units in production. Maybe real-world won't be as bad as you suspect, like COP 1 for cold climate, ... or maybe it will. We wouldn't know until data is collected from consumers.
https://ashp.neep.org/#!/product_list/
If you think I said "the COP is 3" you did not read my post. I presented a simple way to estimate relative costs for different heating systems. We all know COP varies with temperature, but if someone is trying to decide whether to go " all elctric" this kind of simple analysis is a useful tool. Sure we should collect data for every heat pump in all climates. But in the meantime, people are trying to make important decisions that can be guided by analysis.
The NEEP data are more useful than the published HSPF numbers, since the HSPF test requires locking the inverter to 60 hertz, whereas in the real world operation modulating inverter drive systems will vary the frequency to what works best for that particular system under the real-time conditions.
Selecting the right equipment for both the climate and the design load can often beat the HSPF assumptions on average COP, even in colder climates.
It would be straightforward to estimate a time-integrated COP using the NEEP data for a particular piece of equipment, along with heating degree day data from one's locality. The result could be further refined using estimated heat losses (manual J) from the area of the house served by the minisplit. I wonder if this has been done? Data from the model could be checked against actual electricity monitoring data for the given locale and equipment. Might be a fun project.
You raise a valid point, but your numbers are overly pessimistic. Let's take a look at Michigan. A typical design temperature there would be 0F. I just went to the NEEP product listing and randomly selected LG as a brand, and looked at 12k heat pumps. They have several models with COP of almost 3 at 5F, and there is very little dropoff from 17F down to 5F. So it's highly likely that the COP is still well above 2 at 0F. And remember that the design temperature, by definition, means only 1% of the total time is spent below that temperature.
So while there may be places where you can't get a heat pump above a COP of 1 throughout the dead of winter, none of the places you listed are among them. Maybe Antarctica. Even in Fairbanks Alaska, with a mean January temperature of -8F, you can find a heat pump that will handle that with relative ease.
COP of 3.38 at –15°C / 5°F, at 120% of its rated capacity.
That is what Mitsubishi Electric's most efficient mini-split appears to be capable of:
https://ashp.neep.org/#!/product/34425
While some air-source heat pumps are adequate for cold climates, for really cold places, ground-source heat pumps would likely be preferred.
GSHPs are more expensive to install but maintain high COPs in all climates.
My last electric bill was $157: heat pump including DHW, induction stove, and electric car. No dryer, 2 adults, single family house as above; of course, no gas bill, or methane seepage, either.
Average temperature 36.93*, I think.
https://www.wunderground.com/history/monthly/us/va/arlington-county/KDCA/date/2021-2
Heat pump is Chiltrix air to water 3 ton, CX34. The Psychrologix would work a lot better in my opinion if they just put a timer on the touchpad unit light. It runs all the time and skews the temperature and thus humidity readings of the room, by about 5* F. We keep it covered with a post card taped to the top; we don't want to look at that 24 hours a day.
https://www.chiltrix.com/documents/Chiltrix-Compare-IPLV-Chart.pdf
https://www.chiltrix.com/documents/Chiltrix-Psychrologix-TS.pdf
$157 is very good for 36F in February, IMO. What's your electric rate?
$220 here @ $.11/kw (though a daily fee is added that's ~$.5-1/day, so the kwh I paid for this time is really $210)
Wunderground from the local airport says our avg temp in February is 17F, and that's just a few degrees off from my utility's temperature (my utility provides the avg temp during the billing cycle -- 15F for Feb bill). Most Jan & Feb temps here in Wisconsin stay below freezing, so even though a utilities billing cycle isn't on the 31st of the month, like the weather history is, the Jan temps in that bill are about the same so it's probably not a huge difference for you either.
Your house envelope sounds better than ours despite similar builds, so I wonder how much of the electrons are going to my lower COP Bryant multisplit compared to your Chiltrix or seaping out of my old house compared to your better insulated house.
My house: 1700 sq ft, 2 stories, unconditioned basement (not included), 1930s build, closed-cell spray foamed rafters (so around R28 added), sealed basement ceiling, original side walls (so R3.5 or maybe more), 2-pane windows. Multisplit is 36k BTU w/ 3 heads, 50gal HPHW, 1 fridge & 2 freezers, electric dryer (EnergyStar stamp ... though it's an energy "hog", LOL!)
2 inputs make my calculations complex: I also charge a car, PHEV Chevy Volt, and have 8kW solar. So it takes more # crunching to remove the car and solar from the envelope equation -- aka, just the house please. The Bolt has much large batteries to charge than my Volt, but you may have similar commutes and not charging from empty. We charge from near empty most days, so that's 388kwH for February (according to my IoTaWatt for Feb billing cycle). Do you have solar?
You'd think my bill would be closer to yours, assuming the electric rates aren't very different.
In our most recent billing cycle, spanning 23 November through to 22 January, we used an average of 27.2 kWh per day (53 year old, 2,700 sq. ft. Cape Cod, CZ5A). All-electric, except for our propane dryer.
This winter, prior to March, had been quite a bit milder than most. December's average temperature was 3.0°C and January's -1.1°C. Our two ductless mini-splits are thirteen years old Sanyo KHS1271 with an HSPF of 9.3. Their replacements, upon retirement, will use one-third less energy.
That's not bad, given that I had a $200 gas bill for stove/HW/boiler to serve radiators in the same climate! (and then $40 electric bill, which includes dryer)
About those 120-volt heat-pump water heaters:
After Steve Knapp raised questions about the availability of these water heaters (see comment #3), I contacted Redwood Energy for clarification and also contacted the manufacturers directly.
Emily Higbee, Redwood Energy's research director, said in an email that the Rheem 120v water heater will be available for purchase by special order in April. According to Higbee, models from Bradford White and A.O. Smith are currently being field tested but are not yet available.
Rheem, through a spokesman, said: “Rheem has many products that are in development and designed to address evolving market needs, but does not currently offer a 120v solution. We will share more details on these new products and specific features as launch dates approach.”
GeoSpring is a little more complicated. GE halted production of its GeoSpring heat-pump water heater early in 2017. Bradford White bought the production equipment and continued making the water heaters at its Michigan factory, selling them under its AeroTherm label.
Asked about the development of a 120v heat-pump water heater, Bradford White said through a spokesman: “No, Bradford White does not offer a 120v AeroTherm heat-pump water heater. Like many other heat-pump water heater manufacturers, Bradford White is constantly exploring ways in which to enhance its heat-pump water heater line, but there is no release pending of a 120v AeroTherm.” In the email, the spokesman added, “This tells me there may have been a simple miscommunication somewhere down the line regarding [the] possibility of the product coming soon.”
A.O. Smith did not respond to emails asking for information.
I've edited the article accordingly.
So in summary, there aren't any. And Redwood Energy has no idea what they're talking about.
There's an upcoming webinar that is relevant to this discussion.
The Retrofit-ready Heat Pump Water Heater: 120 Volts to the Future
https://mailchi.mp/2addaf186be9/the-building-decarbonization-coalition-webinar-series-presents-residential-building-electrification-cost-effectiveness-with-amber-mahone-of-e3-1087460
May 13, 2021 from 10am - 11:30 AM PST
"Tom Zimmer (GE), Arthur Smith (A.O. Smith), and Kevin Clark (Rheem) will unveil a new generation of ‘Plug In,’ HPWH devices, which are compatible with current residential electrical systems. Requiring just 120 volts and low amperage, this exciting new class of HPWH eliminates the need for most electrical panel upgrades. Their ease of use will help accelerate the use of clean energy appliances that are essential to decarbonizing our homes."
Hi Scott,
Thank you for digging deeper into the 120 VAC issue. It will be interesting to see how the new Rheem unit performs compared to the company's existing 220 VAC HPWHs.
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