Given a photovoltaic system with a capacity of as much as 8 kilowatts, does it make any sense to include natural gas appliances in a new house, or would an all-electric design be more practical?
That’s the question Markus ponders as he plans a new house in Houston, Texas. Although he has natural gas service in the house where he currently lives, the size of his new rooftop solar system could prompt a change of heart.
“It will probably be a ‘Pretty Good’ house — dense-packed cellulose and exterior rigid foam insulation with an encapsulated attic and targeting an ach50 of less than 3 with an ERV system for ventilation,” Markus writes in a Q&A post at Green Building Advisor. “I will have a sizable PV array on the roof — 6 to 8 kW — so I have been debating whether to use natural gas as in my current house for multiple appliances or go all-electric.”
Markus finds both pluses and minuses with an all-electric design. The benefits include avoiding a monthly $25 charge for gas; better air quality without the risk of backdrafting; the chance to use an induction range for cooking; using a heat-pump water heater to help cool the attic or garage; and not having to run gas lines around the house.
He does, however, point to a few disadvantages. Markus says electrical equipment is “more complicated and less reliable,” which could mean more repairs, and natural gas would give the house higher resale value. He likes his gas dryer, and points out that an all-electric house might be a problem in the event of a hurricane.
“Anything I might have not considered here?” he asks. “Anyone else had to make this choice in a cooling-driven climate? Anyone had bad experience with reliability of newer electrical units vs. natural gas ones?” Those are the questions for this Q&A Spotlight.
Electrical equipment is not necessarily problematic
GBA senior editor Martin Holladay commends Markus for his analysis, but he thinks Markus is off base in believing that electrical equipment is more prone to breakdowns than equipment using gas.
“It’s simply untrue that ‘electrical equipment is more complicated and less reliable’ than gas equipment,” Holladay writes. “I’ve had a balky gas-fired tankless water heater from Bosch that has driven me crazy for years — it has a pilot light that doesn’t want to stay lit. Makes me wish I had a dumb-as-a-rock electric-resistance water heater.”
Nor does Holladay understand Markus’s preference for a gas clothes dryer. After all, Holladay says, “when you open the door, the clothes are dry, no matter which fuel was used to dry them.”
There is another reason that an all-electric design is sensible, Holladay says: “Green builders who look at our current climate crisis, and who want to be part of a global transition away from fossil fuels, generally lean toward all-electric homes equipped with PV.”
Installing gas as a hedge
Anon3 thinks Markus should go ahead and run gas lines even if he has no intention of using natural gas. If natural gas lines are installed, the house will be worth more as a resale. “Just don’t use it yourself,” Anon3 says.
Gas will not only make the house more valuable, Anon3 says, but it’s difficult to add after the house has been built. “The inability to have a gas oven can often be a deal-killer for high-end homes,” he says. “If this is a $100,000 house, you don’t have to worry about this, people expect electric-only at this price point.”
John Clark agrees: “Gas hookups will expand your pool of potential buyers, especially if they don’t want the PV array on the roof,” Clark says.
Stephen Sheehy thinks otherwise. “I disagree with Anon,” Sheehy writes. “For resale, people want to be comfortable. They are less likely to care about what fuel keeps them comfortable. Skip the cost of running gas pipes all over the place and build a nice tight house, well insulated, heated and cooled with efficient heat pumps.
“Just my opinion,” Sheehy continues, “but I think it makes no sense to spend money installing features you don’t want, because some future buyer might want them. If it makes sense to use minisplits for heat and AC, installing ductwork for future gas heating, cooling, and cooking doesn’t make sense.”
Malcolm Taylor adds that people buy houses for a variety of reasons, but he can’t imagine a buyer passing up an otherwise attractive house because it didn’t allow switching energy sources in the future. “I bet the absence of a walk-in closet in the master bedroom has more effect on the marketability of a house than gas stub-outs,” he says.
Think twice about a heat-pump water heater
As load management on the grid becomes more sophisticated, consumers may reap some financial rewards from “smart” or “grid-aware” appliances, suggests Dana Dorsett. Plus, conventional water heaters are simpler in design and have fewer moving parts than heat-pump water heaters (HPWHs), making them a potentially better investment.
The wild card in this equation is whether ERCOT (the Electric Reliability Council of Texas, which manages the regional grid) can offer financial incentives to homeowners.
“So far, ERCOT doesn’t have a capacity market to bid into, but high value frequency and voltage stabilization services are there,” Dorsett says. “One such aggregator operating large fleets of residential water heaters as a ‘virtual power plant’ in the PJM grid region is Mosaic Power.”
Because Texas has some of the most creative electricity markets in the country, Dorsett says, someone will be figuring out a way to make money with aggregated distributed resources.
If Markus does choose a heat-pump water heater, Dorsett adds, he would be better off installing it in a conditioned attic rather than in the garage.
“Installing the HPWH in the conditioned attic is better from a whole-house efficiency point of view than putting it in the garage,” Dorsett says. “A better-than-code house with a high SEER cooling system in Houston will have excess latent load to deal with. Installing the HPWH in the attic, inside the pressure boundary of the house, reduces the latent load, directly converting it to sensible heat inside the insulated tank, whereas a dehumidifier delivers it as sensible heat into the room air, raising the cooling load.”
Not cooking with gas
Kitchens and kitchen appliances are typically a key selling point in any real estate transaction, but Sheehy doesn’t see any particular advantage to gas ovens or gas ranges.
“I’ve never met a cook who prefers a gas oven to electric,” he says. “And once they use an induction cooktop, they all prefer them to gas.”
Michael Maines, who has designed a number of high-end kitchens, finds that people who actually cook in their own kitchens prefer electric convection ovens. “They have finer control and more even heat than gas ovens,” he says.
Maines also recommends induction cooktops, although he’s had trouble convincing cooks (including his wife) to give up their $1,000+ investments in All-Clad cookware in order to save $10 or $20 on energy use in a year.
Non-metallic pots and pans won’t work on an induction range, but as Sheehy points out that some All-Clad and its clones will work just fine, as will cast iron. (All-Clad’s MC2 line is not magnetic, Maines adds, so the test that Sheehy suggests is probably good advice: “If a magnet sticks to it, it’ll work.”)
Our expert’s opinion
GBA technical director Peter Yost adds these thoughts:
Great discussion, and the sidebar points to some equally useful past GBA articles for this topic. Just a few additional points from me:
All-electric vs. incorporating natural gas: Moving electrons around in a house just seems inherently easier and safer to me; eliminating open-combustion devices is always a wise choice. And with grid-tied PV, those moving electrons are literally a mobile and self-regulating currency for all your energy needs.
Long-term performance of heat-pump water heaters: How many times have HPWHs been introduced to the marketplace? How complicated is it to assess their performance? Should a heat pump be dedicated solely to producing domestic hot water? I sure hope that this time around that HPWH energy performance and service life rise to the occasion, but even if I lived in a mild climate, I would be putting my dollars, time, and head-scratching in other parts of the building.
Induction cooking performance: I am not a chef or even a day-to-day cook, but it would be nice to put this issue to rest. For more on that, see these articles on induction cooking: from The New York Times; from Treehugger; and from Daily Meal.
If we could get every home cook to run a CO2 monitor and hygrometer when they fire up their gas burners, the invisible costs of cooking with gas might become more apparent. That could help make a stronger case for induction cooktops.