BLOOMBERG – The future is looking electric as a growing roster of cities bar the use of natural gas in new residential construction in a bid to lower greenhouse gas emissions and meet climate targets. In just the past two months, San Francisco, San Jose, and Oakland, California have enacted gas bans, joining more than three dozen other municipalities that have done so since 2019.
New construction, though, is a small fraction of the housing stock. Homeowners can multiply the impact of gas bans by retrofitting existing dwellings when appliances reach the end of their useful lives, according to researcher Sam Calisch from Rewiring America, a California nonprofit that promotes home electrification.
That means replacing gas furnaces, water heaters, stoves, and clothes dryers with high efficiency electric versions. If your house needs a new roof, it’s the optimal time to install a solar-and-battery storage system to power those appliances with carbon-free electricity.
About half of houses in the United States (US) are heated by natural gas, so decarbonising homes promises to lock in long-term environmental and economic benefits. But the upfront costs can be high and the process complicated, as I discovered when I took initial steps toward electrifying my 1928 home in Berkeley, California.
First, determine if your home’s electrical system can handle the additional load from the new appliances. Electric devices called air-source heat pumps warm and cool your house, provide hot water, and dry clothes without burning fossil fuels.
Instead, they extract heat from the atmosphere and are up to four times more efficient than their natural gas counterparts. When the electric grid is powered by renewable energy, your home’s carbon emissions are further slashed.
The US Environmental Protection Agency (EPA) estimates that switching to heat pumps would save the average household hundreds of dollars a year in utility costs.
When a technician from a Bay Area company that specialises in heat pumps inspected my home’s electrical panel, he found that it was rated for 200 amps and could manage the addition of a heat pump and a heat pump water heater.
But he frowned when he opened another electrical panel connected to the utility metre box. It was rated for only 100 amps and must be upgraded to 200 amps. Also in need of an upgrade was the “supply wire” that connects the house to utility power lines.
Where I live, the utility must install the new supply wire, a process that can take a month or two. The estimated cost for a new panel and wire was an eye-popping USD5,850.
Calisch calls electrical upgrades one of the biggest hurdles to home electrification. “If your furnace goes out, no one in their right mind is going to wait 60 days for an electrical upgrade so that they can install a heat pump,” he said.
The lesson is to plan ahead and complete any needed electrical upgrades before your furnace and water heater are on their last legs.
Rewiring America estimates it would cost the average US household USD70,000 to completely decarbonise (including adding solar and replacing a fossil fuel vehicle with an electric one). That’s a prohibitive price tag for many people.
Non-profit Rocky Mountain Institute senior associate Claire McKenna recommends prioritising upgrades over time, beginning with heating and hot water.
“That’s where the bulk of the energy use is in a home and where you’re going to see the most savings,” she said.
Replacing a gas furnace is one of the more complicated upgrades. Your existing heating system will determine to a large degree the type of heat pump most suitable for the home.
If your home has wall-mounted gas heaters, then the best option probably is a so-called ductless mini-split heat pump.
The heat pump, resembling an air conditioning unit, sits outside the house. A copper coil filled with refrigerant absorbs heat from the surrounding air, which is transformed into a cold gas. A compressor pressurises the gas, raising its temperature. The warm air is distributed throughout the house through ventilation units attached to the walls of individual rooms.
In the summer, heat pumps cool the home by extracting hot air from inside the house and transferring it outside.
Most homes, like mine, have central heat and so a heat pump would use the existing duct system to distribute warm and cool air. Technicians from two heating companies inspected my furnace room that sits in a crawl space underneath the house. The bulky gas furnace would be swapped for an indoor air handler, also called a fan coil, which is about the size of a small box.
A heat pump would be placed outside the back wall of the house and would transfer warm or cool air through pipes connected to the air handler, which would then pump the air through the duct work and existing floor vents.
The bad news was that the old duct work had deteriorated and would need to be replaced by high efficiency new ducts that one contractor estimated would cost USD3,749.
That contractor priced a high-efficiency 30,000 BTU heat pump system at USD11,574. By comparison, my gas furnace was sized at 80,000 BTU. A second contractor recommended a 36,000 BTU heat pump system with a whopping installed cost of USD38,500.
It pays to shop around.
Installing a heat pump water heater is more straightforward but does requires additional plumbing and electrical work.
A 50-gallon heat pump water heater would fit in the crawl space where my gas water heater now stands.
The model recommended by one contractor was a hybrid electric heat pump equipped with a standard electric heating element to provide supplemental hot water if needed. It retails for USD1,300, but the extra electrical and plumbing work boosted the installed cost to USD4,600. The second contractor came back with a USD7,000 installed price.
Heat pump clothes dryers are relatively new to the US, but they’re 50 per cent more efficient than conventional electric dryers, the usual alternative to gas dryers.
Heat pump dryers operate in a closed loop cycle so they don’t require outside venting, though the moisture they collect must be piped to a drain.
They dry clothes at lower temperatures, which takes longer but leaves them softer and more wrinkle-free.
As with other heat pumps, they’re more expensive than gas dryers, costing USD1,000 or more.
Most people aren’t emotionally attached to their furnace, water heater, or clothes dryer. Gas stoves are another matter.
Resistance to municipal gas bans has centred on a reluctance to part with the familiar flickering blue flame.
Induction stoves are the latest cooking technology, and admittedly, they’re more Mr Spock than Alice Waters. But induction ranges are 40 per cent more energy efficient than gas ranges, which are also a substantial source of indoor air pollution.
Here’s how they work: Coils embedded in a ceramic glass surface generate a magnetic field that creates heat directly within cookware. Conventional electric and gas stovetops waste energy by heating the surrounding air. Prices for induction ranges start around USD1,000.
If you want to install solar panels and battery storage, there are well-established tax credits and rebates and a variety of financing options.
That’s not the case for home electrification and homeowners have to rely on a grab bag of state, federal, and utility rebates often restricted to certain brands and models.
In a report released in October, Rewiring America called low-interest government-backed loans key to accelerating home electrification.
Calisch and co-author Saul Griffith calculated that offering loans with a two per cent interest rate to decarbonise homes would result in savings from lowered energy costs that would far exceed the cost of financing and create millions of jobs.
“It’s a winning long-term proposition,” said Calisch.
The cost and complexity of a potential retrofit came as a bit of a shock. So was the range of the estimates I received, which showed me that I needed to obtain more bids and scrutinise them carefully.
I was also surprised that none of the contractors inquired about how well-insulated my 92-year-old house is, given that the size-and cost-of a heat pump needs to be calibrated to the energy efficiency of the home. Before I take any further steps, I’ll have an energy audit conducted and make any needed insulation improvements.
Doing a complete retrofit at once isn’t financially feasible so I’ll prioritise beginning with upgrading the electrical panel (after securing more quotes). I’ll be ready if the furnace or water heater suddenly expires and will have the electrical capacity to one day install an electric car charger and a solar and battery storage system.
Next would be retiring the furnace as it’s a substantial consumer of natural gas and contributor to my utility bill in the winter. My electric stove dates from the “Mad Men” era, so an induction range replacement is on the horizon and qualifies for a USD300 rebate.
The water heater is 15 years old but an inspection showed that it still has a few years of life left. The clothes dryer is a lower priority as I already use a solar-powered dryer for much of the year-the backyard clothes line.