As Ann Arbor aims to get off gas, some see promise in electric radiant floors

DEXTER, MI — Weighing options for heating the guest house they’re building behind their Dexter home, Katherine Becker and Steve Wells decided to go an alternative route.

Rather than gas heat, which is still the most common way to heat American homes, the couple recently installed an all-electric radiant heat system under the floors. Brass Tee Reducer

As Ann Arbor aims to get off gas, some see promise in electric radiant floors - mlive.com

A low-voltage STEP HEAT system, which cost them about $7,000, now quietly provides even and comfortable warmth for their 14-foot-by-35-foot, single-story guest house without needing a bulky, noisy and less-healthy gas furnace or forced-air system, which can be less efficient and less consistent.

“It works very well,” Wells said of the warm floors. “So far, it’s very nice. We’re pleased.”

STEP HEAT radiant in-floor heating is installed in an Accessory Dwelling Unit in Dexter on Thursday, Feb. 2, 2023.Jacob Hamilton | MLive.com

Local builder and solar installer Dave Friedrichs, whose company installed the couple’s 7.2-kilowatt solar array last year, suggested they consider STEP HEAT after he installed the same system for an all-electric community center and office he built for the Glen Oaks housing co-op in Superior Township in 2021.

Just like with his Dexter clients, the radiant floors at Glen Oaks now provide 100% of the all-electric building’s heat — no need to burn gas, said Friedrichs of Homeland Solar and Homeland Builders of Michigan. The center is designed to be highly energy efficient and with a large south-facing roof for an eventual solar array. For the heating system, the floor wiring comes down to wall-mounted power units in the basement.

Homeland Solar Owner David Friedrichs stands next to power supplies powering in-floor radiant heat at the new community center for Glen Oaks Consumer Housing at 1351 Stamford Road in Superior Township on Thursday, Feb. 2, 2023.Jacob Hamilton | MLive.com

As Ann Arbor and Washtenaw County aim for carbon-neutrality, a key strategy is electrifying buildings in tandem with moving to renewable energy, and Friedrichs thinks radiant heat floors can be a nice, economical alternative to ground-source or air-source heat pumps for going electric. Heat pump systems, though more energy efficient, can be more costly upfront, with perhaps the exception of ductless mini-split systems.

As Ann Arbor considers a ban on gas for new buildings, some have pointed out heat pumps can cost homeowners tens of thousands of dollars — potentially around $50,000 in the case of a geothermal system for a larger home.

Radiant heat floors, on the other hand, don’t have quite as big of an upfront price tag, Friedrichs said.

“It’s less expensive and it produces comfortable heat,” he said. “The technology is super.”

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Friedrichs said he’s trying to get some of the developers doing big projects in Ann Arbor to visit STEP HEAT’s headquarters in St. Louis to see the company’s 35,000-square-foot building, which was built to show how the technology can comfortably and efficiently heat even a large commercial building.

Missy Stults, Ann Arbor’s sustainability director who is leading the city’s carbon-neutrality quest, said all tools for moving to electric buildings need to be explored and if electric radiant floors can be done efficiently, that’s great and she’s intrigued.

STEP HEAT radiant in-floor heating is installed in an Accessory Dwelling Unit in Dexter on Thursday, Feb. 2, 2023.Jacob Hamilton | MLive.com

The U.S. Department of Energy endorses radiant floor heat, saying it has a number of advantages.

“It is more efficient than baseboard heating and usually more efficient than forced-air heating because it eliminates duct losses,” the DOE website states. “People with allergies often prefer radiant heat because it doesn’t distribute allergens like forced-air systems can.”

Because of the relatively high cost of electricity, electric radiant floors are usually only cost-effective if they include a significant thermal mass such as a thick concrete floor slab and if the electric utility company offers time-of-use rates, the DOE advises, noting time-of-use rates, which DTE Energy is implementing in March, can allow customers to “charge” the concrete with heat during off-peak hours overnight.

Electric radiant floors also may make sense for home additions if it’s impractical to extend an existing heating system into a new space, but homeowners should consider other options such as mini-split heat pumps, which operate more efficiently and also provide cooling, the DOE advises.

STEP HEAT radiant in-floor heating is installed in an Accessory Dwelling Unit in Dexter on Thursday, Feb. 2, 2023.Jacob Hamilton | MLive.com

The DOE also notes hydronic systems, which use heated water pumped from a boiler through tubing that can be laid under floors, are still the most popular and cost-effective radiant heating systems. They use little electricity and can produce heat multiple ways, including with gas-fired boilers or solar water heaters.

Becker and Wells have had hydronic radiant floors as the heat source for their main home for the past six years and say it’s very comfortable and economical, though it uses gas.

For their guest house, where they expect Becker’s parents and others to stay, they liked the idea of a system totally out of sight and figured electric makes sense especially now that they’ve gone solar. They’re also making their decisions with the climate crisis and sustainability in mind.

STEP HEAT radiant in-floor heating is installed in an Accessory Dwelling Unit in Dexter on Thursday, Feb. 2, 2023.Jacob Hamilton | MLive.com

“We’ve actually got the floor covering in. The whole thing is working now,” Wells said after recently finishing installing vinyl plank flooring over the STEP HEAT electrical wiring strips.

They designed the guest house — known as an accessory dwelling unit or ADU — to be highly energy efficient, with structural insulated panels and a concrete slab foundation that’s insulated from the ground and acts as a giant heat sink.

“It’s like an Oreo cookie almost,” Wells said of the six-inch-thick Styrofoam insulation in the house walls, noting it’s so well sealed it limits the electricity needed to keep warm.

“If you get into this whole world of energy efficiency, green energy, etc., a purely electric house is very energy efficient, and so we can get by with less than 3,500 watts of power to keep it toasty,” he said. “Also, we’ve got solar, so we’re using our solar system to cut our electrical costs overall.”

They also have an Emporia Vue power monitor and so far it’s showing the radiant floor system is mostly running at night and hardly uses electricity during the day, Becker said.

“It should be pretty maintenance-free,” she said. “You know how if you have a forced-air furnace you’re supposed to have them come and check it every fall? There’s nothing here to check.”

As Ann Arbor aims to get off gas, some see promise in electric radiant floors - mlive.com