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Advocacy group SWEEP cites evidence for big shift from gas


by Allen Best

It’s happening in Colorado, not in a way that will bowl you over just yet, but with just enough evidence to cause the Southwest Energy Efficiency Project to proclaim the state is “on the cusp of a market transition” to all-electric in new homes and other buildings.

A recent survey by the Boulder-based non-profit advocacy group delivered 11 examples that include housing projects in Fort Collins, Denver and Pueblo, plus a school in the San Luis Valley. There is also an employee housing project in a suburb of Aspen, and individual homes near Grand Junction and in the foothills west of Arvada. None have connections to gas, either propane or natural gas.

Christine Brinker, of SWEEP’s building efficiency program, says the marketplace appears to be fast evolving.

“We keep hearing rumors of housing developments that are planning to be all-electric but just aren’t far enough along to announce publicly,” says Brinker. “We got the impression that if we were to do the same survey in one or two years we would find a lot more than we have now.”

This is not the building electrification of the 1970s or 1980s, which left a sour taste—and depleted bank accounts—for many. Builders may be acknowledging that history by marketing all-electric homes with terms like sustainable, high-performance, or net-zero more instead of “all electric.” SWEEP also found sparse mention of the specific technologies being used to avoid fossil fuels.

Ground-source heat pumps employ coils 5 to 15 feet below grade, drawing on the steady temperature of about 55 degrees at that depth found in most places of Colorado. This steady temperature can be milked to provide warmth in winter and cooling in summer.

Air-source heat pumps can do the same thing, but with units typically just outside the building, extracting heat from outdoor air and moving it inside (or vice versa in the summer months). Both are powered with electricity, and both use refrigerants to compress and concentrate the heat. Air-source heat pumps can be installed at less cost, because they require no earth moving, but perform less efficiently than ground-source heat pumps. There are examples of both types of systems in the SWEEP report.


Utility rebates and a grant have helped the Aspen Skiing Co. defray the higher cost of alternative technology at its Willits Workforce Housing project in Basalt. Top photo, Healthy indoor quality is a selling point for Thrive’s 37 all-electric homes in Denver’s Center Park neighborhood.

Developers, architects, and others consulted by SWEEP almost all cite healthier indoor air quality in making the choice to provide all-electric buildings.

Healthy indoor air is a key component of the Thrive brand,” said Bill Rectanus, vice president of operations for Thrive Homes, which has 39 all-electric homes in Denver’s Central Park (formerly Stapleton) neighborhood.  The homes list for more than $700,000. “Burning anything in your house releases carbon dioxide and other pollutants into the air you’re breathing, and reducing the levels of those contaminants at home is essential to creating a healthier indoor air environment.”

Most developers also cite a desire to reduce emissions into the atmosphere.

Still another selling point is more abstract, but overlapping with the intent of reducing atmospheric emissions of greenhouse gases. “New homes are built to last for many years and should use future technologies,” said Norbert Klebl, developer of Geos Neighborhood, a multi-housing project in Arvada.

“Not building to zero will be building to obsolescence,” says Sue McFaddin, president of Seven Generations, the development consultant for Revive Homes. Revive consists of 37 duplex homes of up to 2,500 square feet and also 18 townhomes in Fort Collins that use primarily ground-source heat pumps.

Economics of these technologies make sense in the long-term in every case. They can also make sense in the short term.

“You can get great savings by not running gas lines,” says McFaddin.

“All electric makes a great deal of sense from both a development and environmental perspective,” she adds.

This is from Big Pivots, an e-journal covering the energy and water transitions in Colorado and beyond. To get copies, sign up at

On the northeastern outskirts of Pueblo, in the emerging North Vista Highlands development,  roads are now being graded amid the sagebrush for 162 lots for single-family homes of up to 2,600 square feet and townhomes of up to 2,400 square feet. Rod Stambaugh, president and chairman of Sprout Tech Homes, says highly efficient homes with very low energy costs will cost less over the long-term term if you consider the total cost of home ownership. And, as do all others, he cites the better air quality.

The Aspen Skiing Co. is going all in on all-electric. It was a participant in Basalt Vista, a project of 27 duplex homes in Basalt, located 18 miles from Aspen. Now, it has pulled the trigger on Willits Workforce Housing Project for the company employees and community child-care workers to rent.

The 43 units at Willits will altogether have $70,000 higher costs for heating as compared to high-efficiency natural gas furnaces. This is being defrayed by $58,000 in rebates from the local utility, Holy Cross Energy. The Community Office for Resource Efficiency also gave the project a $100,000 innovation grant.

The high school in Blanca will have not be built to Passive House standards and will have no propane, as the existing school does, nor natural gas.

The most unusual project is a school at Blanca, which lies at the foot of the eponymously named 14,344-foot peak in the San Luis Valley. The 86,000-square-foot school being completed this year will not use propane, as the existing school does. That saves the district money and headaches, as in rural areas it can be harder to find technicians. Instead, the school will have an improved envelope, built to Passive House standards. That costs more, but is offset by the simplified electric heating. The school district calculated no added cost for the all-electric design.

SWEEP also profiled several single-family homes. Like the school in the San Luis Valley, some otherwise would most likely use propane, which comes at higher cost than natural gas.

“We found that propane is where all-electric really makes sense,” says SWEEP’s Neil Kolwey, a co-author of the report.

Unlike new construction, use of these new technologies in existing homes can be less cost-effective, says the team from SWEEP, especially if the home uses natural gas.  If replacing propane heating, adding a heat pump will definitely reduce heating costs.

There are considerations. Gas-fired furnaces produce air at about 120 degrees F. Heat produced by air-source heat pumps comes out of registers at 90 to 95 degrees. “So, you need to move more air with a heat pump. If you try to do that with the same ducts, it will be really noisy,” says Kolwey. But replacing ducts can get expensive. “So in that case, you would use the heat pump to displace some of the gas consumption, at the milder outdoor temperatures, but keep the gas furnace for the colder temperatures.”

SWEEP’s survey was not necessarily exhaustive but was instead designed to highlight some examples and highlight some of the benefits.


Norbert Klebl, developer of the GEOS net-zero project in western Arvada, says =new homes are built to last for many years and should use future technologies.

Colorado has lagged behind the Southeast and the Northwest, both less inclined to cold temperatures, in embracing alternatives to gas combustion in buildings. Air-source heat pumps have improved significantly in recent years and can now provide heat for buildings even when temperatures outside plunge below zero. One new home in Fraser, not known for its mild temperatures, has air-source heat pumps that deliver at least warmth to the interior of the house, if at diminished levels, even when temperatures have fallen 15 below. Homes in colder climates, however, will want backup electric heating supplements.

One concern has been whether there are enough technicians trained in the new technologies. “The cost of installing a heat pump varies pretty widely because many installers aren’t entirely comfortable with them,” says Brinker. She reports discussions among utilities and others to elevate the workforce.

Tri-State Generation and Transmission, which supplies electricity to 18 of Colorado’s 22 electrical cooperatives, has had one training session and plans a second. La Plata Energy and Mountain Parks Electric, two of the member cooperatives, have robustly begun to encourage the new technologies.

Xcel in November 2020 issued a position paper that urged caution in pushing electrification of homes and other buildings too rapidly. For example, it warned of many problems, such as situations where lower-income customers might be left purchasing natural gas—at higher costs—even as higher-income customers in the same general area convert to electricity. The report also suggested that the technology isn’t quite ready for prime-time, at least in Colorado, even along the Front Range.

Environmental advocates insist the technology has arrived. As for moving too rapidly, SWEEP and other groups point to the 2050 target of 90% economy wide carbon reduction adopted by Colorado in 2019.

There’s no risk that this will happen tomorrow. “It’s a gradual process,” says Brinker.

But the process, says SWEEP, should begin sooner with new construction. There is no evidence, however, that the big major production builders who build the majority of the 40,000 new homes annually being built along the Front Range have imminent plans to move to electrification of homes, as have some done in California.

Allen Best
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