3 Similar Homes Offer Energy Contrasts

TVA looks at how to cut power needs

By Anne Paine • THE TENNESSEAN • May 3, 2010

Refrigerator doors open and close. Dishwashers and showers run from time to time. Lights click off and on.

It’s a bit ghostly because no one’s home in the three almost identical houses in the Campbell Creek subdivision of Knoxville.

But the robotics-driven houses have wildly varying electric bills, from close to $7 a day down to $1. That’s because of how they were built.

The activities inside the houses are part of a research project by the Tennessee Valley Authority and others to develop the most cost-effective and easy-to-use home energy efficiency technologies for consumers and builders.

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“You buy a house, it’s got hardwood floors and granite countertops so it must be a good house, you think,” said David Dinse, project manager for TVA.

“These three houses don’t look any different from each other, but one uses less than a third of the energy.”

The public power producer is trying to figure out the best ways to cut electricity demand. That lessens the need for costly new power plants that rack up debt for ratepayers.

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The work fits in, too, with a nationwide interest in increasing energy independence and reducing pollution.

Buildings are one of the country’s greatest energy wasters, and federal data shows Tennesseans in a recent year used more residential electricity per person than any other state except Alabama.

What amounts to a TVA science experiment involved building three 2,400-square-foot, look-alike houses — each with a different level of energy efficiency.

A company constructed the base home for $244,800 with standard techniques. The second house was built the same, but afterward workers retrofitted it with energy efficiency features that resulted in about a
40 percent drop in electricity use.

The standard house costs almost $7 a day in electric utilities, while the bill for the retrofit house runs around $4 a day.

The third house — built with cutting-edge features and solar panels — is a near zero energy house, with an electric utility bill of about $1 a day.

The largest savings of the retrofit house over the first came from having the heating and air conditioning ducts and system inside the house. Otherwise, the system spends electricity fighting the extremes of cold and heat.

“We should just make it illegal in new homes to put heating and cooling systems anywhere outside the envelope,” said John Christian, building researcher with Oak Ridge National Laboratory, a partner in the project along with the U.S. Department of Energy.

“Why would we waste 35-45 percent of the energy?”

Putting in fluorescent bulbs brought a 21 percent savings over the base home.

The homeowner would actually save money — $35 a year — from the beginning if the retrofit project money were borrowed at 6 percent interest over 10 years and TVA incentives were used. The amount saved jumps to $1,000 a year after that.

Results ‘eye-opening’

Readings on energy use are taken automatically every 15 minutes in the two-story houses where simulations of family life take place, right down to running the washers and dryers.

Hundreds of monitors collect data on energy performance, as well as on temperature and humidity to gauge comfort.

The stainless steel refrigerators have a sign that warns “Caution: Refrigerator doors open automatically.”

Yellow-coated posts like giant arms hold the doors, ready to swing them open at those times when a member of a family of three might do so.

John Kerr, who built the three traditional-style, all-electric houses, called the project and its results “eye-opening.”

“Every house built today has insulation installed, but it only takes a little gap in the insulation and it’s like a window’s open all the time,” said Kerr with Michael Rhodes Construction.

Christian, the scientist who selected the technologies and oversaw their installation on the second two buildings, made the sites almost like a classroom.

“I had a pretty good knowledge of building homes inside and out,” said Kerr, a builder for 30 years. “After working with Jeff, I found out there are things constantly evolving in the energy field.”

Rather than having regular clashes with a “laboratory geek,” Kerr discovered he and his crews enjoyed learning new ways to build that don’t necessarily add costs, but increase energy efficiency.

While the retrofit home received about $9,000 in changes, $6,000 was for attic work that included insulating the top and sides of that area where the heating and air conditioning system is located. Putting the system inside the house’s heating and cooling envelope was a built-in feature with the third home.

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“Even if you build in a conventional method without trying to add these energy efficiency features, the most important thing about building today is caulking and installing your insulation properly and making sure you control air infiltration,” Kerr said.

Kerr framed the third house differently from the first two, and the added features — including about $13,000 in solar panels — contributed a total of about $30,000 to the cost. The extra cost, if paid for with a 30-year loan at 7 percent interest, would be about $35 a month for those years.

One would have a more comfortable house climate-wise and something of an energy insurance policy, Christian said. It’s likely that electric prices will rise in the future, bringing that extra $35 a month down.

Project to last until 2012

Different techniques will be tried in the houses TVA is leasing through at least 2012.

“We’re learning as we go with what we’ve installed and using that learning to guide further retrofits,” Christian said.

The houses will be sold when the project is over.

In the meantime, what’s it like to have houses with phantom activity nearby?

“They’re no bother,” said Bruce Loftis, who invited Christian to the July 4 neighborhood block party like he was one of them.

“The lawns get mowed,” he added.

Contact Anne Paine at 615-259-8071 or apaine@tennesssean.com.