Return to story

Saving, generating energy

October 23, 2009 12:58 pm

BY RICHARD AMRHINE

Just about everyone these days avoids wasting energy. Many people have taken steps to conserve energy. But very, very few people generate energy at home and sell back what they don't use to the power company.

That's what will happen at the house local builder Jeff Hall of J. Hall Homes is building just off Caledon Road in King George County.

The photovoltaic solar roof panels that will provide on-site energy production are only a part of the program that will make the house efficient to the point that it will be a "net-zero," or zero-energy, home. Other contributing aspects include the geothermal heating and cooling system, the advanced framing and sheathing techniques and the tankless hot water system, just to name the key elements.

"It's really a matter of education," said Hall. "Once people understand it, the question becomes, 'Why isn't everyone doing it?'"

He explained that in the case of this modest, 1,500-square-foot home he is building, the goal is to far exceed established energy-efficiency standards at a reasonable cost in a conventional-looking house.

"People get scared when you talk about how much something is going to cost," said Hall. "But when they understand the tax credits they can take and the amount of money they'll save over time, they can see the return they'll have on their investment."

In round figures, this J. Hall home would cost about $250,000 without the added energy-efficiency features, land not included. Adding them will raise the cost to between $280,000 and $300,000.

Hall said prospective buyers can calculate the cost of various enhancements versus the savings each is estimated to provide, then determine what items will be least cost-neutral over the course of a 30-year loan.

THE SOLAR SYSTEM

Key to the project is the 3.6-kilowatt photovoltaic system with solar panels attached to the roof. The roof itself uses new 50-year Energy Star asphalt shingles that incorporate an ingredient that helps them reflect heat away from the roof rather than letting it inside the attic. Though it doesn't apply to new construction, such a roof used as a replacement on an existing home would qualify for a tax credit.

Hall said the positioning of the house itself, and constructing the roof at a specific angle, will allow the panels to absorb the maximum amount of sunlight.

On sunny days, more power than the house needs will be generated, and the inverter, or reverse meter, will kick in to send the surplus power back into the grid, thereby reducing the owners' next utility bill.

Thirty percent of the cost of solar panels can be taken as a tax credit.

Derek McAvoy of Mid-South Building Supply Inc., which is supplying the German-made Schuco panels, said the demand for such technology is increasing slowly in the Fredericksburg area, but not like the surge in demand worldwide.

"The return on your investment only increases the longer you own it," he said.

But McAvoy and Hall agree that looking state by state, those that supply greater incentives to use the technology are where you'll find the greatest use.

Maryland, for example, is seeing a greater demand for solar systems than Virginia because it offers a healthy state tax break. Hall added that if this home were being built in Spotsylvania rather than King George, it would qualify for the tax break that Spotsylvania offers owners of qualified homes.

Hall also notes that viable energy-storage technology for residential use remains a work in prog-ress.

GEOTHERMAL SYSTEM

A geothermal heating and cooling system by Water Furnace will require little power to run. Also qualifying for a 30 percent tax credit, the unit works by circulating a mix of ethylene glycol and water through hundreds of feet of piping 5 feet underground near the house.

Because the underground temperature holds steady at around 55 degrees year around, a geothermal heat pump can easily use the circulating liquid to provide both heating and air conditioning.

A standard water-heater tank will be used to store heated water, but instant hot water for household needs will be provided by a tank-less water heater that is considered 98 percent energy-efficient, Hall said.

Because the house is so tightly built, an ERV, or energy-recovering ventilator, is used to draw in and filter fresh air that is circulated throughout the house.

CREATING AN ENVELOPE

The house is built from the ground up to keep warmed and cooled air in, and to prevent the intrusion of summer heat and winter cold from the the outside.

The footings and foundation of the house are layered in insulating Styrofoam to prevent thermal transfer from the ground. The exterior walls are two-by-six framing to allow for thicker insulation. The larger framing timbers also allow for 24-inch-on-center framing rather than 16-inch, which, Hall explains, puts more insulation and less wood--a poor insulator--between the walls.

Together, the SIS, or structural insulated sheathing, at R-5.5, and the wall insulation, at R-21, total R-26.5 (code is R-15). The ceiling will be R-50 (code is R-38).

With these techniques, the thermal envelope is created. The final steps involve sealing spots that might otherwise be ignored. The area where the basement bathtub drain enters the foundation is insulated. Mastic is applied to the duct joints.

Insulated boxes surround the CFL-dedicated recessed lighting cans. The recessed light cans require plug-in bulbs to prevent the homeowner from switching them out with screw-in incandescents, which would lower the home's overall energy-use score.

Hall said a blower test will be conducted before the drywall goes on because it's easier to detect the source of leaks that way.

Finally, the entire project is subject to third-party verification to achieve certified status.

Hall is inviting anyone interested to visit his open house this weekend to see the construction techniques without drywall.

Richard Amrhine: 540/374-5406
Email: ramrhine@freelancestar.com