Home is power source

When is a test score of 21 on a scale of 100 something to be proud of? When it reflects a Home Energy Rating System score, and the lower the score, the better.

When we last visited King George County to see this J. Hall Home last fall, it was a work in progress.

With the drywall yet to be installed, it was a good time to get an idea of what area builder Jeff Hall was trying to do: build the region's first certified "net-zero" home, which means the house will generate as much energy as it uses.

Today the home is completed, and new owners David and Jalna Rasmussen have moved in, although this winter's snowfall stalled the final grading of the lot. But that's not a top priority anyway. What's important is that the house is being lived in, is generating its own power and is responsible for a carbon footprint so tiny that the planet hardly knows it's there.

"Just about everyone who wants a house built today is interested in conserving energy," said Hall. "It's not necessarily the granite countertops or whatever, it's the attention to detail, to what you can't see that means saving energy and money."

Every aspect of the house is in some way tied to how it makes, uses and saves energy. Located just off Caledon Road, the house was situated at the exact angle--facing south--and the roof pitch given the ideal slope to allow its photovoltaic solar panels to operate as efficiently as possible.

The German-made Schuco panels, distributed by Mid-South Building Supply, generate 3.6-kilowatts of power, which most of the time is enough to run the house. On sunny days, they will generate surplus power that is returned to the power company through an energy inverter, thereby reducing the Rasmussens' power bills to a minimum.

For the owners, the benefits (economical comfort) and the fringe benefits (being "green") are wrapped up in a package that will serve them well in the short and long term.

"We gave Jeff [Hall] pretty much free rein," said David Rasmussen. "We told him we wanted to heat the house with a candle, and we ended up with an EarthCraft Tier 3 home."

Tier 3, or Platinum, is the highest possible level under the EarthCraft certification program.

Rasmussen said that building a house in which the couple could age comfortably had both economic and physical aspects.

"As long as we are a petroleum-based society, energy is never going to get any cheaper, so we wanted to do what we could to make it cheaper," he said.

The house has a 1,500-square-foot main level and a basement that doubles the living space. Rasmussen said that universal design was the other part of the aging-in-place equation, so the house has 36-inch interior doors throughout, and hardwood floors that provide flat thresholds into bathrooms.

Though the couple moved in just a few weeks ago, Rasmussen is already impressed with how comfortable and draft-free the house is--not to mention that he can leave the thermostat 2 degrees lower than in their previous home and stay plenty warm.

During a tour of the property on a sunny day earlier this week, the electric meter was moving backward, showing that power from the house was going back into the grid, and representing dollars the Rasmussens won't have to pay for electricity.

Providing comfort is the responsibility of the Water Furnace geothermal heat pump heating and cooling system.

The unit works by circulating a mix of ethylene glycol (antifreeze) and water through 320 feet of tubing that's buried 5 feet underground. There, the temperature remains a fairly constant 55 degrees, unlike the seasonal air temperature, so the heat pump doesn't have to work so hard. In the summer, the liquid leaves the house warm, the heat is transferred into the ground and the liquid comes back cool. In the winter the process is reversed.

The home's tight construction allowed for use of a less expensive 2-ton system, rather than the 3-ton originally planned.

Hall said the system also provides heated water that's stored in an insulated tank. It works with a tankless water heater that supplies hot water on demand, heating it further only when necessary.

This conventional frame house was built from the basement up to form an envelope that blocks out hot and cold air.

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, results in more insulation and less wood--a poor insulator--between the inner and outer 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).

Much recessed lighting is used, and insulated boxes surround CFL-dedicated cans. The cans require plug-in bulbs to prevent the homeowner from switching them out with screw-in incandescent bulbs.

The sun not only generates energy though the solar panels, it contributes to the home's efficiency passively as well. Window and wraparound porch overhangs are designed to shade the home when the sun is high in the sky during the summer, while letting the sun's warmth reach the walls and windows in winter.

Even the amount of space that was cleared around the house was determined by how much of a shadow the remaining trees would cast on the house.

Three "sun tubes" are used to provide natural light to windowless interior rooms.

In round numbers, Hall said, such a house built to code (not including the lot) would cost about $250,000. The energy-saving features add between 15 percent and 20 percent, bring the final cost to about $300,000.

The next advance, he said, will be a cost-effective battery system that would store a home's surplus energy. That will allow future homes to go off the grid entirely.

Dan Dukes of Green Source Raters consults with area builders looking to build homes that achieve high energy efficiency. His guidance will help a home achieve the best Home Energy Rating System score it can, given the level of investment in energy-conserving features and materials.

The home that J. Hall Homes built for the Rasmussens achieved the best score, 21, that he is aware of in Virginia. EnergyStar certification, and eligibility for Spotsylvania County's tax break, is 85.

Some facts:

This house has a full exchange of air every 17 hours and uses an energy recovery ventilator to regulate fresh air intake. The typical code house exchanges air about every two hours--a lot of new air to keep cooling or heating.

Duct leakage is a negligible 0.83 percent. EnergyStar standard is 6 percent; conventional construction historically is about 20 percent.

Annual heating cost is projected at $98 per year; cooling, $86 per year. The real-life numbers may be a bit higher. "Service charges for gas and electric for this home are $199 [annually]," said Dukes. "The homeowners of this house are going to pay almost as much in service charges as they are for energy."

The house saves 22 tons of CO2 compared with the same house built to code. That is the equivalent of not burning 2,278 gallons of gasoline.

--Richard Amrhine

Home is power source

March 12, 2010 4:52 am