Solar-heated hangars

StoryImage( ‘/Images/Story//Auto-img-117269399113653.jpg’, ‘Photo by Sonia Vogl’, ‘Bob Moreland with solar heating system. Flexible red plastic pipes carry heated water under the floor of the building. At Rockford Airport, January 2007.‘);

Bob Moreland learned to fly as a bush pilot in Alaska and later became a pilot for American Airlines. Now retired from commercial flying, his love of small planes and the camaraderie of other pilots is met by his recently-built energy-efficient hangars at the Rockford airport.

In constructing the hangars, Moreland set out to solve two interrelated problems. One is that most of the wear on a small plane’s engine occurs when starting it cold. Oil takes 20 to 30 seconds to warm up and thin sufficiently to flow inside the engine block, limiting erosion of the cylinder walls.

The second is that when a hangar and plane are cold, and moisture-laden warm air replaces the cold air, some moisture condenses onto cold plane surfaces. Within the engine itself, a small amount of rust forms on cylinder walls. When the engine is started, that thin coating of rust is wiped off. Eventually, the gap between the piston and the cylinder wall is sufficient so the engine begins to use oil, loses compression and has to be rebuilt.

Some insulation was put into older hangars and an industrial gas burner was hung on a wall. Keeping the building heated was expensive, so it was common practice to turn on the furnace a few hours before a flight to warm up the plane before starting it to reduce engine wear.

After building hangars using a more efficient gas boiler to heat water and run it through plastic pipes under the cement floor, Moreland wondered about generating some of the building’s heat with solar hot water panels. After a phone discussion with us, he decided to contact an installer to further explore the solar option.

He was determined to make the buildings more energy efficient and use solar hot water heating. He had two pole buildings erected on the property, which is leased from the Rockford Airport. The 32,000 square feet of buildings houses 22 airplanes.

Wall thickness approaches 12 inches. Steel covers the outsides of the walls. Insulation blown into them provide R 40 ratings. For comparison, a home built in the 1960s is likely to have an R 11 wall.

Eighteen inches of insulation was installed in the ceiling providing an R 60 rating. A 1960s home may have R 19 ceiling insulation. Insulation levels in the new 1-watt home include R 60 in the ceiling, R 40 in the walls and R 20 for the foundation. Such homes use one-tenth the energy of a 1960s home of a similar size.

A continuous loop of plastic pipes laid on nearly a foot of sand carries the heated water under 4 inches concrete floors. One of the buildings has 2 inches of foam insulation under the pipes. Although physics principles suggest the floor without insulation will lose some heat to the ground during the winter, Moreland has yet to establish if the insulation has influenced building heating loads.

One building has 10 solar hot water panels; the second has 14. The performance of the building with 14 solar panels was not as effective as anticipated, as the panels were set to maximize year round rather than winter performance. Panel angles will be changed to increase solar heat gain during the winter.

To prevent the fluid in them from freezing, water drains out of the panels when their temperature falls below a set point. The fluids also drain down when the room temperature approaches 80 degrees Farenheit to prevent the building’s becoming too warm for comfort. Under full summer sun, the temperature in the panels can reach 140 degrees Farenheit .

For supplemental heat during the night or on cloudy days, an efficient gas water heating unit automatically turns on when the water temperature in the system drops. During December, Moreland’s gas bill was $27 for 32,000 square feet of space, about one-tenth that of adjacent hangars heated only by natural gas.

Moreland is very pleased with the performance of the buildings, which he proudly claims uses less supplemental fuel than was predicted by an engineering firm’s estimates done prior to the building’s construction.

He wonders why every warehouse in a cold climate does not use a combination of high insulation levels and solar hot water heating like his. He also plans to build a home using industrial materials and construction approaches used in his plane hangars. With low energy bills and construction costs of roughly $60 per square foot, it is understandable why he is thinking about applying this approach to home construction.

Drs. Robert and Sonia Vogl are founders and officers of the Illinois Renewable Energy Association and coordinate the annual Renewable Energy and Sustainable Lifestyle Fair. They have 3.2 kW of PV and a 1 kW wind generator at their home. Forty acres of their 180-acre home farm are in ecological restorations. They are also active in preserving natural areas. They are retired professors from Northern Illinois University.

From the Feb. 28-March 6, 2007, issue

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