In "Solar Heated Pig House," Jim Murphy told how he and John Feyen turned half of the roof of their Wisconsin pig farrowing barn into a solar collector. Now thanks to a $5,000 grant from the Department of Energy, the second half of the roof collector is finished. Instead of the hot air being blown into the barn, the "free" solar heat is ducted into pipes set into the structure's concrete floor.
"When the warm air was pulled directly into the farrowing house," reports John, "the temperatures inside the barn would often reach the high 70's during the day, but sometimes dropped to the upper 40's at night. Now we can maintain a nearly uniform 60 degrees all the time. Of course, a consistent temperature isn't particularly important for animals, but would be necessary in a building for human occupants."
Unfortunately; just before the second half of the collector was completed (the wooden batten strips had not yet been secured over the seams where the fiberglass-reinforced clear resin sheets overlapped), a terrible windstorm ripped the covering right off. That could have been a serious setback, but winter was just about over and the farm's regular insurance coverage paid for the loss.
"The claims adjuster told us that our collector wasn't 'standard construction,' and came out to make sure the problem wouldn't recur," John told us. "Had it been a unit that was just hung on somehow, the agency might have felt differently. Since our solar 'system' was an integral part of the barn, we were able to collect on the damage. I was really sorry that the accident happened, because I didn't want to see the insurance company face a claim on the first sun-heated building they'd ever covered. But let's face it: Solar energy is a reality!"
And sun power is being put to work in a number of ways around the Murphy/Feyen farm. A solar grain-drying system will be ready to go into operation next fall, while a solar-heated machine shed—which also has its warm air ducted into the floor—will be complete by the time you read this. The Feyen house is also being redesigned to incorporate heat from the sun, but that project won't even get underway for almost a year.
In the meantime, the DOE is collecting data on the ratio between the amount of solar energy available to the barn's collector and the number of Btu's the system actually produces.
"So far," Feyen notes, "we're running at about 60% efficiency. Commercial collectors can sometimes get up to 80% and more, but then, such units cost 10 times as much as ours did. The DOE also wants to know about cost-effectiveness: how long it will take the system to pay for itself. As far as we're concerned, the rooftop 'furnace' paid its way in two seasons, but we've given the Energy Department officials a conservative four-year estimate.
"The fact is, it's hard for folks to believe just how well our inexpensive, easy-to-build unit does work!"