OCR Text |
Show Earth tubes use old-fashioned old-fashioned ingenuity Earth tubes are not a rock group or burrowing bur-rowing animals. But they are space-age inventions which use a timeless phenomenon phenome-non to heat and cool everything from people peo-ple to pigs. An amazingly simple concept, the earth tube takes advantage of what rabbits have known for years. The ground even just a few feet below the surface remains a fairly steady temperature all year round, says Daniel J. Meyer, Penn State assistant professor pro-fessor of agricultural engineering. "You can use that to heat or cool a building with just a fairly short distance of pipe and a fan," says Meyer. By laying a horizontal tunnel a few feet underground away from the building to above-ground oudets several hundred feet away, air coming into the building will be a little closer to an optimum temperature. "If it's 90 degrees out, the air coming in can get as low as 75 or, in winter weather, the air can get into the low 40s. It'll average aver-age 50 in the fall and spring, " Meyer says. For most of Pennsylvania, the ground temperature maintains an annual mean of 47 to 52 degrees and the southeastern corner cor-ner climbs a little higher, says Meyer. Across the country, those means ranee from 77 in Florida to 40 in the far northern reaches. - - '. Designed in the late 1970s as a home heating and cooling aid, the earth tube heat exchanger concept has had a moderate success. : y Five years ago, Meyer buried an 80-foot 80-foot line from his house. In the winter, it heats the air coming into his wood stove, and in the summer acts as an air conditioner. condi-tioner. "I also run a trickle of water through it for evaporative cooling," he says. In 1981, the idea was suggested as a means to reduce fuel costs in veal calf and swine houses, Meyer says. But the idea hasn't yet swept through die farming community. com-munity. "There may be 100 units in the country," coun-try," with perhaps 10 of those in Pennsylvania. Pennsyl-vania. "Midwestern farmers are using it more," he says. Two of the first farmers in Pennsylvania to use it were Ken and Wally Whippo, of Enon Valley, who installed the system when they built their new swine farrowing house and nursery in 1981. "In the coldest weather, the lowest our temperatures have ever gotten are 40 to 42 degrees," Ken Whippo says. The geothermally heated air comes into the building in a service alley, where it is then drawn into three livestock rooms. Two of the rooms are nurseries, which hold 120 pigs each. For more details about earth tempering systems, write to Dr. Meyer at 204 Ag Engineering $uilding, The Pennsylvania State University, University Park, PA 16802 and ask for publication PIH-102. |