UNH solar project is a lot of hot air -- in a good wayJun 30 - McClatchy-Tribune Regional News - David Brooks The Telegraph, Nashua, N.H.In an example of the simplest type of solar energy being put into large-scale practice, 2,400 square feet of a south-facing wall on Kingsbury Hall on the UNH Durham campus has been turned into a passive hot air system for the College of Engineering. The project, partly paid by a $59,750 grant from the New Hampshire Public Utilities Commission, covered the south-facing wall of the rooftop mechanical systems extension with a black, perforated panels over a metal grid. Sunlight heats the air trapped between the panels and the brick wall, and the air is fed into the building's ventilation system during cooling season, which makes it much cheaper to heat the building. In warm weather, the hot air ventilates back into the atmosphere through perforations in the glazed surface. Although solar ventilation preheating systems, as they are known, get less attention than solar electricity, it can be just as effective reducing energy usage by commercial buildings. Kingsbury Hall is home to the College of Engineering and Physical Sciences, so it's full of labs as well as classrooms and offices. "Ventilation heating and cooling has the largest impact and footprint of just about any process in commercial and industrial buildings," said Matt O'Keefe, UNH's energy manager. "Kingsbury Hall requires continuous ventilation to make up for the significant exhausting required to maintain a healthy indoor air environment for its laboratory spaces. " The glazed collector panels were installed by a Maine firm called Shift Energy, which has done similar work for commercial buildings with systems that look like the sides of metal industrial buildings. It touts a "perforated glazing technology" used at Kingsbury Hall because it is a better looking for use as cladding, or covering of outer walls. "Metal cladding systems, we do that as well, but once you get into a school or something that's architecturally rich, it becomes a handicap rather than a feature," said Mick Dunn, owner of Shift Energy, in a phone interview. Solar hot air systems may differ in technology from solar photovoltaics, which turns sunlight into electricity, and solar hot-water systems, which pre-heats water, but all three have the same goal: Taking the energy in outdoors sunlight and moving it indoors, so it can replace energy produced by fuel-using power plants. The National Renewable Energy Laboratory estimates that solar ventilation preheating converts approximately 75 percent of sunlight's energy into usable form, an extremely high figure, and calls it "among the least expensive of all renewable energy technologies to install," noting that they are "technically simple and require little maintenance." UNH estimates the solar air heating system will reduce ventilation heating costs for Kingsbury Hall by around 60 percent to 80 percent. As a passive system with few moving parts, solar air heating systems are relatively inexpensive, although installation labor involved in putting them atop existing walls and connecting them into existing ventilation systems can provide challenges. The real return on investment, Dunn said, comes when they're created as part of new construction, since some kind of cladding has to be put on every wall, anyway. "It's a similar or even the same cost, and you're essentially getting free energy out of it," Dunn said. Solar hot air systems aren't practical overall for residential homes because of difficulty integrating them with a home's heating system. Small "hot box" systems can be bought or built to help heat up single rooms; an attached greenhouse does the same thing. Dunn said the systems, marketed through commercial HVAC, or heating-ventilation-air condition, distribution channels, are becoming more common. "We've done about 20,000 square feet of them in New Hampshire -- this is a typical-sized project for us," he said. The company has done about five of them in New Hampshire, many more in Maine. http://www.nashuatelegraph.com/ http://www.energycentral.com/functional/news/news_detail.cfm?did=29152691 |