Solar and geothermal systems are making many an American household more energy efficient, but until now, wind turbines have been largely excluded from the residential green building equation because of noise and space issues. Now, the makers of a quieter, space-saving home wind turbine are hoping to change that.
Last week, the Grand Rapids, Mich.-based manufacturer Cascade Engineering announced domestic production of a small, patented wind system that has already been installed in 250 sites in the U.K. Whereas small wind turbines typically are designed with three open blades, the Swift wind turbine is made up of five blades surrounded by an outer "diffuser" ring that cuts noise levels to 35 decibels, according to company officials.
Noise mitigation notwithstanding, the diffuser ring's other significant advantage is that it reduces ancillary vibration. As a result, the Swift can be structure-mounted directly on the roof or side of a home in lieu of a freestanding pole or tower--making it a more viable green feature in urban or suburban settings with tight space and height restrictions. "There are more than 15 million homes and one million small businesses in the U.S. that could easily put this on their buildings," says Jessica Lehti, senior sales and marketing manager for Cascade.
Designed and prototyped by the Scotland-based company Renewable Devices, the Swift can generate an estimated 2,000 kilowatt hours in a year (a figure based on average wind speeds of 14 miles per hour), offsetting roughly 20% of the average home's annual electrical usage.
The device, which resembles a large weather vane (click here to see a video), measures seven feet in diameter and requires a 2-foot roofline clearance. Installation by a certified installer takes four to six hours with a total cost of $10,000 to $12,000. The product can be used in new construction projects as well as retrofits, and is estimated to pay for itself in three to four years (with a 5-year warranty and 20-year life expectancy).
So far, Cascade has installed nine units in the U.S. and has an order backlog of about 50 more devices, Lehti says. The company expects sales to pick up come January when homeowners feeding power back into the grid will become eligible for a $1,000 federal renewable energy tax credit. Businesses using the devices on their commercial buildings will be eligible for a $4,000 tax credit.
About those tax credits: for more information about federal and state incentives for renewable energy systems, check out the DSIRE database, an ongoing project of the North Carolina Solar Center and the Interstate Renewable Energy Council (IREC) funded by the U.S. Department of Energy.
Jenny Sullivan is senior editor, design, for BUILDER.