Thursday, July 24, 2008

Solar-Powered Attic Fans

Is it like a sauna in your attic?

I once stored some holiday candles in the attic. Big mistake. Instead of beautiful tapers to adorn my table, I had flat, amoeba shaped candles.

If you own a home … or if you have a receptive landlord, here’s a tip that can reduce the heat: Install an attic fan … not just any attic fan, a solar-powered attic fan. By reducing attic temperatures, attic fans can help reduce summertime cooling loads while at the same time providing ventilation.

Solar powered fans rely on a small (10- or 20-watt) solar panel to power a DC motor when the sun is shining. The fans, which exhaust air at a rate of 800 to 1200 cfm, are installed with intake vents (such as soffit and gable vents) to provide high-capacity powered ventilation without electric operating costs. Most vents are mounted high on the roof, near the ridge, and combine with soffit or gable vents for balanced intake and exhaust air streams. Ventilation is only provided when there is ample sunshine to power the fan motor. The brightest sun (and, therefore, fan speed) typically coincides with the time of greatest need. In other words … at the hottest time of the day.

Because solar-powered fans are fueled by the sun, there are no operating costs. That makes them more affordable to use than conventional attic fans. Although equipment costs are greater than conventional attic fans (about $200 more), the cost to bring electrical wiring to the attic to supply a conventional ventilator closes the gap on installed cost.

Solar fans eliminate potential problems: If there is inadequate attic intake air and poor sealing between the conditioned space of the home and the attic, powered attic fans can potentially draw air from the house into the attic. Not only can this compromise energy efficiency, it can increase the risk of attic moisture problems as well as increase the risk of drawing the byproducts of combustion into the house (a process called backdrafting). These problems are eliminated with a solar-powered fan.

With an attic fan, melting candles will be a thing of the past.

As always, I would love to hear your ideas for reducing, reusing and recycling. Just click on the comments link, located at the bottom of each post, and let me know what you think and how you conserve.