Save Home Energy: Improve Your Home’s Ventilation
The idea of letting hot summer air into your home to help keep it cool sounds paradoxical. But some parts of your house need to be well ventilated both summer and winter, regardless of the temperature outdoors. In temperate weather, a whole-house fan that pulls cool, outside air through the entire house can substantially reduce the money you spend on air conditioning.
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Ceiling fans circulating air within a room also help cut cooling bills. They do so by gently drawing cool air up from the floor, where it tends to collect on hot days. Reversed in winter, a ceiling fan circulates warm air that accumulates near the ceiling.
Helping Your House Breathe
When the weather sizzles, ventilation keeps attic spaces from overheating and radiating heat into living spaces below (see illustration above right).
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The heat flowing from the attic causes your air conditioner to work harder a greater expense to you. Even attic floors that are well insulated can’t withstand the onslaught of all this heat. What will help is a series of vents that allow the warm air normally trapped inside to flow up and out of the roof, to be replaced by cooler air brought into the attic by way of the eaves. Results can be dramatic. Ventilating an attic can easily lower the temperature from 150 to 115 degrees F.
In winter (see illustrationabove left), ventilation clears the attic of warm, moist air that may seep upward from living spaces below. Allowed to remain in the cooler attic, this humid air would deposit its moisture as condensation, not only on joists and rafters, but also in attic insulation, reducing its effectiveness.
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Cold air directly below the roof also helps avert ice dams–the buildup of ice along eaves that can cause roof leaks. Keeping the roof at a uniformly cold temperature prevents snow on the upper, often warmer parts of a roof from melting, then refreezing at the eaves.
During summer months, a whole-house fan can draw in cool air through open doors and windows and exhaust it through the attic (see illustration at left). Be sure to turn off the fan when you close the windows and doors. If you don’t, the fan motor, straining to pull air through closed windows, will quickly burn out.
Source:http://www.hometips.com/articles/sunset_books/saving_energy/save_energy064A.html