Can Attic Followers Cut back Air Conditioning Payments? – Inexperienced Properties
I’ve seen conflicting information about attic fans. Some sources say they will reduce the cost of air conditioning by lowering the air temperature in the attic. Others say they will draw conditioned air into the attic and increase energy usage. Are roof fans effective in reducing air conditioning costs?
In general, roof fans are not effective at reducing air conditioning costs. The benefit of lowering the temperatures in the attic (and therefore the reduction in heat gain from the attic to the house) is usually offset by the power consumption of the fan and the increase in air leakage from the house to the attic that can result from the attic pressure drop Attic fan. As a rule, it is better to use the money you would spend on an attic fan to increase the level of insulation in the attic and the airtightness of the attic level.
Now a fan is a different animal all over the house, and these can make sense in certain climates if used properly. This is a large volume fan (sometimes installed in a ceiling opening that extends into the attic) that is used in place of mechanical air conditioning at night. This cooling strategy only works in climates in which the temperature fluctuates considerably between day and night, the night temperature falls below 65 degrees and the humidity outside is not too high. This is how it works: During the day, the house is kept fairly closed with closed windows and blinds in unused rooms in order to minimize unwanted heat gains. At night the windows are opened and the whole house fan is operated. The fan sucks air out of the house, and cool outside air is drawn in and replaces it. The energy required to operate the fan is much less than the energy required to operate the compression air conditioning system.
– Alex Wilson, founder of Environmental Building News, editor of the GreenSpec Directory of environmentally friendly construction products, publisher of BuildingGreen.com and GreenBuildingAdvisor.com