Mar 15 2013
Sacramento Living: The Economics of a Whole House Fan
It’s Cool Outside…So Why Is My Air Conditioner Still Running?
The warm, California day has drawn to a close, the sun has gone down, and temperatures outside have dropped to a cool level… and yet your air conditioner continues to run throughout the night to keep your home cool. There must be something wrong with this picture, right? And yet for homeowners in areas like Sacramento, Fresno, and Bakersfield, it is an all too common experience during the warmer parts of the year. If this sounds familiar, a whole house fan could be the answer.
The Dutch-Oven Effect
It doesn’t seem to make sense that the outdoor temperature can be nice and cool, and yet your home continues to feel hot – even at night. But there is a simple explanation. During hot days the temperature in your home’s attic can reach well above outdoor temperatures. At the end of the day, when outdoor temperatures have dropped, our homes often don’t cool off on their own. Like the hot coals on top of a Dutch-oven lid, the attic is still cooking from all the heat exposure during the day. So even after the outdoor temperature has cooled down and become comfortable, the hot attic continues to radiate heat into your home. We call this the “Dutch-Oven Effect”.
Sacramento and Fresno homeowners have experienced this all too often – and it is happening earlier and earlier in the year. Today in Sacramento, the temperature reached 78 degrees. Just yesterday, March 14th, Fresno hit a new temperature record for the day – 85 degrees. Our southern California neighbors in Riverside hit a temperature of 95 degrees. 95 degrees in mid-March!
Whole House Fan to the Rescue!
A whole house fan works by drawing cool outdoor air inside through open windows and exhausting hot indoor air through the attic to the outside. Running a whole house fan whenever outdoor temperatures are lower than indoor temperatures – such as during the evening, night-time, and early morning – will cool a house and vent the attic of hot air at the same time. As daytime temperatures rise, the whole house fan can be turned off.
A whole house fan can be used as the sole means of cooling or to reduce the need for air conditioning. If both methods of cooling are present, seasonal use of the whole house fan (during spring and fall) may yield the optimum combination of comfort and cost.
Let’s Talk Dollars and Cents
Okay, so you’re probably wondering how much it costs compared to other cooling options, so here’s a breakdown according to the U.S. Department of Energy*:
- Operating a properly sized 2-ton air conditioner with a seasonal energy efficiency ratio (SEER) of 10 in Atlanta, Georgia, costs over $250 per cooling season (1,250 hours), based on 8.5¢/kWh, or roughly 20¢ per hour of runtime (NOTE: in most parts of California, the electric rates are actually much higher)
- A large 18,000 Btu/h window unit air conditioner with an energy efficiency ratio (EER) of 8.8 costs more than 17¢ to operate for one hour.
- By contrast, a whole house fan has a motor in the ¼ to ½ hp range, uses 120 to 600 watts, and costs around 1¢ to 5¢ per hour of use.
At Synergy Companies, we have procured some of the quietest and most energy efficient whole house fans on the market from QuietCool Manufacturing. If you are a Sacramento homeowner, you may even qualify for PACE financing through Clean Energy Sacramento. Or in western Riverside County, you may qualify HERO Financing, a PACE financing program available in that neck of the woods. Call us today and we’ll help you determine if a whole house fan is good solution for your home, and what financing options may be available to you.
* U.S. Department of Energy, Technology Fact Sheet, Whole House Fan