In Southern California we are currently experiencing a heat wave, which is typical for the month of August. Our daytime temperatures are reaching 90 to 100 degrees and the temperatures during the late evening and early night are not much cooler thanks to the high pressure system. At about 9:00 PM the outside temperature was 84 degrees, definitely not a good time to use a whole house fan. This was one of the nights I was grateful for air conditioning.
In the morning, however, at about 6:00 AM the outside temperature was 68 degrees. Although some may think, “why would I use my whole house fan when my home is already cool from running the air conditioner”, the reason is quite simple. Even though the temperature inside the home may be cool, the temperature in the attic and walls are not. They retained the heat from the day before and the temperatures in those spaces could be well above 100 degrees. As a result, unless that heat is removed it will radiate into the home, quickly heating up the living space. It’s for this reason that I want to run my whole house fan.
At 6:00 in the morning I turned on the whole house fan and ran it for about an hour, making sure that the temperature outside never exceeded the indoor temperature. I then turned off the whole house fan and closed the windows. My entire home (living space, walls and attic) where now cool and comfortable, delaying the need for air conditioning.
While I heard some of my neighbors air conditioners turn on as early as 9:00 this morning, I knew I wouldn’t have to run mine until much later, significantly saving on my cooling bills!
Although a whole house fan is not designed to eliminate the need for air conditioning, it can help reduce the need for it, even during a heat wave.