As we Californians endure our annual summer hot spells, let me give you the most cost-effective strategy for keeping cool (and saving A/C costs). It works especially well if you live within a dozen miles of the coast (as many Californians do!).
Install a “whole house fan” in your ceiling such as the model below (this one from Amazon for $300). It pulls air out of your house and into the attic, cooling both areas. Don’t forget to open windows before turning on the fan! It needs to be a bit cooler outside the house than inside for it to be effective, though the fresh air alone is often a welcome change.
It’s mostly used to cool down the house at the end of the day, and perhaps (as I do), to KEEP cooling it down with nighttime air, closing it up in the AM just as it starts getting warm outside. At the very least, is delays the need for A/C operating until later in the day. Obviously if it’s still hot outside at night, this doesn’t work well.
When the fan is not working, the fan opening into the attic from the house is AUTOMATICALLY covered by louvers that close when the fan turns off.
Bigger is better. Our fan is 36″ for a 2,500 sq ft 2 story home. Because of joists, 30″ or smaller fans cost less and are much easier to install (no cutting of joists), but of course move less air per minute.
You will need a peaked roof (as opposed to flat) and an attic — the attic (even a low attic) is the place the fan pushes the air from the house. If you put in a fan over 30″ in size, probably you will want a couple of passive wind turbines (not to cool the house much, but rather as EXHAUST ports for the air being blown into the attic), or at least gable vents.
Professional installation can easily cost much more than the fan — the mounting, the wired controller, the wind turbines, etc. If YOU are handy, it can be done for less than $500 with the fan included. Indeed, the vender of this fan example (below) claims they can provide the fan installation for less than $200.
What you get is a cooler house, including a cooler attic. We cut our A/C use 70%-80%. It can be more if you’re not a wuss like me. Fresh air and a breeze is usually welcome by all. Probably cuts down a bit on mold and helps reduce deterioration in the attic, but I’m just speculating about that (California air is dry).
It’s a cheap alternative to solar, and per buck saves a lot more dollars — plus your life will be more pleasant. Depending on current law, you might get a modest energy tax credit for your efforts. Also your local utility may offer a rebate for such an installation ($100 or so, varies).
The fans usually come with louvers, which automatically open and close to accommodate the fan’s activity. Keeps the alligators out.
BTW, get a 2-speed fan with a timer (most meet that requirement, but you need your controller to handle that). When it’s warm weather, we often leave our whole house fan on late into the evening — even all night — to really cool down the house with the fan on low (quieter). We turn off the fan and button up the house about 8 AM or so. We don’t need no stinkin’ A/C until 2 PM — if at all). About 5 PM (depending on outside temperature), open up your house and put the fan on “high.” You’ll be delighted with the improvement.
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https://www.amazon.com/Cool-Attic-CX30BD2SPD-2-Speed-Shutter/dp/B00562CSL6