Staying cool during the summer months is a major priority. In some places the heat may be misery-inducing, while in others it can be downright dangerous. At my own home near Phoenix, Arizona, the thermometer read a high of 115°F this week. This got me thinking about my family's dependence on air conditioning, and by extension the functionality of the power grid. The YouTube channel 50 Acres & a Cabin recently posted a video that's relevant to this topic — it shows one way to build a DIY whole-house fan as an “off-grid alternative to air conditioning.”
The concept of a whole-house fan is not a new one. Hot air rises, and the enclosed space of a building serves as a trap for that hot air to build up. By placing a high-flow fan near the top of the house, the hot air can be sucked out and replaced by cooler air drawn in through ground-floor windows. In the video below, 50 Acres & a Cabin encloses, mounts, and wires a powerful fan into the loft of his off-grid home.
However, this cabin runs on a 24-volt DC electrical system. It has some advantages, but also makes plug-and-play fan options more limited than they would be on a standard 12-volt system. So, the builder got creative and selected a 24-volt truck radiator fan — it's designed to pull large amounts of air through a radiator to prevent a vehicle from overheating, so it provides more than enough flow for this application. The downside is that it's extremely loud. The builder commented that he plans to wire in a controller to allow the fan to run at lower speeds, and this sounds like a good idea to us.
While I won't be taking a sawzall to my attic and slapping on a radiator fan, this video got me thinking about installing a whole-house fan as a backup (or supplement to) my home's existing A/C system, ideally in conjunction with solar panels and a battery bank.