Attic view of gable vents where the fan will be mounted, facing south.

This is a home improvement project I’ve been thinking about for a long time that may offer considerable benefit. It’s been on my mind since our first summer in the house. Cooling our home in the summer to a comfortable level is somewhat challenging and expensive. Our home was originally built in the 1920s. As a result, it simply doesn’t have much insulation. Yes, some was added over the years, but it just isn’t sufficient for a home of our size.

Unfortunately, due to other factors related to when this home was constructed, we can’t simply drop more insulation everywhere in the attic. I’ve added some, but it simply cannot be done in most parts of the attic without some major renovation.

Recently, I ordered a Natural Light Energy Systems 30W Gable Mounted Solar Attic Fan. The intention is to cool down the attic considerably, thus also making it easier to cool the house.

Whether or not attic fans are effective appears to be an area of significant debate. Arguments on both sides of this issue seem to be valid but I’ve also noticed that many of these discussions ignore one important factor: not all home are constructed the same way.

If our house was of more modern construction, well insulated, and had lower ceilings, then I doubt we’d see a significant improvement. However, I strongly believe that our attic, and our high ceilings, serve as a heat sink that, unfortunately, radiates a considerable amount of heat down into our home. As the sun sets it actually seems to be more difficult to cool the house..

So what are the detractors claiming? Basically, by adding an attic fan one has created positive airflow that will suck cool air from the house and out through the attic. I have no doubt there is some truth to this, but again, not all homes are constructed the same way or have the same problems. I’m also skeptical that this attic fan would be able to draw that much air up through the ceiling or walls. We have a very large attic and it will take far less energy to simply draw outside air in through the gable vents.

There are a couple of reasons that I think this solar fan will actually be helpful. For one, we don’t have the kind of attic ventilation that more modern homes have. Our roof does not have ridge vents. We don’t have soffit vents.

We only have a handful of gable vents and on the occasions that I’ve been in the attic during the summer (for only a few minutes at a time) I didn’t notice any airflow.

Our attic is huge.

We’ve sometimes wondered if the house was engineered in a manner that would support adding an additional floor. I still don’t know the answer, but this is a significant space for heat to build up and sit. The heat will continue to radiate downward, into the rest of the house, well after the sun has set.

Obviously if I install this fan, and our bills actually increase, I’ll know this didn’t work. However, I think this is very unlikely. It’s quite possible that the fan may nearly pay for itself before the temperatures begin dipping back down in the fall.

Installation will be a challenge due to the heat in the attic. Early morning is the best time to access the attic, due to the length of time it takes to radiate the heat trapped there, so it’s quite possible I’ll have to temporarily mount the fan and panel in a way that will let it run to cool the attic just enough to be able to mount everything properly at another time (this includes blocking the gable vents that will be directly next to the fan itself).

Now, I certainly could have decided to go with a wired fan but there are two reasons that I didn’t. The first is that I simply don’t know how effective this will be. The second reason is that I’m trying to save money on electricity, not add to it, even if the addition is very low.

For safety reasons I’ve ordered a safety switch for the fan, which will kill the fan in the event of a fire (hopefully that will never be needed). I also ordered a thermostat. Sure, I want to cool the house in the summer but I don’t want to cool it in the winter. In colder temperatures a buildup of heat will be an advantage. The switch will shut off the fan automatically when the temperature dips below 70 degrees.

At some point I hope to have another blog post mentioning the installation and how effective we think it is.