Attic Fans

[disneychrista]

Do you have an attic fan? Does it help keep your house cool? Does it cost a lot to run? If you had one installed after living in your home, did you see a difference in your electric bill? What are the pros and cons?

 

[cvjw]

We had one in our last 2 houses. Had to stop using the last one due to pollen and allergens coming in the windows. Also the air conditioner didn’t run enough to keep the basement from getting mold when we used the attic fan too much. We much prefer to just use our air conditioners.

It has been years since we used the attic fan, but I don’t remember our electricity bill being any higher. Although we have very low electricity prices here - usually about $100 per month.

 

[NotUrsula]

I love the attic fan, but with the climate here it's really only useable in fall and spring (though I have cranked it up to freshen the house on the occasional freak warm winter afternoon.) One thing to be clear on; attic fans don't work properly in homes that don't have windows placed for cross-ventilation; there need to be enough open windows in every room to pull in air without creating something of a vacuum.

Our fan is quite loud if you're upstairs near it, but I think that newer models are much quieter. (Ours dates from the early 1970s, I think.)

 

[kanerf]

I have a window fan up in my attic. My attic is unusual in that it is finished. There are windows on both sides and it runs the length of the house. There are drawers built into the walls and other under eave storage as well. I have the window fan in the one of the windows and it is plugged into a smart socket so that I can control when it gets turned on and off.

 

[2Lunds]

100% thought this was going to be a thread about Constance's attic scenes on Haunted Mansion

 

[Dan Murphy]

We have both an attic fan and a whole house fan. The attic fan located on the roof vacates hot air from the attic, helping a bit to keep lower levels cooler. It also has a humidistat to turn on if the attic area is too humid but not hot enough, 105 degrees, to activate the fan. Humidity level is set to 60%. Both operations are automatic, if too high, turns on, low enough, turns of.

The whole house fan is located in the ceiling outside the bedroom area on the top floor of the house. If it is in the 70's, or maybe even the low 80's, AND it is not humid, we can open the windows, turn on the fan and have a nice, cool breeze in the house. Windows do have to be open and it can not be run at night due to the very high potential fire hazard if a fire were to start in the house while sleeping.

I think it would be difficult to actually measure dollar savings what with the very variable weather month to month, year to year. I'm confident that any savings are minimal.

I know of no cons to either the attic fan or the whole house fan.

 

[longboard55]

We have the whole house fan. Ours is a big one, they sell smaller ones now. Works great if it is cool at night, won't help in the day. Brings in cool air, cools off the attic and provides air movement.

 

[_19disnA]

Never had an attic fan. When we had our roof redone at a prior house several years ago, they added static vents along the roof since apparently the standards for such things have changed over the years. If you are thinking of adding a fan in the attic of your current house, I would make sure to talk with an HVAC company to see what they recommend and what impact such a fan would have on overall air flow. Whether it accomplishes what you expect would probably be determined by how your house is configured. If an older home lacking insulation, you are probably better off adding insulation. Attic tends to be warmer since heat rises and is also absorbed from the sun shining on the roof. Part of reason for attic insulation is to reduce heat transfer (both heat in summer and cold in the winter) to the rest of the house. Adding insulation can bring a year round benefit where an attic fan would probably only be of benefit in the summer.

I know some people who set their HVAC system such that the fan is always running even when the compression is not since they like the air movement. That seems to be more a matter of personal preference vs. saving money on cooling costs.

 

[ronandannette]

Here in this climate, attic ventilation is used for a different purpose. It’s important in the winter to duct attic air out to prevent condensation build up which then freezes, melts and if left unchecked, can run down and cause moisture damage on the interior. Lots of houses have active fans for this.

 

[LoveDaisy]

My parents have one. It works extremely well as long as it cools off at night. They are in New England and use it in the spring and fall and if we happen to get a cool summer night

 

[Dan Murphy]

Whole house fans compared to attic fans.

https://airscapefans.com/blogs/airscaping-101/airscape-vs-attic-fans

 

[gmi3804]

Roof vent fans are very helpful in keeping hot air out of attics during the summer.

 

[Disneefun]

We had one that we installed after we'd been here about six years. It didn't drive the electric bill up that much, mostly because it helped keep the AC use down a bit. In the end, it may really have been a wash. (Our house is relatively small, so our bills aren't extraordinary to begin with.) It had a thermostat, so it only ran when over a certain temp., not constant. I won't say it helped keep the house "cool," but I think it did help the AC not to run so much. (In other words, the fan itself did nothing to cool the house, but it did take a bit of the load off the AC.) While I'm not sure it did too much to lower the bills, I do think it may have helped extend the life of the AC unit.

Several years ago, we had to replace the roof and they put in vents along the ridge line. That has done far more to lower our bills and take the load off the AC than the fan ever did. It's been a noticeable difference, whereas the fan was like, "Eh, I think we're staving off the price increases, anyway."

My advice would be that if you're near the time of having to replace the roof, do that and have them install the ridge vents rather than buying a fan. If you're not near that time, then the fan might be a good option. I'm sure the newer ones are more efficient than the one we had. It can't hurt and it may help a little. But the roof change made a noticeable difference. (We also got thicker shingles than the old ones, and a better underlayment, that provide more savings, as well, so it's not all down to the vents, but they are a huge help.)

 

[SandyinMonterey]

We don't use our attic fan much. I think it's because we forget about it most of the time. It's very loud. The times we have used it, I did not see a jump in our bill and I don't think it cooled the house any more than beyond our AC. I do have a 3 level home so maybe that's why?

 

[disneychrista]

We had one that we installed after we'd been here about six years. It didn't drive the electric bill up that much, mostly because it helped keep the AC use down a bit. In the end, it may really have been a wash. (Our house is relatively small, so our bills aren't extraordinary to begin with.) It had a thermostat, so it only ran when over a certain temp., not constant. I won't say it helped keep the house "cool," but I think it did help the AC not to run so much. (In other words, the fan itself did nothing to cool the house, but it did take a bit of the load off the AC.) While I'm not sure it did too much to lower the bills, I do think it may have helped extend the life of the AC unit.

Several years ago, we had to replace the roof and they put in vents along the ridge line. That has done far more to lower our bills and take the load off the AC than the fan ever did. It's been a noticeable difference, whereas the fan was like, "Eh, I think we're staving off the price increases, anyway."

My advice would be that if you're near the time of having to replace the roof, do that and have them install the ridge vents rather than buying a fan. If you're not near that time, then the fan might be a good option. I'm sure the newer ones are more efficient than the one we had. It can't hurt and it may help a little. But the roof change made a noticeable difference. (We also got thicker shingles than the old ones, and a better underlayment, that provide more savings, as well, so it's not all down to the vents, but they are a huge help.)

Thank you this was a very helpful analysis. My parents got an attic fan when they remodeled and I remember my mom saying that it didn't really "help" and that her PGE bill was the same or maybe even a tad higher. I think I am about 10 years from a new roof (hopefully). I will keep the roof vents in mind when the time comes.

I am currently having my entire house rewired and the electricians mentioned it because the attic was 130 degrees at the time. They mentioned an attic fan so I thought I would look into it.

 

[Cogswel_Cogs]

I use it in mornings, to pull in cold air from outside, and at night pull all the cold air from downstairs. Do not use it for long periods of time. Also will use if something gets burned in cooking process