4 ms·

If you live in a house with poor airflow, consider a whole house fan. Run it in the evening / overnight / morning with the windows open, then shut the windows (

If you live in a house with poor airflow, consider a whole house fan. Run it in the evening / overnight / morning with the windows open, then shut the windows (and shades if you don't mind the darkness) during the day. There is an Ask This Old House episode where they install a whole house fan. [0] Even if this doesn't remove the need for AC, it will decrease the load on the system by increasing how much heat the home's interior has to absorb before the AC kicks on. We called these "attic" fans when we had one in the 1970s. They were huge, required a massive hole in the ceiling, and were loud. Modern ones are sound / thermally insulated, much smaller, require a smaller hole in the ceiling, etc. [0] https://www.youtube.com/watch?v=Rwe8c6wr0AA https://www.youtube.com/watch?v=Rwe8c6wr0AA

ethhics 5y ago
From my previous research on whole-house fans, they are a wonderful device to have so long as you live in a place where the nights are cool, and most importantly, low-humidity. Unfortunately where I live and it’s 80+% RH at night, a whole-house fan would just give me mold.
- handrous 5y ago
  Modern US houses, at least in much of the country, aren't built to be livable or to survive themselves without year-round temperature control. Partly, this is because optimizing for building survival and inhabitant comfort without AC and with only limited heating is at-odds with designing for efficient whole-house heating and cooling. Notably, you don't want a very tight, low-outdoor-air-exchange envelope and tons of insulation in your walls if you're going AC-free and not also trying to start a mold farm. And if you want efficient AC you don't want tons of huge, openable windows on every single wall, at the end of every hallway, in all rooms, et c, nor an open, breezy attic (which helps a ton with temp control if you don't have AC, but is just wasteful if you've got it) AFAIK design for minimizing AC power use and design for being able to tolerate not having AC are a "pick one, and only one" kind of thing. [EDIT] Oh, and not strictly related to AC efficiency, but it takes a lot more skill and care in material selection to build a house that won't have all kinds of problems after just a few years of natural outdoor temperature swings, in the molding, flooring, even wall alignment & finishes (drywall, mostly, these days), so of course no-one bothers anymore—let the interior hit 90s in the Summer, swinging a bunch day-to-night, with high humidity, and parts that aren't near your heating source reach below-freezing temps at night in the Winter, and your interior will age at least 5 years for every 1 actual year, thanks to damage from huge amounts of expansion and contraction, unless it's designed to account for that. Ditto with aligning houses for optimal airflow, as far as the direction they face. Why bother, since it's always gonna have whole-house AC and heating? So no-one does.
bootlooped 5y ago
In a previous apartment I had Jerry-rigged a whole-house/attic fan by putting a box fan in the space where the hatch to the attic was. I used triple-wall cardboard and duct tape to make it the right size. It really helped pull air in from every open window, and because it was at the top of the steps it helped exhaust the hottest air in the house. Box fans are not made for that type of application, but it worked. If I had to build my own again I would use a better fan, and use a smart home device to turn it on and off.
- daggersandscars 5y ago
  The version we had in the 1970s was basically this, but more industrial: a belt-driven fan in a minimal steel frame with a set of shutters that would open when the fan was on.
NamTaf 5y ago
Tonnes of places here in Australia have whirlybirds [1] installed on their roofs to achieve a similar outcome, if I'm understanding correctly. Basically, it helps draw out hot air when there's an outside breeze to spin it, cooling the ceiling cavity and overall decreasing the temperature of the house. [1]: https://duckduckgo.com/?q=roof+whirlybird https://duckduckgo.com/?q=roof+whirlybird
- ZeroGravitas 5y ago
  The results I clicked on suggested that a solar PV system and an electric fan to do the same task make a bit more sense these days. I think there's a few things like this where PV powered tech is probably the better option particularly as you can have one or the other running as necessary. Warm dark night: pump the hot air out with mains electricity. Cold, windy, sunny day: turn the fan off and use the electricity for something else.

ethhics 5y ago

From my previous research on whole-house fans, they are a wonderful device to have so long as you live in a place where the nights are cool, and most importantly, low-humidity. Unfortunately where I live and it’s 80+% RH at night, a whole-house fan would just give me mold.

handrous 5y ago
Modern US houses, at least in much of the country, aren't built to be livable or to survive themselves without year-round temperature control. Partly, this is because optimizing for building survival and inhabitant comfort without AC and with only limited heating is at-odds with designing for efficient whole-house heating and cooling. Notably, you don't want a very tight, low-outdoor-air-exchange envelope and tons of insulation in your walls if you're going AC-free and not also trying to start a mold farm. And if you want efficient AC you don't want tons of huge, openable windows on every single wall, at the end of every hallway, in all rooms, et c, nor an open, breezy attic (which helps a ton with temp control if you don't have AC, but is just wasteful if you've got it) AFAIK design for minimizing AC power use and design for being able to tolerate not having AC are a "pick one, and only one" kind of thing. [EDIT] Oh, and not strictly related to AC efficiency, but it takes a lot more skill and care in material selection to build a house that won't have all kinds of problems after just a few years of natural outdoor temperature swings, in the molding, flooring, even wall alignment & finishes (drywall, mostly, these days), so of course no-one bothers anymore—let the interior hit 90s in the Summer, swinging a bunch day-to-night, with high humidity, and parts that aren't near your heating source reach below-freezing temps at night in the Winter, and your interior will age at least 5 years for every 1 actual year, thanks to damage from huge amounts of expansion and contraction, unless it's designed to account for that. Ditto with aligning houses for optimal airflow, as far as the direction they face. Why bother, since it's always gonna have whole-house AC and heating? So no-one does.

bootlooped 5y ago

In a previous apartment I had Jerry-rigged a whole-house/attic fan by putting a box fan in the space where the hatch to the attic was. I used triple-wall cardboard and duct tape to make it the right size. It really helped pull air in from every open window, and because it was at the top of the steps it helped exhaust the hottest air in the house. Box fans are not made for that type of application, but it worked. If I had to build my own again I would use a better fan, and use a smart home device to turn it on and off.

daggersandscars 5y ago
The version we had in the 1970s was basically this, but more industrial: a belt-driven fan in a minimal steel frame with a set of shutters that would open when the fan was on.

NamTaf 5y ago

Tonnes of places here in Australia have whirlybirds [1] installed on their roofs to achieve a similar outcome, if I'm understanding correctly. Basically, it helps draw out hot air when there's an outside breeze to spin it, cooling the ceiling cavity and overall decreasing the temperature of the house. [1]: https://duckduckgo.com/?q=roof+whirlybird https://duckduckgo.com/?q=roof+whirlybird

ZeroGravitas 5y ago
The results I clicked on suggested that a solar PV system and an electric fan to do the same task make a bit more sense these days. I think there's a few things like this where PV powered tech is probably the better option particularly as you can have one or the other running as necessary. Warm dark night: pump the hot air out with mains electricity. Cold, windy, sunny day: turn the fan off and use the electricity for something else.