GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Reverse air conditioning?

mgirard | Posted in Energy Efficiency and Durability on

We live near the Pacific Ocean, where the climate is cool (average about 60-65) year-round. In locations where the sunlight is unfiltered, the light can be quite intense and create a lot of heat. So on a normal day, our attic can be extremely hot–over 100–while the house remains very chilly. Because we have good insulation in the attic, that heat does not come into the house.

It seems to me that there should be a way to pull that daytime attic heat (the attic is very clean) down into the house, but I have not been able to find out how to do that.

Any ideas?

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    You could install a couple of ducts into your attic, and install a couple of inline fans, and circulate air between your attic and your house if you wanted to.

    I think you would discover that:

    (a) the temperature of the air would drop quickly as the attic air is replaced by a mixture of outdoor air and house air, and

    (b) the value of the heat would be so low that it wouldn't justify the investment in equipment needed to harvest it, nor the cost of the electricity needed to run the fans, and

    (c) the ducts would create undesired holes in your ceiling that would leak heat during cold weather.

    Instead of implementing your scheme, you might consider adding another window or two on the south side of your house.

  2. heinblod | | #2

    There are 'dry' ST collectors propelling warm air into the building. Here a sample, there are many more on the market:

  3. user-917907 | | #3

    If you at all DIY-oriented, the Build It Solar site has a wealth of information geared towards simple, effective solar thermal collectors

  4. GBA Editor
    Martin Holladay | | #4

    Researchers have measured the performance of solar air collectors, and the amount of heat they gather is not enough to justify the investment in the equipment required to gather the heat.

    Moreover, solar air collectors only collect heat when the weather is sunny. And when the weather is sunny, your house doesn't need any heat -- because the sun will always keep your house warm enough when the sun is shining (assuming that your house has an adequate number of south-facing windows and has a tight, well-insulated thermal envelope).

  5. user-917907 | | #5

    If I read Maureen's post correctly, she says that even on sunny days her house is often cool. So it appears to me that she might be an ideal candidate for a solar heat collector. I also suggested that solar might work for her IF she were DIY-oriented. Many of the air collectors that are featured on Build It Solar claim they are almost as efficient as commercial units, and are FAR less expensive. Props to them!

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |