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

Oxygen intake for a highly airtight home

Koichan | Posted in General Questions on

Hi.  I just discovered this community, and am I glad!  I have been wondering about the oxygen supply for my Energy Star house.

I recently discovered a mold problem at my house with white mold on my furniture.  My mold remediation company started to run a dehumidifier along with my AC with all my windows closed to prepare for their cleaning.  That makes sense to lower the indoor humidity because I live in Atlanta where we have a very muggy summer.  But I am concerned about the lack of fresh air intake while running a dehumidifier.  I am planning to use a dehumidifier as a permanent solution for lowering indoor humidity.  I don’t have an active ventilation system, just exhaust fans in the bathrooms and the kitchen.  This is a 2000-sqft. house with one person, one cat, one fish, a computer and plants.  Is there a danger of depleted oxygen in the house for that solution with closed windows all summer?  Thank you in advance for your comments.

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

    Briefly, the answer is that there is no danger that you will deplete the level of oxygen in your home to dangerous levels. (Air is about 21% oxygen.) However, there are conditions where indoor levels of carbon dioxide can rise to the point where clear thinking is (possibly) affected. You are aiming to achieve 1000 ppm of CO2 or less.

    For more information on ventilation -- which is a huge topic -- see the many articles listed on this page: "Ventilation."

  2. Expert Member
    BILL WICHERS | | #2

    Your dehumidifier won’t do anything to affect oxygen levels in your home. Dehumidifiers work by making a cold surface and condensing water out of the air. The only thing the dehumidifier will do is remove moisture from the air (some of the moisture, not all of it), and add a little heat into the space. Dehumidifiers do not alter the atmospheric gas makeup (oxygen, carbon dioxide, nitrogen, etc).


    1. Jon_R | | #3

      In other words, if you were happy with air quality with just AC, you will be even happier with AC + dehumidifier.

  3. Koichan | | #4

    Thank you all for your comments. I hope this is my last question on this topic. what is an easy way to purge carbon dioxide without a high energy penalty? would it be sufficient to open windows whenever you can when the temp and humidity outside are low, or crack windows even the temp and humidity are high outside?

  4. exeric | | #5

    I agree with Martin and Bill (Zephyr). In a hot humid climate one really should keep the windows closed and use AC. AC is already a dehumidifier and if you need a dehumidifier in addition then you've probably got other structural problems in addition. But you live in the deep south where it's just stacked against you in summer. Ordinarily a dehumidifier seems just a band-aid if it's used in addition to AC.

    Keeping all the windows closed in outside hot muggy conditions just seems like good sense. In a situation like that an ERV is a good investment to decrease the CO2 buildup. They can be expensive initially but they won't consume a lot of electricity like a dehumidifier would. I lean towards the idea that there is something ineffective with the AC to need a dehumidifier if its in addition to AC. If the dehumidifier stands alone then that's a different story. Then go for it.

    Edit: due to the fact that I didn't see he actually lives in the deep south.

  5. GBA Editor
    Martin Holladay | | #6

    Koichan and Eric,
    I might have misunderstood, but it sounds as if Eric's response implied that the use of an ERV can lower indoor humidity levels. It can, but only in winter. In hot, humid weather, an ERV won't lower indoor humidity levels. Only an air conditioner or a dehumidifier can do that.

    Q. "What is an easy way to purge carbon dioxide without a high energy penalty?"

    A. What you need is a ventilation system. "Easy" means inexpensive -- for example, a central-fan-integrated supply ventilation system or an exhaust-only system. But "easy" is in conflict with your other criterion: "without a high energy penalty." For the lowest energy penalty, you want an HRV or an ERV -- and that costs a lot to install (and is therefore probably not "easy").

    All of your options are laid out in the following two articles:

    "Designing a Good Ventilation System"

    "Revisiting Ventilation"

    1. exeric | | #7

      No, I was answering off the implied info that keeping windows closed would decrease humidity in combination with an AC or a dehumidifier. Doing that in turn would increase CO2 levels. So it's best to use a ERV to get fresh air without increasing humidity. Also I suspected that perhaps opening windows was increasing the humidity inside and if he doesn't do that then he might not need a dehumidifier. I'm not there but that was my hope.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |