Do Energy Efficient Homes Cause Asthma?

Asthma-energy-efficient-home-ventilation-guardian

The British newspaper The Guardian recently published an article on asthma and energy efficient homes, claiming that reducing energy use in homes can hurt indoor air quality (IAQ). But wait! Asthma may not be the only thing to fear with energy efficient homes. A researcher whose report is cited says that poor IAQ also can lead to “lung cancer, chronic obstructive pulmonary disease, airborne respiratory infections and cardiovascular disease.” Should we be worried? Are those airtight houses going to kill us?

The British newspaper The Guardian recently published an article on asthma and energy efficient homes, claiming that reducing energy use in homes can hurt indoor air quality (IAQ). But wait! Asthma may not be the only thing to fear with energy efficient homes. A researcher whose report is cited says that poor IAQ also can lead to “lung cancer, chronic obstructive pulmonary disease, airborne respiratory infections and cardiovascular disease.” Should we be worried? Are those airtight houses going to kill us?

The mythology lives on

I found out about this article when Elrond Burrell, an architect and blogger in the UK, posted a link to it on LinkedIn the other day. He actually showed a revised version of the screenshot you see above because that title is misleading, as indicated by the subtitle.

If you’ve been reading the Energy Vanguard Blog for a while, you know what the problem is here. I’ve written about it over and over. In fact, one of the very first articles I wrote here back in 2010 was on this topic, the misguided idea that “a house needs to breathe.”

No, a house doesn’t need to breathe. No, energy efficient houses don’t cause asthma. No, the problem isn’t that we’re making houses more airtight.

The subtitle in the screenshot tells you what the real problem is:  lack of ventilation. Oddly, they attribute the lack of ventilation to better insulation rather than, say, the fact that no one thought to install a ventilation system. Not only are they confusing the building enclosure control layers (insulation limits the flow of heat; the air barrier limits the flow of air), but they also missed that mechanical systems are a separate component and not part of the building enclosure.

Sadly, The Guardian is propagating the same old confusion with this article. I know not everyone can be a building science expert, but this is pretty basic. And look, a lot more people are getting sick because of poor indoor air quality in homes that are not energy efficient in the least. Here are a few reasons why:

  • Leaky homes over moldy crawl spaces or basements let bad air into the house.
  • Duct leakage brings bad air into the house, sometimes from a dead possum.
  • Moisture problems from flashing cause mold to grow in walls.
  • Unvented space heaters add lots of water to the indoors, growing mold on the walls.

According to a 2007 study on asthma and mold, “Of the 21.8 million people reported to have asthma in the USA, approximately 4.6 (2.7-6.3) million cases are estimated to be attributable to dampness and mold exposure in the home.” In other words, fix the moisture problems.

Airtight homes need mechanical ventilation

OK, let me say this again:

Airtight homes need mechanical ventilation!

I’ve written on this topic a lot. When you seal up a home, you have a better chance of achieving good indoor air quality than you do with a leaky home, but you have to do two things:

  1. Reduce the sources of indoor air pollutants (source control)
  2. Install a whole-house mechanical ventilation system (dilution)

The ventilation system will dilute the indoor pollutants, but a ventilation system with a reasonable ventilation rate can easily be overwhelmed if you fill the house with toxic stuff. The article in The Guardian actually mentioned this when they wrote, “…it is important to ensure that adequate ventilation levels are maintained and indoor air pollution sources minimised to protect public health.”

It turns out, people have known this for a long time:

“If there is a pile of manure in a space, do not try to remove the odor by ventilation.
Remove the pile of manure.”

~ Max von Pettenkofer, 1858

Again, the problem is not energy efficiency or airtightness. It’s a lack of understanding that a house is a system. In fact, airtight, energy efficient houses can be much more healthful than inefficient, leaky houses.

 

Related Articles

Myth: A House Needs to Breathe

Asthma and Poor Indoor Air Quality — The Trouble with Homes

Why Do Airtight Homes Need Mechanical Ventilation?

 

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This Post Has 20 Comments

  1. Thanks for the response
    Thanks for the response Allison, it is very annoying how these misleading articles get out there. I had contact with the editor of another recent one (http://www.thelocal.no/20150701/eco-homes-cause-asthma) and they added a quote from me which improved it, but still didn’t get my quote right!

    I agree that airtight buildings need mechanical ventilation, but not strictly because they are airtight –
    a) It is possible to ventilate airtight buildings using opening windows, if operated correctly and the climate is favourable. (Neither very likely in most scenarios, though!) For example, there are passivhaus buildings in the UK that rely on window ventilation in summer only. As far as I am aware, they are OK for summer IAQ, although not as good as mechanically ventilated ones.
    b) Very leaky buildings ventilated via windows and trickle vents have been shown to have unacceptable IAQ. Probably because the leakage/infiltration is inadequate to provide ventilation, for a variety of possible reasons (not that it should!) and probably because people don’t operate windows correctly to provide adequate ventilation.

    On the other hand, if you want efficient heat recovery, you definitely need an airtight building!

    The old adage – " build tight, ventilate right" – is still valid!

  2. Good things come form things
    Good things come form things done correctly.

  3. I am s trained respiratory
    I am s trained respiratory therapist and your right that’s all bunk.

  4. Thanks for the response
    Thanks for the response Allison, it is very annoying how these misleading articles get out there. I had contact with the editor of another recent one (http://www.thelocal.no/20150701/eco-homes-cause-asthma) and they added a quote from me which improved it, but still didn’t get my quote right!

    I agree that airtight buildings need mechanical ventilation, but not strictly because they are airtight –
    a) It is possible to ventilate airtight buildings using opening windows, if operated correctly and the climate is favourable. (Neither very likely in most scenarios, though!) For example, there are passivhaus buildings in the UK that rely on window ventilation in summer only. As far as I am aware, they are OK for summer IAQ, although not as good as mechanically ventilated ones.
    b) Very leaky buildings ventilated via windows and trickle vents have been shown to have unacceptable IAQ. Probably because the leakage/infiltration is inadequate to provide ventilation, for a variety of possible reasons (not that it should!) and probably because people don’t operate windows correctly to provide adequate ventilation.

    On the other hand, if you want efficient heat recovery, you definitely need an airtight building!

    The old adage – ” build tight, ventilate right” – is still valid!

  5. Good things come form things
    Good things come form things done correctly.

  6. I am s trained respiratory
    I am s trained respiratory therapist and your right that’s all bunk.

  9. I recently had the craw space
    I recently had the craw space of my home Encapsulated. Closed cell foam was sprayed on the walls. The work was completed in July of this year (2015). I can smell a smell in the house now that was not present before the foam was sprayed in the crawl space. Can someone tell me if the odor is harmful to my family’s health.

  10. I recently had the craw space
    I recently had the craw space of my home Encapsulated. Closed cell foam was sprayed on the walls. The work was completed in July of this year (2015). I can smell a smell in the house now that was not present before the foam was sprayed in the crawl space. Can someone tell me if the odor is harmful to my family’s health.

    1. It is hard to diagnose smells
      It is hard to diagnose smells without a lot more information! I would recommend starting with the original installer, but if your concerns are not addressed, going to an independent expert to evaluate your concerns; engineer, licensed contractor, home inspector, etc. I have recent experience seeing retrofit encapsulations with issues, so my first question is: were all sources of exterior water infiltration to the crawl resolved before encapsulation? Encapsulation to deal with high moisture levels in the crawl, without thoroughly addressing moisture infiltration, is bound for failure.

    2. In my research, I have read
      In my research, I have read this many times. I was going to use the closed cell insulation esp. in the crawl space as well as a layer in the walls, eves, etc. but after reading about the egg smell, I will not. I have read that plastic should be used under the rat slab… this is to prevent moisture from penetrating the cement. Cement has a lot of water in it anyway, but eventually dries. The moisture from the ground below it will be wicked up into the cement.

  11. The odor could be coming from
    The odor could be coming from the plastic used to encapsulate the crawlspace floor or from the foam material used for insulation. Properly mixed and properly applied foam insulation technically should have no odor although I have heard many complaints of odors for several months after application. There is no way to know if the odor is harmful to your family. I would contact the crawlspace mitigation company and ask them for a solution then of nothing there call the manufacturer of the products used in the installation and complain about the odor. I know of several cases in which the manufacturer had to pay to remove their product from someone’s home due to an offensive odor generated by the misapplication of their product.

  12. The odor could be coming from
    The odor could be coming from the plastic used to encapsulate the crawlspace floor or from the foam material used for insulation. Properly mixed and properly applied foam insulation technically should have no odor although I have heard many complaints of odors for several months after application. There is no way to know if the odor is harmful to your family. I would contact the crawlspace mitigation company and ask them for a solution then of nothing there call the manufacturer of the products used in the installation and complain about the odor. I know of several cases in which the manufacturer had to pay to remove their product from someone’s home due to an offensive odor generated by the misapplication of their product.

  13. It is hard to diagnose smells
    It is hard to diagnose smells without a lot more information! I would recommend starting with the original installer, but if your concerns are not addressed, going to an independent expert to evaluate your concerns; engineer, licensed contractor, home inspector, etc. I have recent experience seeing retrofit encapsulations with issues, so my first question is: were all sources of exterior water infiltration to the crawl resolved before encapsulation? Encapsulation to deal with high moisture levels in the crawl, without thoroughly addressing moisture infiltration, is bound for failure.

  14. In my research, I have read
    In my research, I have read this many times. I was going to use the closed cell insulation esp. in the crawl space as well as a layer in the walls, eves, etc. but after reading about the egg smell, I will not. I have read that plastic should be used under the rat slab… this is to prevent moisture from penetrating the cement. Cement has a lot of water in it anyway, but eventually dries. The moisture from the ground below it will be wicked up into the cement.

  15. After reading all of these
    After reading all of these comments about air tightness, I am wondering about using a ventless fire place in a home I’m building. The women at the fireplace store said they were 99.9% efficient. The vented ones only about 70%. I put ventless heaters in a shore house I have had for years. Sadly the attic was insulated by never vented. We purchase it that way but never had a problem. When we went up there to retrieve some items stored, after installing the heaters, the whole attic was filled with mold. Meaning, a lot of moisture was being put into an already humid environment (we are near the beach and bay). Is this only because of the lack attic ventilation or is it going to be a problem if I install ventless in a new house? I’m not sure what to do.

  17. After reading all of these
    After reading all of these comments about air tightness, I am wondering about using a ventless fire place in a home I’m building. The women at the fireplace store said they were 99.9% efficient. The vented ones only about 70%. I put ventless heaters in a shore house I have had for years. Sadly the attic was insulated by never vented. We purchase it that way but never had a problem. When we went up there to retrieve some items stored, after installing the heaters, the whole attic was filled with mold. Meaning, a lot of moisture was being put into an already humid environment (we are near the beach and bay). Is this only because of the lack attic ventilation or is it going to be a problem if I install ventless in a new house? I’m not sure what to do.

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