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Percentage of air leakage in the house

airtight_ninja | Posted in Energy Efficiency and Durability on

Hi all!

I am trying to achieve PH standard airtightness (e.g. ACH=0.6 or q=0.06). To begin with, how much air is leaking from each part of a standard house? (If no airtight components are used)
 
I would like to know what percentage of air leaks from a standard house (e.g. 20% from around the foundation, 30% from the roof, 50% from windows and walls, etc…).
 
If anyone knows, I would like to know.
Best regards,
Airtight Ninja

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Replies

  1. DCContrarian | | #1

    There's really no such thing as a standard house.

  2. Walter Ahlgrim | | #2

    I agree no two houses are the same so the answer to your question is different for every house.

    .6 ach50 is an ambitious goal for new construction and all but unattainable as a retrofit.

    Would you want to tell us about your project?

    Walta

    1. airtight_ninja | | #3

      Thanks for the reply.

      I am trying to achieve the PH standard (.6 ACH) in my new house. (Climate zone 5A or 6A).
      At that time, I want to spend more money and build in areas where air leaks more easily. (Prioritize them).
      So I wanted to know the percentage of the air in my house that leaks from which places and how much.
      Sorry for the vague question.

      Best regards.

  3. Andrew C | | #4

    A couple of thoughts, since you appear to be in the design phase. Now is the time to buy a membership to GBA Prime so that you can access some of the good detailed information that's behind the pay wall. If you're new to building, a membership will pay for itself many times over.

    Search on this website (GBA) and at BSC's website for air barrier articles.

    To answer your question a bit more directly, houses don't tend to leak in solid planes much, they leak at intersections. From Info-408 document at BSC,
    "In building air barriers, the field of the opaque wall typically does not contribute strongly to the building’s overall air leakage. Instead, details that connect building components are often the cause of much of the air leakage, such as the roof-to-wall interface, wall-to-foundation interface, and other details (e.g., bathtubs, fireplaces, service penetrations)."

    The rim joist/wall-to-foundation interface (down low) and the uppermost ceiling (up high) are particularly critical for good sealing, partly because they're the farthest from the neutral pressure plane. Minimizing penetrations through the ceiling to the attic (canned lights, attic hatches in insulated ceilings, chimneys, etc) is a good place to start.

    Many of these articles come with links to other pertinent articles, so they should provide reading material for a least a day or so, and help you to perhaps refine your general question.

    Regards,

    1. airtight_ninja | | #7

      Thanks for the reply.
      Thank you for the detailed information about airtightness of houses.
      I will try to go to the BSC website and other information.

      Best regards,
      airtight ninja

  4. Expert Member
    Malcolm Taylor | | #5

    a-n,

    Andrew has given you good advice. If you are trying to reach an ambitious air-tightness rate, you will have to address all the problematic areas in the house. Trying to quantify which are most important doesn't yield much useful information.

    1. airtight_ninja | | #6

      Thank you for your reply.
      You say that it is important to improve the airtightness of the whole house.

      Best regards,
      airtight ninja

  5. W Ramsay | | #8

    What is your goal? Do you just want to be able to say you meet PH spec? Do you want to meet the stricter EU/International spec or the more lax US/Resnet spec? Do you want to reduce energy use? Overall cost of ownership (so spend less $'s on energy)?

    For the latter I've not seen a project in the U.S. where 0.6 is worth it, even a lax 0.6 Resnet as the cost for the last few % gets quite high. This can be different outside the U.S. depending on energy costs vs costs of materials and labor to achieve 0.6.

    1. airtight_ninja | | #9

      Thank you for your reply.
      I'll give it some thought.

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