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Air tightness measurements & ideal target

  • 11-01-2016 10:03PM
    #1
    MizMix
    Registered Users, Registered Users 2 Posts: 313 ✭✭


    Finalising tender and spec as per previous posts. Can someone advise if current regulations are: 7 m3/(h.m2) or is it now 5 m3 ?

    In terms of a good level of airtightness for MHRV is 4 m3 good enough? Or should it be lower?

    Does this performance measurement equate to a specific ACH measurement or is it measured separately? I.e. what is 5m3 in ACH? And what is the m3/(h.m2) and ACH that we should reach for a MHRV? (asking for both as different suppliers seems to refer to the different performance measurements). I understand as low as possible is best but I'm presuming at some point (getting closer to passive) that the cost to achieving any higher starts getting higher (diminishing returns so to speak).

    Thank you


Comments

  • #2
    MicktheMan
    Registered Users, Registered Users 2 Posts: 2,952 ✭✭✭MicktheMan


    ACH and m3/hr/m2 are nearly interchangeable for most houses (generally within 10% of each other).
    Official units here is the permeability in m3/hr/m2. ACH is used in other countries.

    Now the target. On a newbuild I would target sub 1 m3/hr/m2. Why? Because if the builder commits to this target then you know he knows his onions and the chances of the quality of the rest of his work (and trades he brings on site) should be equally good. You also need to have an architect who is clued in so that he/she designs for good airtightness.


  • #3
    galwaytt
    Registered Users, Registered Users 2 Posts: 12,754 ✭✭✭✭galwaytt


    MizMiz - both 7 and 5 are poor, and imho, so is 4. Our highest reading we've ever seen was 3.25, and that was 8 years ago.

    We are currently seeing client houses between 0.49 and 1.2.

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • #4
    MizMix
    Registered Users, Registered Users 2 Posts: 313 ✭✭MizMix


    Thanks both- more curious as to what current regs are as quite a few contractors I've spoken to are not confident exceeding regs. However that being said we met a great builder this weekend, visited a reference house he has just built, and everything he builds is to 1 m3 min. I guess I just wanted to understand if this is a performance only specialist builders are reaching....if those specialist builders price the job way out of budget then what's a realistic target for a more 'regular' contractor. It's sounds though that actually 1m3 should be achievable for a competent builder


  • #5
    galwaytt
    Registered Users, Registered Users 2 Posts: 12,754 ✭✭✭✭galwaytt


    "not confident exceeding regs" - cough - splutter.

    Then you need different builders. The regs values are abysmally low. If they can't better that, then they don't know what they're doing. Getting ahead of regs is not 'specialist' - it's just doing the job properly.

    Interestingly, the airtightness target for a school building is twice as good as the backstop Regs value for a house.

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



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