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What makes an A rated house?

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  • 05-02-2018 12:18pm
    #1
    Mantis Toboggan
    Registered Users Posts: 17,683 ✭✭✭✭


    Hi,

    Most of the new builds currently seem to be A rated homes. Most seem to not have chimneys but most of the rest is standard ie standard double glazing windows, doors, standard blocks.

    My question is what makes these A rated homes and are these likely to be a rated homes in 10 years?

    Free Palestine 🇵🇸



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    #2
    Metric Tensor
    Registered Users Posts: 3,724 ✭✭✭Metric Tensor


    The definition is fairly easy - an A rated house is any house for which the DEAP software package calculates the house to have a primary energy usage of less than 75 kWh/m2/year.

    There are many ways of achieving this figure because the calculation is based on things such as insulation, air-tightness, type of heating, renewable energy contribution, etc. (but you are correct that reducing the number of chimneys usually helps!)

    They will stay A-rated unless either the 75 figure is changed by those in charge down the road or there is some drastic changes to what are called the "primary energy factors" used in the calculation.* (e.g. if for some reason Ireland's national grid got substantially less efficient, which is unlikely as it has been moving the opposite direction)


    * Or obviously if someone makes big changes to the house.


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    #3
    Mantis Toboggan
    Registered Users Posts: 17,683 ✭✭✭✭Mantis Toboggan


    Perfect thanks.

    So with these houses yet to be built they will have shown that the materials being used will achieve an A rating?

    Free Palestine 🇵🇸



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    #4
    Metric Tensor
    Registered Users Posts: 3,724 ✭✭✭Metric Tensor


    That's the theory .....

    If you search this forum you'll see many examples where a house has a nominal A rating but does not behave that way.

    With the exception of the requirement for an Air Tightness test there is no inherent check in the BER of the quality of construction. So a sh!t quality house with the same materials as a well built one will have more or less the same rating. (AT test being the one possible "check")


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    #5
    Gumbo
    Moderators, Society & Culture Moderators Posts: 38,526 Mod ✭✭✭✭Gumbo


    Tyson Fury wrote: »
    Hi,

    Most of the new builds currently seem to be A rated homes. Most seem to not have chimneys but most of the rest is standard ie standard double glazing windows, doors, standard blocks.

    My question is what makes these A rated homes and are these likely to be a rated homes in 10 years?

    Just a correction, that all new builds must be A rated by default through our Building Regulations and minimum standards.

    Developers use the term "A" rated as a selling point....Its like a motor dealer advertising his car with "Disc Brakes" :)


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