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U Value of a ground Floor over basement car park

  • 07-08-2009 10:24am
    #1
    ssssrrrr
    Closed Accounts Posts: 9 ✭


    Hi,
    I have an apartment which has a ground floor over a basement carpark and I don't know which way to calcualte the U value.

    I have drawings and I know that 390mm high density EPS is used.

    Do I calculate the U Value of the ground floor with the following formula ??

    U = lamda/(0.457B’ + dt) ??

    Then do I need to adjust the U value as its facing into an unheated space ??? The car park is open to the elements by the entrance??


    Help is much appreciated.

    SR


Comments

  • #2
    Count1
    Closed Accounts Posts: 52 ✭✭Count1


    hmmm, I working on a similar issue and am finding DEAP instructions a little confusing.

    Assuming it is an existing dwelling, I am in the floor section of building elements where it advises to check up on section 3.3 of DEAP maunual.

    The options on the dropdown menu would seem to be "exposed/semi exposed" or "Ground floor- above unheated basement"

    To me, it makes sense to enter it as "exposed/semi exposed" and because the apartment I am assessing is built 1994, I get a default of 0.6 u value.

    Not too sure if it helps you (especially considering you asked the question about a month ago! lol) but I can tell you it seems to be thrashing my rating to bits. I did a mid floor apt in same block and got a D2 but this one is coming in as an F.

    Admittedly, there is electric heating in both but it seems pretty poor for such a recent build.

    Any thoughts on my approach ( highlighted in BOLD) are appreciated.


  • #3
    Count1
    Closed Accounts Posts: 52 ✭✭Count1


    Any takers?............:confused:


  • #4
    ssssrrrr
    Closed Accounts Posts: 9 ✭ssssrrrr


    This is the SEI response,

    [FONT=&quot]For a new dwelling or if using non default U values for an existing dwelling (when you know the construction elements in the floor): [/FONT][FONT=&quot]This can be considered as an exposed surface adjacent to external air as per IS EN ISO 6946. Since the car park will be somewhat sheltered you could use an Rse value of .17 rather than the normal .04. Rsi can be taken as .17 and the layers of the floor will have their resistivity calculated from the thickness and conductivity as normal.[/FONT]



    So basicaly you calculate it like a normal ground floor but change the Rse value to 0.17


    Thanks for your input
    SSSSRRRR


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