how can i calculate u value for an Uninsulated conc. floor

mail

I would like to know how to calculate the U value for an Uninsulated concrete floor for a house that was built thirty years ago, i tried the part L but cant find it there ,any help appreciated

Paterson

do you know what thickness the floor is? ish?

mail

yes its approx. 100 mm without any insulation around the edge or in the floor.

BryanF

" the thermal resistance of dense concrete slabs and thin floor coverings may be ignored in the calculation and that the thermal conductivity of the ground should be taken as 2.0 W/mK unless otherwise known or specified" TGDpL 2007 p41

http://www.environ.ie/en/DevelopmentandHousing/BuildingStandards/RHLegislation/FileDownLoad,16556,en.pdf

Mellor

BryanF wrote: »

" the thermal resistance of dense concrete slabs and thin floor coverings may be ignored in the calculation and that the thermal conductivity of the ground should be taken as 2.0 W/mK unless otherwise known or specified" TGDpL 2007 p41

http://www.environ.ie/en/DevelopmentandHousing/BuildingStandards/RHLegislation/FileDownLoad,16556,en.pdf

That refers to ignoring the conductivity when calculating an overall buildup. For example, when the concrete is to the cold side of floor, it behaves like external ground and is already counted.

The OP need something to compare

mail wrote: »

I would like to know how to calculate the U value for an Uninsulated concrete floor for a house that was built thirty years ago, i tried the part L but cant find it there ,any help appreciated

It's in part L.
There is a table that gives various values of standard building materials, and the method is also in part L.
I'm not sure what your trying to achieve though, there really is nothing to gain by calculating this value, its going to be way ay off limits. So much so that is it irrellevant imo

mail

Thanks for the replies, this is for a project doing a survey on an old house, should I calculate the floor as if it has insulation and then deduct it out when adding up the elementry U values at the end. I know there are tables but I have to show how I done the calculations.

sydthebeat

another option may be to apply the default u values for that aged building in accordance with the 'existing buildings' of DEAP.