Concrete @ your Fingertips


Insulation and U values

Dense concrete has a large thermal mass and it is not a particularly good insulator. In winter weather conditions, the temperature differences between the interior and exterior of a structure can lead to significant heat losses unless properly insulated, airtight and efficiently designed. Retaining as much heat as possible in the structure in cold weather conditions, to reduce the environmental impacts associated with heating a building, is important. It has been estimated that 27% of the UK total CO2 emissions are from domestic heating. It is for this reason the Building Regulations (Part L1: ´Conservation of fuel and power in dwellings´) have been changed and now require lower U-values.

U values for various building elements.

Exposed element
Pitched roof with insulation between joists...................0.16 W/m2K
Flat roof....................................................................0.25 W/m2K
Walls including basement walls............................. ....0.35 W/m2K
Floors, including ground floors and basement floors......0.25 W/m2K

For further information see U-values: understanding heat movement, published in CONCRETE in March 2003, pp 42–43. Copies are available as a free download from the Members Area of the Concrete Society web site.


Acknowledgement: UKQAA