01746 862 640

Heat loss around windows - thermal bridging

Heat loss around windows is a big issue in old solid walled buildings.  It becomes more of a problem in Listed Buildings, because it is often hard to make physical changes to conserve heat, without having to get Listed Building Consent for changes.  In the images here, the first shows an old stone wall, with insulated steel framing internally.  Where the steel frame meets the window, plasterboard has been fixed directly to the stone.  It looks fine at first glance, but with the imaging camera you can see where the plasterboard cement is thermally bridging to the stone, and causing heat loss. 

In the other two pictures, heat is leaking out around the UPVC windows fitted in a very thick stone walled Welsh cottage - the windows themselves are fine - very little heat loss there - but the actual wall is losing heat where it is thin - around the windows.  Taking the existing plaster off around the window, and replacing it with an insulating hemp lime mix will add thermal resistance to the reveal, and stop heat loss. 

Thermal bridging through plasterboard 'dab' cement in a window reveal. To the left is steel framing, with insulation - working well.  Heat is being lost through the plaster dabs close to the window.

Thermal bridging - heat loss - close to the edge of a new UPVC window in a stone cottage.  Where the stonework is thin - and close to outside, heat is able to leak around the window frame.  This reveal needs insulating with a hemp lime mix. 

Thermal bridging - heat loss - at the edge of a new UPVC window in a stone cottage. The stonework is thin - and close to outside, heat is able to leak around the window frame.  This reveal needs insulating with a hemp lime mix. 

Regulated by RICS