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Thermal Imaging Surveys

Our image surveys for 2013 are now complete and we are handing over the camera to the next group. If you have received a survey and would like some tips on your pictures and links for dealing with heat loss, read on...!

What will thermal imaging show me?

If you receive a visit during our campaign, you will receive a set of photographs and usually a discussion with the surveyor who will help identify areas where you can save energy.

It is important to understand just what the photos do and do not show, as the results need careful interpretation, and in particular the colours that you see depend on how the operator has set the camera.  The temperature:colour relationship is usually set to accentuate any anomalies, which means that the minimum (dark blue) and maximum (red to white) temperatures will vary according to what is being looked at.  So the same picture taken with different camera settings may give different impressions  of what is going on!

The picture will give the colour:temperature scale, and can sometimes be hard to interpret as it relates to the surface temperature only, and may also be affected by reflections and rain. 

So in short, the pictures you receive should be looked at in a qualitative way, with their main purpose being to show anomalies, usually small problems that you may be able to fix.  You won’t be able to assess how good your wall or loft insulation is in absolute terms, but then you don’t need thermal imaging to tell you that this is a good thing to do.

To get an idea of how good your house is in general terms, it is worth comparing it to neighbouring houses.  This will for example quickly show how your loft insulation compares.

Tips on interpretation

Radiator shaped “glows” on the walls show that heat is escaping from the back of the radiator.  This can be reduced by attaching foil to the wall behind it.

Long thin glows are likely to be hot pipe runs.  If they are in the wall cavities, there is nothing straightforward that can be done, but if they are exposed then they can be lagged.

Lighter areas in roof spaces indicate damaged loft insulation, which was perhaps disturbed by activity in the loft.  Sometimes small areas of roof over porches etc may have inferior insulation.

Hot spots in the roof are usually due to extractor fans.  Look for jammed open fan vents from the kitchen and bathroom, as these are like a hole in the wall and can lose a lot of heat.

Cat flaps are a perpetual problem and may be worth updating if broken or not closing correctly. If you no longer have a cat it is worth blocking off properly.

Letterboxes and keyholes can leak. You can get simple devices that reduce this greatly.

Leakage around doors can be a problem, and here draught-proofing strips should be installed.

The glass in front doors is usually only single pane, and so is a heat loss. May be hard to do much about but a thick curtain will certainly help.

Sometimes patio doors are found to be worse than other windows. 

Don’t worry about small heat losses at the top of windows, This is most likely to be a small draught strip that is now part of the Building regulations.  Leakages elsewhere may indicate a poorly fitting window, which may benefit from an additional draughtproofing strip.

For more information about dealing with energy loss visit the Energy Saving Trust’s website:










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