Sustainable Cottenham – Thermal imaging

Thermal imaging reveals hidden home heat loss

The fuel and climate crises have increased awareness of the cost of heating our homes, both financial and environmental. Many of us wish to take positive steps to reduce our use of fossil fuels. Improving the thermal properties of our homes is often the quickest and most cost effective way to do this.

So where do the draughts come from? What can you do about them? How much heat escapes through the walls/windows/roofs? You can find out these things through the lens of a thermal imaging camera which looks at the barrier between the warmer inside and cooler outdoors, be it walls, windows, ceilings or doors. Both normal pictures and thermal images identify in brilliant technicolour where improvements may be needed. Rob Moorcroft who volunteers with Sustainable Cottenham visited houses in the village this winter with a camera on loan from Cambridge Carbon Footprint. Anyone who lives in South Cambridgeshire and has attended training can borrow a camera, but demand is high so they must be booked in advance.

Many houses in the UK were built pre-1911, and 75% of houses built before 2010 require improved insulation. The older the house, the more likely the roof, walls and windows will need some kind of additional insulation or retrofitting, or simple DIY improvements to be truly energy efficient. Insulation and draughtproofing are key. These of course cost money to install, but are likely to be offset by a reduction in your heating bills.

The camera identifies the insulating properties of the thermal envelope of your property. Warmer parts show up as reds, oranges and yellows while cooler areas appear as purple or blue. When viewing the house from the outside, the warm red sections need insulation. Vice versa when imaging at external walls from the inside the house. An example of a thermal image alongside the corresponding photograph can be seen in Figure 1, viewed from an unheated garage (from outside). The wall on the left has insulating board, so the wall appears cool, however on the right, the red/yellow shows that the wall is warm, and therefore heat is being transferred from inside to out. This wall would benefit from insulation, which would reduce heat loss from the home.

Figure 1: Photograph and thermal image of an external wall from the garage. The left hand side of the wall has good thermal properties, the right side may benefit from some kind of wall insulation.

Greenpeace estimates that in a standard un-insulated house, 35% is lost through the walls, 25% through the roof, 10% percent through the windows, and 30% percent between floors and draughts.

Insulating the roof space will benefit the whole house, and the cost varies, however this often has the greatest payback if current insulation levels are insufficient (current recommendations are for 30 cm Rockwool). Wall insulation is a must, since walls commonly have the largest exposed surface area. Costs vary depending on the size of your home and method of insulation. Exterior insulation for solid walls can be expensive (the Mortgage Advice Bureau puts the average cost for a semi-detached at £9,000, mid terrace at £7,000). There are also options for internal walls: thermally backed plasterboard is very effective and doesn’t change the look of the house. Thermal wallpaper is a low cost option which has a negligible impact on internal space.

Upgrading windows and doors will mean fewer cold spots. For a lower cost DIY option, secondary glazing (an additional sheet of polycarbonate) provides an excellent thermal barrier and can be an effective way to improve the thermal properties of single pane windows in conservation areas. This keeps heat in, as well as letting the light in. Other options include thick, thermal-lined curtains and self-adhesive draught excluders.

To find out about thermal imaging cameras and training visit For advice on home insulation and available grants, visit

By Wendy Dear

Next Cottenham village litter pick – 29 April 2pm

Our next village litter pick will be on Saturday 29th April. Meet at Cottenham Village Hall, Lambs Lane Recreation Ground at 2pm where equipment and routes will be provided. See our facebook page for more details.