Domestic Thermal Imaging Survey

In January 2010 we commissioned a thermal imaging survey of our house. This gave us a useful insight into where we're loosing heat.

Our house is a traditional 1930's three bedroom detached property in Nottingham. The walls are brick with no cavity. It's never been particularly cozy. In cold snaps we do well to get the temperature up to the high teens centigrade. Since we moved in in 1997 we've gradually replaced all the windows and exterior doors with double glazing. This piece meal process was completed this winter but I was a bit disappointed that the house was still chilly. Out of frustration I decided to pay for a heat loss survey. I found East Midlands Thermal Imaging Ltd. – a company based just down the road in Trowell, Nottingham – via a Google search. All inclusive cost for a domestic survey is £175. The report is delivered on a CD-ROM (paper copy £25 extra).

The survey took the best part of an hour to complete. I had expected that most of the time would be spent outside the house but the reverse is the case.

The thermal imaging camera is an amazing piece of kit. David demonstrated how sensitive it is by putting his hand on the carpet for one second. The camera showed a distinct hand-print with no sign of it dissipating before we moved on. A top-end device like this costs about £20,000.

It was interesting to hear David's opinion of new houses. He would never buy one. You would think that the combination of modern building regulations and an increasing emphasis on fuel efficiency would mean that new houses were better insulated than ever before but apparently this isn't the case. David receives a lot of business from people who have purchased a new house and then become suspicious that they're not up-to-scratch (insulation wise). They get David round to do a survey before the guarantee runs out (typically 10 years) and then use the report to help make a claim. The house builders must love him!

David also does a lot of business surveying electrical gear for factories. Certain types of electrical component get hotter when they begin to wear out. Using thermal imaging to detect these before they actually fail is a form of pre-emptive maintenance. The cost savings can be significant when you consider that production lines might otherwise have to shut down while waiting for an electrician and new parts. Worse, electrical problems can lead to fires.

Anyway, I digress. David's survey of our house highlighted the following, some of which was expected and some of which was a surprise:

• Inside survey:
  • Missing loft insulation.
    Thus picture is looking up at the ceiling, with an exterior wall in the bottom left of the picture. Note how easily you can see where there are gaps in the loft insulation!
  • As we suspected, significant heat loss through the exterior walls.
  • Various thermal bridges in corners between external walls.
  • Thermal bridges due to metal low threshold strip under uPVC doors.
  • Heat loss around window frames.
  • Uninsulated flat roof areas, e.g. above oriel bay window in upstairs bedroom.
  • Cool air entering hallway from the cupboard under the stairs.
  • Air bricks allowing cool air into house.
• Outside survey:
  • Significant heat loss through the exterior walls.
  • Radiators mounted on external walls are radiating a lot of heat straight through the wall.
  • Heat loss around window frames.
  • Air bricks leaking a lot of heat (David's not convinced they're worth leaving open - worth experimenting).
  • The ceiling within front door porch area in front of the front door is very poorly insulated. (For some reason I'd never imagined that a downward facing surface could be such a big source of heat loss.)
  • Roof is not too bad, apart from around the old chimney at the back of the house and above the bathroom. (We'd already noticed that snow was melting quickly above the bathroom compared to the rest of the roof.)

If you're interested to see all the detail, download the full report.

What we plan to do as a result of this survey:

1. Fit reflective film behind all exterior wall mounted radiators.
2. Fill the gaps in the lost insulation, and probably double the depth of insulation overall while we're at it (since David reckons we're well below what's currently recommended).
3. Insulate the porch roof.
4. Maybe fit some insulation behind the wallpaper on external walls when we next redecorate.
5. Try blocking or limiting the airflow through the air bricks.
6. Get some of those retro door snakes to go at the bottom of the doors.