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Sadberge Energy Saving Project

INFRA-RED PHOTOGRAPHS

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During February 2009, members of the Climate Change Working Group offered to take infra-red photographs of houses in Sadberge so that householders could see how much heat their homes were losing through roofs, walls and windows.

Thumbnails of some of these thermal images are shown below.  Click on any thumbnail to see a larger version of the relevant picture.

How does your house compare with others in Sadberge?  Click on this link to see the temperature distribution graphs for the participating houses.

See further down this page for notes about infra-red photographs.

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Notes
(1)  The infra-red photographs were taken on the evening of Monday 23-Feb-2009.
(2) A standard 'colour palette' has been used to display temperatures on a scale from 8C to 14C, so you can make direct comparisons between different infra-red photographs.
(3)

The infra-red camera estimates the temperature of each surface by measuring the amount of infra-red radiation coming from that surface.  However, the infra-red radiation from a surface includes both (a) the infra-red radiation emitted by the surface and (b) the infra-red radiation reflected by the surface.

For a shiny, reflective surface, the infra-red camera basically sees the infra-red radiation reflected from the surface, which is independent of the temperature of the surface itself.  For a "mirror finish" roof, the infra-red camera would just see the reflected infra-red radiation from the night sky.

For a very rough surface, there is very little reflected infra-red radiation and the infra-red camera basically sees the infra-red radiation emitted from the surface, which is a good indication of its temperature.

For houses, most surfaces are somewhere between these two extremes.  Some of the infra-red radiation coming from the surface is reflected from the sky, but most is emitted by the surface.  For the infra-red photographs of Sadberge houses, we have assumed that all surfaces have an 'emissivity' of 0.95.

Also, some of the infra-red radiation coming from a surface is absorbed by the air between the surface and the infra-red camera.

Therefore, please be aware that the infra-red images of Sadberge homes are only estimates of the temperatures of the various parts of the buildings.  In particular, they rely on assumptions about the roughness of the various surfaces, the 'temperature' of the infra-red radiation from the sky, the air temperature and the distance between the building and the camera.

Having said that, while the infra-red photographs cannot be relied on to give an exact temperature reading, they do give a pretty reliable indication of the relative temperatures of different surfaces (as long as the surfaces have similar roughnesses).

(4) The temperature of the roof of any given building depends on both (a) the temperature inside the building and (b) how well the roof is insulated.  If house A has a hotter roof than house B this could be because house B has better loft insulation than house A.  On the other hand, it could be because the occupants of house A have their thermostat turned up higher.
(5) A big 'thank you' to Lucite International for lending us the infra-red camera and to FLIR Systems for providing us with a copy of the software for analysing the images.

You can use this link to go to the Sadberge web site home page.