Intrusive means of concrete investigation are seldom permitted on listed buildings. Locating faults which may have occurred by destructive means could result in much expense to the owner both financially and historically.
A grade II listed building in Westminster was one of the first to have an upgraded thermogrphy test, carried out by consultant Aperio.
The building was typical of many Victorian premises which contain redundant internal flues no longer of use. Thermography was used to locate the flues so that engineers could remove them and re-use the vacant space.
The camera picked out the warmth of the vertical flues as internal heat escaped more easily in these areas than through denser concrete or brickwork. Sections of the face were observed with single infrared images. The lighter colouring of the pipes showed a 0.5C ambient temperature change from most of the structure's elevation, giving the engineers behind the lens a clear idea as to where the features covered by concrete were located.
Director of AperioSimon Brightwell said: 'We used the sid e elevation to check for hidden structures within the walls. It is a typical test where ducts and vents can be identified and re-used.'