 |
Get an indication of how good your roof insulation is. |
Contact information
Environmental Assessment Manager
Luton Borough Council, Town
Hall
George Street
Luton, Bedfordshire
LU1 2BQ
tel: 01582 54 61
76
fax: 01582 54 68 51
To help to see which buildings in Luton have high heat losses through their roofs an Aerial Thermal Survey was done in the early hours of Wednesday January 30th by Blue Sky International for Luton Borough Council.
A special digital camera was used that is sensitive to the different levels of infra-red light that is given off by objects. Different temperatures give off different frequencies of Infra-red light, the frequencies are converted to 255 different shades from black through to white. The digital images were taken as strips when the plane flew over Luton, Blue Sky then joined the strips together and manipulated them to coincide with an Ordnance Survey Master Map file of Luton buildings.
The data file was then sent on a CD to Luton Borough Council’s Information Management Service where the aerial thermal data that did not lay over building polygons was discarded. The thermal data overlying a single building polygon has varying values from 0 – 255, as there will be variations in the temperature - for example if there is a flue coming through the roof.
The average pixel value for each polygon was therefore automatically calculated to represent the average temperature of each building roof. The pixel values for each roof were then sorted into 9 classes, with an equal number of buildings in each class. The hottest heat class was designated as being red and the coldest heat class as blue, with intermediate classes being given colours of red through blue.
It should be noted that the heat value colours do not represent absolute temperatures; they are only intended to show the relative temperatures, at the time of the survey, of the building roofs.
The roof colour is an indication of how good the insulation is in the roof, assuming that the building is being heated.
HIGH
LOW Aerial Thermal
mapping
heat loss
WARNING
There will be false negatives, that is, buildings
showing blue or (colder) colours suggesting good levels of insulation, when in
fact the insulation is not good. This is most likely to occur where a building
is unoccupied or the occupiers are on holiday and there is no heating on. There
may also be false positives, where, for example, a loft hatch has been left off
and hot air has got into the roof void and warmed it up.
Interpreting the maps
Looking at the colour of your roof, compare it to the colour of neighbours’ roofs in your street and nearby streets. The nearer you roof is to the blue end of the row of colours the better your insulation (subject to the above warning). The nearer your roof is to the red end of the row of colours the worse your insulation (subject to the warning above).
What do I need to do if it seems like my insulation isn’t very good
If you are able to, you could look in your loft space and see how much insulation there is between the rafters. Recommended insulation standards and insulation thicknesses have increased in recent years and insulation tends to compact with time and become less effective. Loft insulation of up to 300 mm/12 inches is now recommended, though this amount may not always be practical.
As well as how good the insulation is in your roof you should also consider how well insulated your walls and windows are. For advice on all home insulation, phone the Council’s Partner Cocoon Your Home on 0800 8048777 or www.cocoonyourhome.co.uk
