FLIR BCam User Manual

■ The surface temperatures used are the averages of surface temperatures on the
same material in an area near the anomaly on the inside and the outside of the
fabric. Together with the temperature of the anomaly, a threshold level can be set
dependent on these temperatures using the critical surface temperature factor.
■ These arguments do not obviate the need for the thermographer to beware of re-
flections of objects at unusual temperatures in the background facing the building
fabric surfaces.
■ The thermographer should also use a comparison between external faces facing
different directions to determine whether there is residual heat from solar gain af-
fecting the external surfaces.
■ External surveys should not be conducted on a surface where T
si
– T
so
on the face
is more than 10% greater than T
si
– T
so
on the north or nearest to north face.
■ For a defect that causes a failure under the 0.75 condition of IP17/01 the critical
surface factors are 0.78 on the inside surface and 0.93 on the outside surface.
The table below shows the internal and external surface temperatures at an anomaly
which would lead to failure under IP17/01. It also shows the deterioration in thermal
insulation that is necessary to cause this.
Failing areaGood areaExample for lightweight built-up cladding with defective
insulation
00Outside temperature in ℃
0.750.95Surface factor from IP17/01
1.50.3Outside surface temperature in ℃
0.92Critical external surface temperature factor, after IP17/01
5.180Insulation thickness to give this level of performance, mm
1.920.35Local U value W/m
2
K
15.019.1Inside surface temperature in ℃
0.78UKTA TN1 surface factor
0.93UKTA TN1 surface factor outside
Notes to the table
1 Values of surface resistances taken from ADL2 2001, are:
■ Inside surface 0.13 m
2
K/W
■ Outside surface 0.04 m
2
K/W
These originate from BS EN ISO 6946 (BN EN ISO 6946:1997 Building components
and building elements - Thermal resistance and thermal transmittance - Calculation
method).
12
110 Publ. No. 1558299 Rev. a200 – ENGLISH (EN) – February 12, 2007
12 – Introduction to building thermography

FLIR BCam Specifications

General

Brand	FLIR
Model	BCam
Category	Thermal cameras
Language	English