Humidity & Dew Point; Relative & Absolute Humidity; Definition Of Dew Point; Excerpt From Technical Note 'Assessing Thermal Bridging And Insulation Continuity' (Uk Example) - FLIR i3 User Manual

Deviations and irregularities in the appearance of the infrared image often indicate
insulation defects. There may obviously be considerable variations in the appearance
of infrared images of structures with insulation defects. Certain types of insulation
defects have a characteristic shape on the infrared image.
Section 16.3 – Typical field investigations on page 49 shows examples of interpreta-
tions of infrared images.
When taking infrared images of the same building, the infrared images from different
areas should be taken with the same settings on the infrared camera, as this makes
comparison of the various surface areas easier.
16.4.7 Humidity & dew point
16.4.7.1 Relative & absolute humidity
Humidity can be expressed in two different ways—either as relative humidity or as
absolute humidity. Relative humidity is expressed in percent of how much water a
certain volume of air can hold at a certain temperature, while absolute humidity is
expressed in percent water by weight of material. The latter way to express humidity
is common when measuring humidity in wood and other building materials.
The higher the temperature of air, the larger the amount of water this certain volume
of air can hold.
16.4.7.2

Definition of dew point

Dew point is the temperature at which the humidity in a certain volume of air will
condense as liquid water.
16.4.8 Excerpt from Technical Note 'Assessing thermal bridging and
insulation continuity' (UK example)
16.4.8.1

Credits

This Technical Note was produced by a working group including expert thermogra-
phers, and research consultants. Additional consultation with other persons and or-
ganisations results in this document being widely accepted by all sides of industries.
The contents of this Technical Note is reproduced with kind permission from, and
fully copyrighted to, United Kingdom Thermography Association (UKTA).
UK Thermography Association
c/o British Institute of Nondestructive Testing
1 Spencer Parade
Northampton NN1 5AA
United Kingdom
Tel: +44 (0)1604 630124
Publ. No. T559580 Rev. a486 – ENGLISH (EN) – November 17, 2010
16 – Introduction to building thermography
83