Figure 27.7 A: Temperature in degrees Fahrenheit; B: Maximum amount of water in gr/ft
3
(at sea level)
BABABABA
2.1232.04.1250.07.5868.013.3086.0
1.9630.23.8648.27.1466.212.6084.2
1.8128.43.6246.46.7364.411.9382.4
1.6726.63.4044.66.3462.611.2980.6
1.5424.83.1842.85.9760.810.6878.8
1.4223.0.2.9841.05.6259.010.1077.0
1.3121.22.7939.25.2957.29.5475.2
1.2119.42.6137.44.9755.49.0173.4
1.1117.62.4435.64.6753.68.5171.6
1.0215.82.2833.84.3951.88.0369.8
Example:
The relative humidity of a certain volume of air at a temperature of +30°C (+86°F) is
40 % RH. Amount of water in 1 m
3
(35.31 ft
3
) of air at +30°C = 30.44 × Rel Humidity
= 30.44 × 0.40 = 12.18 g (187.96 gr).
27.3.7.2 Definition of dew point
Dew point is the temperature at which the humidity in a certain volume of air will
condense as liquid water.
Example:
The relative humidity of a certain volume of air at a temperature of +30°C (+86°F) is
40 % RH. Amount of water in 1 m
3
(35.31 ft
3
) of air at +30°C = 30.44 × Rel Humidity
= 30.44 × 0.40 = 12.18 g (187.96 gr). In the table above, look up the temperature
for which the amount of water in air is closest to 12.18 g. This would be +14.0°C
(+57.2°F), which is the approximate dew point.
27.3.8 Excerpt from Technical Note ‘Assessing thermal bridging and
insulation continuity’ (UK example)
27.3.8.1 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).
168 Publ. No. 1558792 Rev. a460 – ENGLISH (EN) – July 1, 2010
27 – Introduction to building thermography
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