INGENIEUR
Figure 2: Latent Load Characteristics
‟
Comparing the
sources of the latent
load, it is clear that the
largest contribution to
the latent component
is outside air.
6
34
VOL
2019
VOL 77
55 JANUARY–MARCH
JUNE 2013
Medium sized retail store in : Atlanta
During : 0.4% dewpoint conditions
Source : Lewis Harriman
Latent Loads
If RH control is so critical and important, we
should examine the latent load profiles in a
building. Comparing the sources of the latent
load, it is clear that the largest contribution to the
latent component is outside air. The chart (Figure
2) clearly shows that the almost 50% - 70% of
internal latent load comes from ventilation.
RH Control Challenge
Why is it so difficult to manage RH? The answer
lies in the fact that the sensible and latent loads
don’t peak at the same time.
Hence in moderate weather the sensible loads
are reduced but the latent load remains high.
Experiencing moderate weather over a
considerable part of the year in many ASEAN
cities, this problem needs some immediate
attention. Consider the grains levels in outside
temperatures of 75ºF (i.e. moderate weather), one
can see a considerable number of hours where
the grains level is more than 65 grs/lb (moisture
level generally maintained inside).