Civil Engineering Reference
In-Depth Information
Temperature and Humidity
The first step toward maintaining acceptable IAQ is to control tem-
perature and humidity to acceptable levels in each occupied space; if
building occupants are too hot or too cold, they are “uncomfortable” and
may become more sensitive to indoor air quality. Therefore, it is impor-
tant that indoor temperatures be maintained with a comfort range. Based
on ASHRAE, building HVAC controls should be set to maintain indoor
temperature conditions at 75°F ± 2°F.
Humidity also has direct effect on the indoor human health param-
eters, as shown in the Figure 4-2.
Thus, while most people are “comfortable” with humidity as low
as 20-30% RH, the optimum low limit on humidity is 40% RH, though
a 30% RH is acceptable unless maintained for long periods (northern
climates).
Lighting
Poor lighting can be an irritant that exacerbates other IAQ problems
and can produce its own health risk in the form of headaches and eye
Figure 4-2. Health Effects vs. Relative Humidity (Adapted from ASHRAE
Transactions, 1984)
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