| People "feel comfortable" over a wide range of temperatures
and conditions, depending upon age, weight, sex, and level of physical
activity. A sedentary person could feel "cold" at 74°F if the humidity is
low, while a factory worker could feel warm at 65°F if they are performing
heavy manual labor. The HVAC system designer usually has to make a
compromise, and most design to accepted criteria for human comfort. During
the summer, interior office space is usually designed to hold a maximum
temperature of 75°F and a relative humidity of 50%. But, some areas of the
country have very low humidity, even during these summer months. This means
the space temperature could be set at 78-80°F and provide the same level of
comfort.
The comfort levels are also dependent upon air movement. Someone sitting
in a space with inadequate air movement is likely to feel "closed in." A
certain amount of fresh air must be introduced. This is defined by ASHRAE
standards for the building type and intended use.
ASHRAE standards provide CFM/person and CFM/sq.ft. guidelines..
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