Cooling Comfort

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.