A well-designed ventilation system and proper insulation are needed to minimize stratification of air temperatures and maximize thermal comfort. If air is not properly mixed, there may be warmer air near the ceiling and cooler air by the floor. Ventilation diffusers should be spaced to provide even heating and cooling to the work areas. Large windows and poorly insulated walls and floors can lead to drafts in the winter and heat gain in summer. Recent evidence suggests that the perceived air quality is worse when temperatures rise above 76 F regardless of the actual air quality.
Humidity is also a factor.
Excessively high or low relative humidity can both produce discomfort. There is considerable debate concerning recommended levels of humidity. Elevated relative humidity reduces the body's ability to lose heat through perspiration and evaporation. When this happens, individuals may perceive temperatures to be higher than they actually are. High relative humidity may also promote the growth of mold and mildew.