Clothing insulation is the thermal resistance of garments worn by occupants, measured in units called clo, where 1 clo equals 0.155 m²K/W (0.88°F·ft²·h/Btu). It directly affects how readily the body exchanges heat with the environment and is a primary variable in thermal comfort calculations. Clothing insulation values range from 0.3 clo for light summer clothing to 2.0 clo for heavy winter layers.
Technical Details
ASHRAE Standard 55 defines clothing insulation for standard ensembles: underwear plus shirt plus trousers equals 0.6 clo; adding a light jacket brings insulation to 1.0 clo. Dynamic clothing insulation accounts for air permeability and movement effects. Individual variations in fit and layering can shift insulation values by ±0.2 clo. Thermal comfort models require accurate clothing insulation input to predict occupant satisfaction correctly.
Applications in HVAC Design
Comfort zones adjust operative temperature based on expected seasonal clothing. Winter settings account for heavier garments; summer settings assume lighter dress. Dress codes in commercial buildings influence HVAC setpoint strategies.
Practical Significance
Recognizing clothing insulation variations helps HVAC designers establish appropriate temperature ranges without compromising comfort or excessive energy use.