Predicted Mean Vote PMV and PPD Thermal Comfort Model
topic
The predicted mean vote model calculates the expected mean thermal sensation rating of a large group of people on a seven-point scale from cold to hot as a function of six parameters — air temperature, mean radiant temperature, relative humidity, air velocity, metabolic rate, and clothing insulation — using heat balance equations that describe the conditions under which the average person is thermally neutral. The predicted percentage dissatisfied index derived from the predicted mean vote quantifies the fraction of people expected to be uncomfortable at any given thermal condition, providing a design criterion for building thermal environments. The model's adoption in ISO 7730 and ASHRAE 55 as the primary analytical method for thermal environment assessment makes clothing insulation input a critical link between textile performance measurement and built environment comfort engineering.
Role
The predicted mean vote model is the universally adopted analytical framework for thermal comfort in building design and occupational health — making clothing insulation the direct input variable that connects textile thermal resistance measurement to the comfort engineering of office environments, public spaces, and industrial workplaces where thermal environment specification must account for the wide range of clothing worn by occupants across seasons and personal preference.