PMV index predicts the mean comfort response of a larger group of people
The PMV index predicts the mean response of a larger group of people according the ASHRAE thermal sense scale:
+1 slightly warm
-1 slightly cool
The PMV index is expressed by P.O. Fanger as
PMV = (0.303 e-0.036M + 0.028) L (1)
PMV = Predicted Mean Vote Index
M = metabolic rate
L = thermal load - defined as the difference between the internal heat production and the heat loss to the actual environment - for a person at comfort skin temperature and evaporative heat loss by sweating at the actual activity level
PPD - Predicted Percentage Dissatisfied Index
Predicted Percentage Dissatisfied - PPD - index is a quantitative measure of the thermal comfort of a group of people at a particular thermal environment.
Note! - at least aprox. 5% of people in a group will be dissatisfied with the thermal climate - even with PMV = 0.