14
Control of Thermal Comfort
The thermal comfort of the occupants of a building depends on many factors including metabolic rates, clothing, air temperature, mean radiant temperature and air velocity and humidity (Tse and So, 2000; Mirinejad et al., 2008). In most buildings, however, only temperature and humidity can be controlled (Schumacher et al., 1998). Indeed, in many European buildings, over a wide range of humidity, only zone temperature is controlled (Kummert et al., 1997). In such cases, the control objective is then to maintain the zone temperature within a pre-defined range (Lute and van Paassen, 1995; Hagras et al., 2008).
The predicted mean vote (PMV) is often used as an overall index of the global thermal comfort conditions (Calvino et al., 2004, 2010). PMV refers to “the mean value of the votes of a large group of persons on a 7-point thermal sensation scale (see Table 14.1) based on the heat balance of the human body” (Fanger, 1972). PMV depends on an individual's metabolic rate and the thermal resistance of his/her clothing as well as the air temperature, the mean radiant temperature, the air velocity and the relative humidity of the air. A neutral thermal balance is achieved when the internal heat production in the body is equal to the loss of heat to the environment. Neutrality of thermal sensation, which can be assumed to correspond to the desired thermal comfort condition, is given by a PMV of zero with a tolerance of .
Predicted percentage of dissatisfied ...
