Page 1 (0s)
[Virtual Presenter] The main difference between both TCMs, steady and adaptive, lies in the importance attached to each factor or group of factors. The steady model, developed by Fanger [6] in 1970, was based on empirical research on skin temperature carried out in the static conditions of climate-controlled chambers. Fanger developed a mathematical equation describing the heat transfer between the human body and the indoor environment. The sensation of thermal comfort occurs when the internal heat production of the body is equal to its loss from the environment..
Page 2 (41s)
[Audio] The Predicted Mean Vote (PMV) index predicts the mean comfort vote of a group of people on a seven-point scale (from −3 to 3) based on the values of four physical indoor parameters (air speed, air temperature, humidity and mean radiant temperature), one physiological parameter (metabolic rate), and a behavioural one (clothing insulation). Neutral indoor temperature is that at which PMV equals zero. A thermally comfortable environment is that in which PMV ranges between −1 and 1.
Page 3 (1m 18s)
[Audio] The adaptive approach was further developed by Brager & de Dear [5,8] and Nicol & Humphreys [9] between 1998 and 2002. This approach is based on the hypothesis that "contextual factors and past thermal history modify building occupants' thermal expectations and preferences." The main difference from the steady model is that the greatest weight is attached to external temperature, which people are able to adapt to and is not considered in Fanger's equation. With this theory, which arose from the analysis of 21,000 data series collected in 160 buildings from four continents, Brager & de Dear confirmed that individuals displayed higher levels of tolerance in naturally ventilated buildings to a wider range of indoor temperatures than that predicted by the steady model. According to the authors this was the result of a combined behavioural and physiological adjustment and psychological adaptation, captured in a linear equation establishing a correlation between the most recent climate conditions and the optimal comfort temperature inside the buildings..