Comfort Temperature of Iranian People in City of Tehran



From building design point of view a basic aim of low energy architecture is to create a thermally comfortable internal environment for building occupants whilst consuming the least possible amount of energy. Thus, thermal comfort study has an important impact on energy saving. Achieving comfort conditions requires an understanding of the interaction between three groups of factors, namely physiological and psychological parameters joint with behavior of occupants, design of the building and the outdoor environment. The definition of thermal comfort for a person, in agreement with ASHRAE standard 55 [1992] is “that condition of mind which expresses satisfaction with the thermal environment”. By and large, it is known that there are heat transfers between human body and its environment, and a thermal balance between the two, which is simplified as the condition of thermal comfort. There are, also, two main methods of determining thermal comfort i.e. through climate chamber experiments or through field studies. Climate chamber experiments are performed in laboratory conditions, while field studies are carried out anywhere as long as the right instruments are available. The comfort temperatures determined from various studies in real world vary notably from one to another and are sometimes difficult to reconcile with the temperatures calculated from the climatic chamber experiments. Concern of these phenomena led to viewing thermal comfort as part of a self- regulating system which has become generally known as the adaptive model. This model has been supported by many studies in thermal comfort. The adaptive model recognizes that a person is not a passive receiver of sense impressions but is an active participant in dynamic equilibrium with the thermal environment. In fact comfort and discomfort are dynamic in character and it is, therefore, unlikely that a comfort zone can be adequately described by means of temperature intervals alone; the time-dimension will also need to be incorporated into its definition. This paper investigated thermal comfort for naturally ventilated buildings in Iran with special reference to Tehran. An important aim was to establish the neutral temperature and the acceptable range of environmental conditions for people in their buildings. The methodology used for this aim was field studies. These studies were divided into two parts- one in the hot season and the other in the cool season. The results showed a good relationship between neutral temperature and mean outdoor temperature. The indoor comfort temperature (Tn), which is dependent on outdoor temperature (To), could be found from this equation: (Tn = 12.8 + 0.555 To). The findings of the study revealed that the people could achieve comfort at higher indoor air temperatures compared with the recommendations by international standards like ISO 7730. The results also, showed the strong relationship between prevailing temperatures and neutral temperature which is in good agreement with adaptive model. The results suggested that an appropriate passive strategy for building design can be enough for desirable indoor condition in Tehran. It cannot be questioned that thermal comfort has been recognised by people in different ways according to different insights and different expectations of life.