thermal comfort

Conditions of human thermal comfort was studied as function of the following parameters : dry bulb temperature (22.8 to 27.8 °C), relative humidity (20 to 65%), air velocity (0.15 and 0.25 m/s) and activity level (1 and 2.3 met) with a panel of 256 person

Suggests that particularly for outdoor thermal comfort assessments in cold conditions, non-steady state models should be applied. This and other new aspects are to be considered in a new internationally standardised Universal Thermal Climate Index (UTCI), at present being developed by the International Society of Biometeorology. Psychological factors also need to be considered, such as diverging thermal expectations indoors and outdoors. States that as a consequence, different approaches are needed to assess indoor or outdoor thermal comfort.

Describes the thermal model available, both simple and complex and outlines capabilities and limitations. States that all of the models have limitations for use in standards, including the accuracy of the physical simulation and the accuracy of the inputs to the model. States that the biggest limitation is probably the accuracy with which comfort perceptions can be related to the physiological variables simulated in the thermal models.

An analysis was done to look at the differences in the way occupants perceive the office environment. The surveys were done in an office with multinational workers in Japan. The 406 returned questionnaires were grouped by nationality and gender. 26% reported a comfortable working environment. There was a significant neutral temperature difference of 3.1 deg. C between the Japanese female group and the non-Japanese male group. Japanese females reported the highest frequency of sick building syndrome of any of the groups.

The paper compares a long and short term study of naturally ventilated buildings in a city in western Iran. For the hot season the neutral temperatures from the short and long term studies were 28.4 and 26.7 deg. C. For the cold season the short and long term neutral temperatures were 20.8 and 21.2 deg. C. Good agreement is shown between both studies. The results showed how acceptable conditions varied widely, a good relationship between neutral temperature and room temperature and between indoor comfort and outdoor conditions.

Summarises a study that found a clear impact of activity and overall thermal sensation on human sensitivity to air movement, while no interaction effects of exposure to several local thermal discomfort factors were observed. States that current standards tend to consider only sedentary light activity and a neutral thermal sensation.

Presents a series of laboratory studies into thermal comfort requirements. Groups of 16 persons were used in two studies, to look at the effects of gender over three-hour exposures in simulated living room and office environments. Only small differences were found in the thermal comfort response of male and female subjects in identical clothing conditions, for neutral and slightly warm environments. In cool conditions, females felt the cold more than males. Behavioural studies were conducted for persons maintaining thermal comfort by adjusting their clothing. A temperature of 18 deg.

Discusses, in the context of the Predicted Mean Vote (PMV) model, the representation and measurement of clothing parameters and metabolic rate. Identifies several problems and provides solutions to a few. Results showed the importance of the effects of body motion and air movement for clothing insulation, and suggests they should be incorporated into the model. The results also showed only small effect on dry heat exchange for stationary light work at low air movement. Suggests that algorithms for convective heat exchange in prediction models should be reconsidered.

Explains the origin and development of the adaptive approach to thermal comfort. Considers several recent developments in the application of the theory and the origin of the differences between adaptive thermal comfort and the 'rational' indices. Explores its application to comfort standards and makes recommendations about the best comfort temperature, the range of comfortable environments and the maximum rate of change of indoor temperature. Also mentions the application of criteria of sustainability to thermal standards for buildings.

Describes existing ISO standards and current projects concerning thermal comfort. Describes the production process for ISO standards. Considers the existing EN ISO 7730 thermal comfort standard in these terms and also ISO 8996 (metabolic rate0 and ISO 9920 (clothing). Also presents the work of ISO/TC 159 SC5, 'ergonomics of the physical environment'. Gives a detailed presentation of the proposed revision of EN ISO 7730. This will be based on requirements for general thermal comfort, operative temperature and local thermal discomfort.