No abstract

This review comprehensively examines scientific literature pertaining to human physiology during exercise, including mechanisms of heat formation and dissipation, heat stress on the body, the importance of skin temperature monitoring, the effects of clothing, and microclimatic measurements. This provides a critical foundation for microclimatologists and biometeorologists in the understanding of experiments involving human physiology. The importance of the psychological aspects of how an individual perceives an outdoor environment are also reviewed, emphasizing many factors that can indirectly affect thermal comfort (TC). Past and current efforts to develop accurate human comfort models are described, as well as how these models can be used to develop resilient and comfortable outdoor spaces for physical activity. Lack of suitable spaces plays a large role in the deterioration of human health due to physical inactivity, leading to higher rates of illness, heart disease, obesity and heat-related casualties. This trend will continue if urban designers do not make use of current knowledge of bioclimatic urban design, which must be synthesized with physiology, psychology and microclimatology. Increased research is required for furthering our knowledge on the outdoor human energy balance concept and bioclimatic design for health and well-being in urban areas.

This study assessed the performance of the COMFA outdoor thermal comfort model on subjects performing moderate to vigorous physical activity. Field tests were conducted on 27 subjects performing 30 min of steady-state activity (walking, running, and cycling) in an outdoor environment. The predicted COMFA budgets were compared to the actual thermal sensation (ATS) votes provided by participants during each 5-min interval. The results revealed a normal distribution in the subjects' ATS votes, with 82% of votes received in categories 0 (neutral) to +2 (warm). The ATS votes were significantly dependent upon sex, air temperature, short and long-wave radiation, wind speed, and metabolic activity rate. There was a significant positive correlation between the ATS and predicted budgets (Spearman's rho=0.574, P<0.01). However, the predicted budgets did not display a normal distribution, and the model produced erroneous estimates of the heat and moisture exchange between the human body and the ambient environment in 6% of the cases.

The purpose of this paper is to improve the accuracy of the COMFA outdoor thermal comfort model for application to subjects performing physical activity. A sensitivity analysis was performed to identify conditions where the COMFA model produced erroneous estimates of the heat and moisture exchanges between the human body and the ambient environment, based on data from subjects performing moderate-to-vigorous physical activity. Errors occurred at high metabolic rates (> 400 W m -2 ), high wind speeds (> 4 m s -1 ) and warm air temperatures (> 28°C).Revisions to the clothing resistance (r c ), clothing vapour resistance (r cυ ), skin tissue resistance (r t ), and skin temperature (T sk ) equations were proposed. The revised assessment revealed that subjects had a wide range of thermal acceptability (B=−20 W m -2 to +150 W m -2 ), which was offset to the warm-end of the comfort scale. The revised model (COMFA*) performed well, predicting the actual thermal sensation of subjects in approximately 70% of cases. This study effectively integrated current empirical research related the effect of wind and activity on the clothing microclimate to improve the application of an outdoor thermal comfort model for subjects performing physical activity.

The current study tests applications of the Comfort Formula (COMFA) energy budget model by assessing the moderating effects of urban parks in contrast to streets, and it also looks at the influence of park types (“open” or “treed”). Exploration into energy budget modeling is based on empirical meteorological data collected in Toronto, Ontario, Canada, on fair-weather days plus the effects of a heat wave and climate change, at various metabolic activity levels. Park cooling temperature intensities ranged from 3.9° to 6.0°C, yet human energy budgets were more closely correlated to incoming solar radiation than to air temperature. A strong linear dependence was found, with absorbed radiation (correlation coefficient squared r2 = 0.858) explaining the largest fraction of energy budget output. Hence, although the four parks that were examined are classified as urban green space, the distinctive treed areas showed a greater budget decrease than did open park areas (−25.5 W m−2). The greatest difference in budget decrease was found when modeling the highest metabolic rate, giving −20 W m−2 for “whole park,” −32 W m−2 for treed sections, and −3 W m−2 in open park areas. These results are intuitive within energy budget modeling and indicate that blocking radiant energy is a vital aspect in lowering high budgets under the conditions tested. Strong empirical support was provided through successful prediction of emergency-response calls during a heat wave in Toronto (5–7 July 2010) and surrounding days. Calls were found to be significantly dependent on the energy budget estimations (r2 = 0.860). There is great potential for outdoor energy budget modeling as a meaningful guide to heat stress forecasting, future research, and application in bioclimatic urban design for improving thermal comfort.