Thermal bioclimatic conditions and patterns of behaviour in an urban park in G�teborg, Sweden

Abstract

People in urban areas frequently use parks for recreation and outdoor activities. Owing to the complexity of the outdoor environment, there have only been a few attempts to understand the effect of the thermal environment on people's use of outdoor spaces. This paper therefore seeks to determine the relationship between the thermal environment, park use and behavioural patterns in an urban area of Sweden. The methods used include structured interviews, unobtrusive observations of the naturally occurring behaviour and simultaneous measurements of thermal comfort variables, i.e., air temperature, air humidity, wind speed and global radiation. The thermal environment is investigated through the mean radiant temperature (Tmrt) and the predicted mean vote (PMV) index. The outcome is compared to the subjective behaviour and thermal sensation of the interviewees. It is found that the thermal environment, access and design are important factors in the use of the park. In order to continue to use the park when the thermal conditions become too cold or too hot for comfort, people improve their comfort conditions by modifying their clothing and by choosing the most supportive thermal opportunities available within the place. The study also shows that psychological aspects such as time of exposure, expectations, experience and perceived control may influence the subjective assessment. Comparison between the thermal sensation of the interviewees and the thermal sensation assessed by the PMV index indicates that steady-state models such as the PMV index may not be appropriate for the assessment of short-term outdoor thermal comfort, mainly because they are unable to analyse transient exposure.

Evaluation of Different Urban Microclimate Mitigation Strategies through a PMV Analysis

“…Differently, the results of a study conducted by Cheng et al [62] in Hong Kong show that PMV generally overestimates the thermal sensation towards the warmer end of the scale in summer and vice versa in winter. Thorsson et al [63] reached similar conclusions in the city of Göteborg (Sweden): they compared thermal sensations assessed by the PMV and thermal sensations obtained through interviews finding that the PMV curve was skewed towards the warm zone. Another study was carried by Mahmoud [64] in Egypt and it examined nine zones representing various spaces inside an urban park located in Cairo: even if this study used the PET (Physiological Equivalent Temperature) [65], the authors highlighted how, for one of these zones, the calculated PMV was not significantly different from the mean thermal sensation vote obtained from subjective questionnaires.…”

Green-Roof Effects on Neighborhood Microclimate and Human Thermal Sensation

“…In vegetated areas with suppressed ground-level radiation input, lower air temperature and elevated relative humidity than their surrounding built-up spaces, improvement of HTC could be expected. Some studies have confirmed notable enhancement of HTC by urban parks or tree groups [28,29], whereas little research has incorporated HTC in the assessment of green roof benefits.…”

Estimating the radiation absorbed by a human

“…Originally developed for application in indoor environments, T mrt is described as the uniform temperature of a hypothetical enclosure that would result in the same radiant heat transfer with the subject as in the actual complex environment (Fanger 1972;Matzarakis et al 2007). T mrt is frequently modeled using a globe thermometer (Nikolopoulou and Lykoudis 2006;Thorsson et al 2004;Nikolopoulou et al 2001;Schiller 2001). Based upon the equilibrium temperature of the globe and an energy balance approach to modeling the radiative and convective heat fluxes from the sensor, T mrt is calculated based upon the globe temperature, air temperature and air velocity (Thorsson et al 2007;Fanger 1972).…”