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Green Spaces Linked to Increased Thermal Comfort
Reduce Physiological Equivalent Temperature


A study from Universidad Politécnica de Madrid has quantified how much green spaces can reduce the urban heat island effect. On average, green spaces decrease the physiological equivalent temperature, or the air temperature at which body heat is balanced with the surrounding temperature, by around 2 ?C.

New research from Universidad Politécnica de Madrid, or Madrid Polytechnic University in Spain, confirms that an increase in green spaces in cities can moderate the urban heat island effect and as such increase the thermal comfort of citizens.

Thermal comfort is defined as "the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation," according to ANSI/ASHRAE Standard 55. In other words, it is when an individual is at a comfortable temperature, not too hot and not too cold. Air temperature is the most common factor to indicate thermal comfort, though radiant temperature, air velocity, humidity, clothing insulation and metabolic heat all play a part as well.

By simulating different scenarios of green areas, members of the research group Bioclimatic Architecture in a Sustainable Environment assessed the thermal comfort modification potential of an urban park in Beijing, and established the differences among the physiological equivalent temperature on each situation. Scenarios included areas of grass, 32' trees, 65' trees, hardened ground, water bodies, and buildings.

The taller trees were found to have the greatest influence on thermal comfort, while hardened ground was the worst.

Esther Higueras, lead researcher on the project, suggested that the results of the study will "allow us to make suggestions to designers of urban parks such as to increase the coverage of taller trees, implement effective approaches in uncovered spaces, reduce the percentage of hardened pavement, or to display the landscape parameters, taking into account aesthetic aspects that can influence the perceived thermal sensation."

The full report is available at

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August 20, 2019, 10:10 am PDT

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