Environmental factors include air temperature, humidity, wind, air speed and radiation from surfaces, while personal factors take into account what a person is wearing and what activity he or she is involved in.
Ms Kuo said thermal comfort was best represented by an internationally-recognised metric called the physiological equivalent temperature (PET), which essentially refers to the “feels like” temperature.
In Sentosa, the consultancy used on-the-ground field measurements during peak afternoon hours and computational modelling to establish a heat map of Sentosa, showing its outdoor thermal comfort baseline.
The study then identified locations where interventions were needed to improve the effects of heat.
The results were a range of PETs at outdoor spots across the island.
More than half of the 500ha island is currently covered with greenery, and areas close to these, such as Mount Imbiah and Mount Serapong, saw considerably cooler PETs of 34 degrees Celsius and 33 degrees Celsius respectively.
Meanwhile, Palawan Beach had a PET of 49 degrees Celsius. The highest PET – 56 degrees Celsius – was measured at Resorts World Sentosa (RWS) Plaza.
In the areas with high PETs, Ms Kuo said solar radiation and the built environment could be factors.
“So, for example, in the city … We have a lot of hard surfaces, a lot of towers around you, all those buildings, materials, they absorb the heat, so they are constantly also radiating heat out into the environment.
“So the PET levels between a very open space … like (in) a car park, for example, versus a place where you’re surrounded by buildings, you might feel slightly cooler (in) a car park, whereas if you’re surrounded by buildings, you might feel a little bit more stuffy and … hotter.”
Singapore Management University’s Professor of Urban Climate Winston Chow said the humid ambient environment, high sun exposure in the afternoons, and low wind speeds were three key factors contributing to the PET.
“However, the bigger challenge is that PET tolerance also depends on how acclimatised people are in the location,” Prof Chow added, referring to tourists.
“Given that a significant proportion of Sentosa’s visitors come from climates that differ from Singapore, it is likely that creating a cooler-than-expected environment is needed to ensure that visitors used to a temperate climate will not be subject to heat stress that Singapore residents may be acclimatised to.”
