A real-world study by researchers at NTU Singapore has revealed that the application of cool paint coatings in cities can help pedestrians feel up to
1.5 degrees Celsius cooler, making the urban area more comfortable for work and leisure.
Cool paint coatings contain additives that reflect the sun's heat to reduce surface heat absorption and emission. They have been regarded as a potential solution to cool down the urban area and combat the Urban Heat Island effect, a phenomenon in which urban areas experience warmer temperatures than their outlying surroundings.
Now, NTU researchers have conducted a pioneering real-world study to comprehensively evaluate how well cool paint coatings work in reducing city heat.
To carry out their real-world experiments, the NTU researchers selected four rectangular buildings that created two "street canyons"—narrow streets lined by buildings. One canyon, or "cool canyon" was coated with cool paints on the roofs, walls, and road pavement, while the other canyon remained as it was as a "control" for the experiment. Using environmental sensors, the NTU team monitored the conditions in the two canyons over two months, which included air movement, surface and air temperature, humidity, and radiation, to see how well the cool paint coatings worked in reducing city heat.
The researchers found that during a 24-hour cycle, the cool canyon saw up to a 30%reduction in heat released from the built-up surfaces, resulting in the air temperature in the cool canyon being cooler than the conventional canyon by up to 2℃ during the hottest time of the day, at around 4 pm. As a result, pedestrians in the cool canyon can feel up to
1.5℃ cooler. The NTU research team also found that air temperature in the cool canyon was lowered because less heat was absorbed by and stored in the building walls, roofs, and roads, which would subsequently have been released to either heat up the surrounding air or the building's inside.
With global warming, people will increasingly look for ways to stay cool. The study shows how cool paint coatings can be a strategy to reduce the Urban Heat Island effect in future.