Urban Heat Island

infra red Hong Kong Island by John A. Herbert

Here is an interesting image, the infrared of Hong Kong Island promenade, the sum has been shining all day and the path is absorbing the sun’s energy, the walkway is warmer than its surroundings. At night, that stored energy keeps the area warm, warmer than the air temperature, a good example of the urban heat island effect.

Infra-red is accurate and very sensitive, the image even shows the edges of the manhole covers!

It is not too difficult to avoid this problem (remember white reflective roof post) choose a material with a high solar reflectance index (SRI) say 80 or above, that will reduce the energy absorbed.