Dear MEL Topic Readers,
This paint could cool your home and harvest water from the air
Cities are becoming hotter and hotter as concrete and rooftops absorb
the sun’s energy, causing the urban heat island effect. If the sun’s energy is
reflected, urban temperatures might be reduced during the summer. Do paints
help increase the reflection of the sun’s energy? Total Solar Reflectance (TSR)
measures how much sunlight a paint reflects. For example, black paint typically
reflects less than 10% of sunlight, or absorbs 90% or more of the sun’s energy,
while white paint reflects around 70% to 80% of incoming sunlight. Naturally, a
white-painted building is cooler than a black-painted one under the sizzling
summer sun. Now, an Australian startup has developed a special coating that
reflects up to 96% of incoming sunlight, which keeps the roof surfaces as much
as 6 degrees Celsius cooler than the surrounding air. If more rooftops are painted
with this nanoengineered special coating, the urban heat island effect will be
eased without costing any environmental burden. Also, if the surface
temperature is lower than the surrounding temperature, moisture in the air is
condensed on the surface, like water is formed on the outside of a cold glass. Once
the water is collected, it can be used as a supplemental water source for the toilet
or shower. Passive radiative cooling, a technology that cools surfaces by reflecting
sunlight and radiating trapped heat outward into the cold sink of deep space, is
expected to play a vital role in cooling cities while reducing carbon emissions.
Read the article and learn how city temperatures can be cooled without
running air conditioning.
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