ENGINEERING INSIGHTS | What If a Building Could Cool Itself Before the Air Conditioning Even Starts?
In the Sahara, one of the most effective cooling systems belongs to an ant.
The Saharan silver ant, Cataglyphis bombycina, survives in an environment where ground temperatures can become extreme.
Its silver appearance is not simply colour.
Under a microscope, much of the ant's body is covered in dense, triangular hairs. Research has shown that these structures help manage heat in two ways: they reflect incoming solar radiation and improve the body's ability to release thermal radiation.
It is a remarkably effective piece of natural thermal engineering.
And researchers have been studying how to recreate it.
By mimicking aspects of these microscopic structures, researchers have developed materials for passive radiative cooling. Rather than removing heat after a building becomes warm, these materials aim to reduce solar heat gain while allowing thermal energy to radiate away.
One bio inspired polymer surface tested in Hong Kong demonstrated temperatures up to 6.2°C below ambient under the study conditions.
The idea is now being tested at building scale.
A study on an operating office building in Hong Kong recorded a maximum 21.1°C reduction in external roof surface temperature and a 20% reduction in cooling electricity during the monitored comparison.
A 2026 full scale building experiment also recorded lower surface and indoor temperatures, with a 21% reduction in cooling demand during the September test period.
That does not mean buildings are about to stop needing mechanical cooling.
Climate, humidity, orientation, surrounding surfaces, material durability and building design all influence performance. These technologies are being explored as part of a wider building cooling strategy, rather than a universal replacement for air conditioning.
And that is where it becomes particularly interesting for building services engineering.
Every watt of heat prevented from entering a building is heat the mechanical system may not have to remove later. Lower heat gain can mean lower cooling demand, reduced peak loads and less pressure on mechanical plant and electricity infrastructure. Sometimes improving the way we cool buildings does not begin with a bigger cooling system. It begins with reducing the cooling the building needs in the first place.
And in this case, part of the idea came from an ant surviving under the Saharan sun.
Image Credits: Bjørn Christian Tørrissen, Wikimedia Commons, CC BY SA 3.0 | Norman Nan Shi and Nanfang Yu, Columbia Engineering | Solar Energy Materials and Solar Cells
Research: Shi et al., Science | Jeong et al., Solar Energy Materials and Solar Cells | Building scale studies, 2025 and 2026
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