Imagine summer days without the constant hum of air-conditioning. Researchers in Singapore have taken inspiration from sweating skin to create a cement-based paint that can passively cool buildings, even in steamy, humid climates. By reflecting sunlight, emitting heat, and slowly releasing stored water, this innovative coating offers a multi-layered defence against rising indoor temperatures. As reported in Science News, a pilot study across three test homes showed that this new “sweating paint” reduced cooling energy use by 30–40% over two years, while retaining its bright white colour where other test paints yellowed or dulled.
Cooling by design: how the paint works
Conventional cooling paints typically work through radiative cooling, reflecting sunlight and emitting absorbed heat into the atmosphere. However, in hot and humid places like Singapore, high moisture levels in the air can limit how much heat escapes. To counter this, researchers added an evaporative element to their design.
The paint has a porous structure that absorbs rainwater, which is then released as vapour when temperatures rise. This mimics the way human skin cools down through sweating. The formulation reflects 88–92% of sunlight and emits up to 95% of heat, even in damp conditions. It contains nanoparticles to protect the colour and polymers and salts to store and regulate moisture without damaging the walls. In testing, the paint was compared against a standard white emulsion and a commercial cooling paint. Only the sweating paint remained pristine after two years in full exposure, and it also resulted in the lowest demand for air conditioning, pointing to its potential to reshape sustainable housing design. This triple-effect combination of reflection, radiation, and evaporation marks a notable step forward in passive cooling tech.
Could this work in the UK?
The potential for this type of cooling paint in the UK is intriguing. Although our climate isn’t tropical, prolonged summer heatwaves are becoming more common. Many UK homes, particularly older ones, aren’t designed to stay cool, and air conditioning remains rare. Passive cooling methods like this could offer a low-energy solution to keep homes bearable during hot spells.
Retrofitting could be particularly impactful. Applying breathable, moisture-regulating coatings to exterior walls or roofs of Victorian and Edwardian homes might help cut internal heat levels without disrupting historic features. For new builds, this kind of paint could be standard, especially in urban areas dealing with the urban heat island effect.
Of course, it would need to be adapted to local conditions. UK rain patterns, temperatures, and housing materials differ from Singapore’s. There would also need to be rigorous testing to ensure that the paint doesn’t trap too much moisture, which could lead to mould or damp problems. The research team behind the paint has accounted for this with a carefully balanced formula, but further trials will be key before it sees wider use in temperate zones.
Cities around the world are already experimenting with reflective surfaces to mitigate urban heating. A recent Guardian article noted the growing interest in AI-driven materials research, including efforts to find optimal paint formulas. This Singaporean team may have landed on one of the most promising designs yet.
What’s next for the sweating paint?
For all its promise, the paint is still in its early days. More testing is needed across a variety of climates, home sizes, and surfaces to ensure long-term durability and consistent performance. Questions also remain about its cost, ease of application, and commercial scalability.
Still, the potential benefits are enormous. Passive cooling paints could dramatically reduce global demand for air conditioning, particularly in regions where electricity costs are high or grids are under stress. They could also make a difference in public housing, schools, and hospitals—spaces where thermal comfort is vital, but budgets are limited.
What’s exciting is the simplicity of the idea: mimic nature, use available materials, and reduce energy use without needing expensive upgrades or tech-heavy systems. If the next phase of development proves successful, we could see sweating paint rolled out in a range of climates, from equatorial cities to increasingly hot northern regions like ours.
As the UK continues to adapt to a warming climate, solutions like this may prove not just innovative, but necessary. Urban planners, developers, and homeowners should be paying close attention. A lick of the right paint, it seems, might cool more than just walls. It could cool entire communities.