A new passive cooling paint reduces indoor temperatures without the need for electricity and captures moisture from the air to produce potable water, offering a low-cost solution for addressing heat and water stress.

As global temperatures rise and water scarcity intensifies, simple innovations can make a big difference. The passive cooling paint is one such breakthrough, lowering indoor temperatures without the need for electricity while capturing moisture from the air to produce potable water. Lightweight, low-cost, and low-maintenance, the technology could benefit homes, schools, shelters, and other community buildings. Recent research published in Advanced Functional Materials confirms that new formulations of the paint use radiative cooling principles to reject heat into outer space, enabling temperature drops even under direct sunlight.

The paint works in two ways. First, it reflects sunlight and radiates heat away from surfaces, keeping rooftops and walls cooler. Tests show that surfaces coated with passive cooling paint can stay up to 20°F cooler than the surrounding air under direct sunlight. In regions that face frequent heatwaves, buildings painted with this material can remain comfortable without the need for fans or air conditioning, thereby reducing energy bills and easing demand on power grids.

Second, the coating harvests water. Made with calcium chloride, the paint draws moisture from the air, which condenses and is collected in a built-in container. Even in relatively dry climates, a single square meter can yield several cups of potable water per day. Lab tests confirm that this water meets drinking standards, providing a reliable source for communities facing drought, limited infrastructure, or off-grid conditions.

Passive cooling paint operates effectively both day and night effectively. Cooler nighttime temperatures increase condensation, improving water collection while continuing to moderate building heat. This feature makes it particularly useful for hospitals, schools, temporary shelters, low-income housing, and remote locations where electricity is limited or costly. Researchers note that diurnal temperature swings enhance the paint’s water-harvesting cycle, making the technology reliable across diverse climates.

By reducing reliance on air conditioning, the paint also has significant climate benefits. Globally, air conditioning accounts for approximately 10% of electricity consumption. Widespread use of passive cooling paint could ease peak grid demand, lower fossil fuel use, and reduce household energy costs, all while improving indoor comfort during extreme heat events.

Durability and ease of application are major advantages. The coating resists sunlight, dust, and corrosion, and it can be applied using standard rollers or sprayers. Field trials are underway to validate performance on larger buildings, and researchers are optimizing water collection systems for maximum efficiency. Cost estimates suggest the paint could match high-quality exterior coatings, with potential reductions through mass production. Long-term outdoor testing indicates that passive cooling paint maintains reflectivity over extended periods, reducing maintenance needs for low-income communities.

The versatility of the technology opens new possibilities. Beyond homes, the innovative paint could be applied to bus stops, warehouses, greenhouses, temporary shelters, agricultural facilities, and even data centers. Coated surfaces not only reduce heat but also support the generation of potable water, creating a dual benefit that requires minimal infrastructure. Transportation hubs and emergency shelters are already being considered for pilot installations due to their high exposure to heat.

This system complements other climate adaptation strategies. Communities can pair the paint with rainwater collection, solar pumps, or other low-cost solutions to boost resilience. The approach avoids rare materials, complex machinery, and specialized labor, relying instead on simple physics and ambient air conditions.

In urban environments, reflective rooftops coated with passive cooling paint could reduce the heat island effect, lowering street temperatures and improving public safety during heatwaves. Combined with its water-harvesting capability, the paint provides both immediate relief and long-term resilience.

Passive cooling paint highlights how materials science can address multiple challenges simultaneously. It offers sustainable, low-maintenance cooling while generating potable water, providing practical relief for communities facing heat and water stress. As field trials continue and production scales up, the technology has the potential to reach thousands of households and public facilities worldwide. Small adjustments to everyday surfaces could yield significant benefits for energy use, water security, and public health, proving that innovative thinking can create resilient communities.