Cooling buildings efficiently while minimising energy consumption is a critical challenge in sustainable architecture and design. Researchers at POSTECH and Korea University have developed an innovative passive material that reflects heat, significantly reducing indoor temperatures without compromising transparency. This advancement offers considerable potential for architects, interior designers, and sustainable product developers seeking energy-efficient and environmentally friendly solutions.

Natural light enhances interior aesthetics and occupant well-being, but glass windows often pose challenges with heat management. Standard windows allow around 80% of solar heat to penetrate, leading to elevated indoor temperatures and reliance on energy-intensive cooling systems. This new coating material, however, can reduce surface temperatures by as much as 40°C, offering a sustainable solution to this problem.

Material Structure and Functionality
The innovative material comprises three distinct layers, each designed for specific thermal and optical properties. The top layer is made of polyvinylidene fluoride (PVDF), a polymer that reflects infrared radiation responsible for heat. It absorbs minimal visible light, maintaining transparency while shielding interiors from heat. The middle layer consists of a mixture of silica air layers with micro-scale holes that optimise light scattering and minimise heat transfer, ensuring a balance between thermal insulation and light transmission. The bottom layer features a nano-scale zinc surface designed to reflect long wavelengths of sunlight, further preventing heat absorption while allowing visible light to pass through. Together, these layers create a synergistic effect, significantly lowering surface temperatures while maintaining natural light transmission. Unlike conventional reflective coatings, which often compromise aesthetics or require energy to function, this material operates passively and is fully transparent.

Applications in Sustainable Design
The potential applications of this material extend across various design disciplines. In architectural design, it is ideal for energy-efficient buildings, reducing reliance on air conditioning, particularly in urban settings where heat management is crucial. For interior design, it enhances indoor comfort by maintaining cooler interiors without sacrificing natural light, improving the quality of living spaces. Furthermore, in automotive and product design, it is adaptable for vehicle windows or other products requiring heat management without blocking visibility. The passive nature of this material also aligns with circular economy principles by reducing operational energy demands and contributing to overall carbon footprint reduction.

Future Implications
As the demand for sustainable and circular materials grows, this heat-reflective coating has significant implications for reducing energy consumption and promoting eco-friendly design. The researchers note that further refinement could enable wider applications, including dual-phase functionality to manage heat in summer and retain warmth in winter.

“This technology is a milestone in passive cooling solutions and has enormous potential for environmentally responsible design,” said Professor Linhui Hou, one of the study’s authors. “It offers an accessible and scalable alternative to traditional heating and cooling systems.”

The study was published in the journal Advanced Functional Materials and represents a breakthrough in material innovation for sustainable design.

Source: New Atlas
Photo: Albertfotofilms