Researchers at Drexel University have developed a novel building material that mimics the thermoregulating function of elephant and jackrabbit ears. By embedding a vascular network filled with phase-change material (PCM) within cementitious surfaces such as walls, ceilings and floors, the team has demonstrated a passive method to help buildings better regulate interior temperatures and reduce reliance on mechanical heating and cooling systems.

This innovation responds to the urgent need for improved building energy performance. Globally, buildings account for nearly 40% of total energy consumption, with approximately half used to maintain indoor thermal comfort. Traditional insulation methods have advanced, yet walls, windows, and ceilings remain key points of energy loss—up to 63% in some cases.

Nature-Inspired Climate Regulation

Drawing on biology, the Drexel researchers replicated the way vascularised tissue in animal ears helps dissipate or retain heat. In buildings, this takes the form of a 3D printed polymer matrix embedded within concrete surfaces, creating hollow channels that are filled with paraffin wax—a well-known PCM.

When ambient temperatures rise, the paraffin absorbs heat as it melts, producing a cooling effect. As temperatures fall, it solidifies, releasing stored heat and warming the surface. By tuning the wax composition, this system can be adapted to suit various climates.

Performance & Design Potential

In lab tests, the most effective design combined a diamond-pattern vascular network with a PCM melting point around 18°C. This configuration slowed surface temperature changes by up to 1.25°C per hour without compromising the material’s structural strength. The pattern also maximised vasculature surface area, much like in biological systems, to enhance thermal control.

To improve durability, the researchers added fine aggregates to the cement mix. This allowed the concrete to maintain integrity despite internal cavities for the PCM, suggesting it can meet real-world structural demands.

Sustainable Applications

This development opens new pathways for biomimetic building materials that integrate passive energy systems directly into architectural surfaces. The system is scalable, cost-effective, and flexible, enabling future designers to tailor the vascular grid and PCM composition to regional needs.

Future research will focus on testing at scale, exploring new PCM types, and refining the channel geometries. While still at proof-of-concept stage, the work underscores the potential for sustainable material design to transform how buildings interact with their environments.

Source: Drexel University
Photo: Harvey Sapir