Researchers at UCLA have unveiled a new method to cool buildings by manipulating the movement of radiant heat, a breakthrough that promises significant energy savings and a reduction in carbon emissions.
In a world grappling with climate change, the need for sustainable cooling solutions has never been more pressing. Researchers at UCLA have made a significant stride in this regard by discovering a cost-effective and scalable process to cool buildings during summer and heat them in winter, all while saving energy.
Under the leadership of Aaswath Raman, an associate professor of materials science and engineering at the UCLA Samueli School of Engineering, the team has detailed their innovative findings in a recent study published in the journal Cell Reports Physical Science. This research highlights a novel method to manipulate the movement of radiant heat through standard building materials, optimizing thermal management.
Radiant heat, a ubiquitous form of heat transfer carried out by electromagnetic waves, typically moves across a broad spectrum between ground-level structures but flows within a narrower spectrum known as the atmospheric transmission window between buildings and the sky. This inherent difference has posed a longstanding challenge to cooling buildings that do not have extensive sky-facing surfaces.
“If we look at historical cities like Santorini in Greece or Jodhpur in India, we find that cooling buildings by making roofs and walls reflect sunlight has been practiced for centuries,” Raman said in a news release. “In recent years, there has been massive interest in cool roof coatings that reflect sunlight. But cooling walls and windows is a much more subtle and complex challenge.”
Building on the successful precedent of super white paint on roofs that reflect sunlight and radiate heat, the researchers focused on developing a passive radiative cooling effect for walls and windows. They discovered that certain materials, particularly polypropylene found in common household plastics, can effectively manage heat movement by selectively absorbing and emitting radiant heat within the atmospheric window. This enables buildings to stay cooler in summer and warmer in winter compared to conventional materials.
“We were particularly excited when we found that materials like polypropylene, which we sourced from household plastics, can selectively radiate or absorb heat in the atmospheric window very effectively,” Raman added. “These materials border on the mundane, but the same scalability that makes them common also means that we could see them thermoregulating buildings in the near future.”
This breakthrough means not only leveraging cost-effective materials but also significantly cutting down energy consumption by reducing dependency on air conditioners and heaters. Such appliances are costly to operate and major contributors to carbon dioxide emissions.
“The mechanism we proposed is completely passive, which makes it a sustainable way to cool and heat buildings with the seasons and yield untapped energy savings,” added first author Jyotirmoy Mandal, an assistant professor of civil and environmental engineering at Princeton University who conducted the study as a postdoctoral scholar in Raman’s lab.
The implications of this development are especially profound for low-income communities that often lack access to adequate cooling and heating systems. These areas have borne the brunt of extreme weather conditions, resulting in rising casualties. The new technique could offer a lifeline by providing a sustainable and energy-efficient solution to thermal management.
Raman and his team are currently working on ways to demonstrate this effect on a larger scale, focusing on heat-vulnerable areas in Southern California. The hope is that this breakthrough will not only mitigate energy expenses but also contribute towards alleviating climate change impacts.
In sum, this pioneering discovery by UCLA researchers marks a pivotal step towards sustainable building management, symbolizing hope in the face of environmental and climatic challenges.