AMHERST, Mass. — Researchers at the University of Massachusetts Amherst recently unveiled a tool to combat climate change, fossil-fuel dependency, skyrocketing home-heating bills and gentrification all at once—a simple fabric treated with a special photothermal dye that, when placed on outside walls, can help keep a home 8.64ºF warmer over the course of a day.

“Sometimes, a simple solution works best,” says Trisha Andrew, professor of chemistry at UMass Amherst, and one of the paper’s senior authors, along with Carolina Aragón, associate professor of landscape architecture, and Ho-Sung Kim, senior lecturer in building and construction technology.

“When you’re cold, you put on a sweater,” says Aragón, “so we started thinking: what would you do if you’re a building?”

Heating buildings is a huge driver of fossil-fuel consumption, greenhouse gas emissions and energy insecurity. Over 33 million homeowners in the U.S. report trouble keeping their houses warm, and more than 24 million people—often renters—report skipping food or rationing energy in order to pay for heat. Meanwhile, according to the U.S. Energy Information Administration, residential and commercial buildings account for 39.1% of the primary energy used in the U.S. Reducing heating costs also translates into an enormous reduction in CO₂ emissions.

The typical way to address an inefficient home is to tighten it up: new windows and doors, more and better insulation, etc. But if you’re a renter, these options aren’t necessarily open to you. Worse is the phenomenon of “reno-viction,” where a landlord upgrades their property and then raises rents beyond what’s affordable for their current tenants. “Too many people have to choose whether they heat or eat,” says Aragón.

But what if keeping a house snug were as easy and affordable as putting on a sweater?

Andrew, among whose specialties includes inventing high-tech fabrics that can mimic animals adapted to extreme cold—like polar bears—and Aragón, who has long worked at the community scale to tell the story of climate change, teamed with Kim, who is an expert in modeling architectural designs for their energy usage.

The team initially thought of a building blanket, but ultimately what they designed and tested looks much more like jewelry: a series of removable tiles or panels that can be hung on any surface which not only conduct the sun’s warmth but insulate the building.

The key is a special photothermal dye that Andrew invented. “We can put this dye on anything,” Andrew says. “It doesn’t have to be on an expensive fabric. We chose to test it on umbrella fabric—something that was rugged and robust but still affordable.”

When they modelled their design, the results were eye-popping.

“We saw up to a 15% decrease in energy costs for a residential building in a northern climate, like Massachusetts,” says Andrew, “and up to 23% reduction in a large, 16-story apartment building.”

By comparison, a well-done traditional home renovation might yield a 2% reduction in energy costs.

These panels could even be sold as do-it-yourself projects that any renter could complete. The team imagines a scenario where people head to their local hardware store, buy a roll of the fabric and a few 2x4s and, in an afternoon, have a cheap and effective way of helping to heat their homes.

“Because the heart of this technology is a dye, we can use it to make panels that are beautiful and blend in with the specific culture and aesthetics of an area,” says Aragón. “It’s important to get the architectural and aesthetic part of this right, in addition to the science.”

But before consumers rush out to ask for the miracle fabric, the team needs to conduct additional, real-world testing. Though they’ve proven the concept in the lab, they need more data and field tests with life-sized prototypes.

“This could have an enormously beneficial societal impact,” says Andrew, and Aragón agrees: “there’s a role for anything that is empowering at the individual scale.”

The research appears in the journal ACS Applied Engineering Materials.

Contacts: Trisha Andrew, tandrew@umass.edu

                 Carolina Aragón, caragon@larp.umass.edu

                 Daegan Miller, drmiller@umass.edu

About the University of Massachusetts Amherst 

The flagship of the commonwealth, the University of Massachusetts Amherst is a nationally ranked public land-grant research university that seeks to expand educational access, fuel innovation and creativity and share and use its knowledge for the common good. Founded in 1863, UMass Amherst sits on nearly 1,450-acres in scenic Western Massachusetts and boasts state-of-the-art facilities for teaching, research, scholarship and creative activity. The institution advances a diverse, equitable, and inclusive community where everyone feels connected and valued—and thrives, and offers a full range of undergraduate, graduate and professional degrees across 10 schools and colleges and 100 undergraduate majors.  

The elastocaloric effect allows for heat transfer through the mechanical deformation of special materials, specifically nickel-titanium alloys known as Nitinol. By simply altering the shape of ultrathin wires and sheets of this smart material, the researchers have found a way to extract heat from an environment, cooling it down in the process. The core principle lies in the material’s unique ability to absorb and dissipate heat when subjected to mechanical stress. As the wire is pulled and then released, heat is effectively moved from one location to another, demonstrating a sophisticated yet straightforward method of thermal management.

This pioneering research has not gone unnoticed. Recognized by the European Union and the World Economic Forum, the elastocaloric technology is heralded as a potential game-changer in the battle against global warming. The World Economic Forum listed it among the Top Ten Emerging Technologies for 2024, highlighting its capacity to revolutionize how we approach air conditioning and heating solutions. According to experts, the elastocaloric method’s ability to significantly reduce energy consumption places it in stark contrast to traditional systems that often rely on harmful gases and complex refrigerants.

As space cooling demands continue to rise, with predictions suggesting a potential tripling of energy requirements by 2050, the need for innovative solutions becomes ever more urgent. In Germany alone, heating and cooling consume over half of the total final energy consumption, as reported by the Federal Environment Agency. The research team aims to address this dire situation through the development of their cutting-edge technology. With the aim to commercialize within five years, the project is a reflection of growing urgency towards sustainable practices in energy consumption.

The team will showcase their advancements at the Hannover Messe, where they will exhibit their prototype elastocaloric refrigerator. Visitors can witness live demonstrations of the cooling capabilities of this innovative system, designed to operate without any environmentally damaging elements. The prototype utilizes a patented cam track system to rotate bundles of Nitinol wires around a cooling chamber. As wires are mechanically stressed and relaxed, they perform their function of heat absorption and dissipation efficiently, providing significant cooling potential.

In addressing the mechanics of the elastocaloric process, it is essential to understand the unique properties of Nitinol. This shape memory alloy possesses the ability to switch between two distinct crystallographic phases when subjected to specific thermal or mechanical conditions. Notably, this means that when the material undergoes deformation, it can transition between phases, thereby absorbing or releasing heat with remarkable efficiency. This fundamental principle can lead to temperature differentials of around 20 degrees Celsius in practical applications, underscoring the technology’s versatility.

While the concept may sound straightforward, the engineering required to bring such a system to life is profoundly complex. The Saarbrücken team has invested years of research into optimizing the cooling and heating capabilities of their prototypes, focusing on practical applications across various settings—from electric vehicles to residential buildings. In partnership with industrial allies like Volkswagen AG and research institutions such as the Fraunhofer Institute, they are delving into practical applications that will drive this technology’s integration into everyday life.

The recent funding of over €3.5 million from the German Federal Ministry underscores the project’s significance and potential. With the success of continuous mechanical phase transformations, the Saarland University team has the ambitious goal of identifying the best applications—whether it be in home appliances, industrial cooling systems, or even mobile uses like electric vehicle air conditioning. This multi-faceted approach ensures that elastocaloric technology isn’t relegated to one sector but instead becomes a versatile solution for a range of energy needs.

The core design of the elastocaloric fridge hinges on its self-sensing technology, which employs artificial intelligence to monitor the system’s performance continually. This capability ensures precise control over temperature management, even in the face of external environmental changes. By correlating electrical resistance values to the states of deformation, the system adapts efficiently to varying conditions, thus enhancing both performance and reliability in real-world applications.

In a broader sense, the research in Saarbrücken aims to pave the way for sustainable cooling methods that will not only address energy consumption but also contribute positively to the urgent global challenge of climate change. The potential ramifications of a widespread adoption of elastocaloric systems span from individual household improvements to vast industrial applications, ultimately reducing reliance on fossil fuels and preserving valuable resources.

As this innovative technology advances, the future looks promising for the development and application of elastocaloric systems. With exemplary research underpinned by solid engineering principles, the team at Saarland University is exemplifying a commitment to transforming the landscape of air conditioning technologies. Their recent achievements serve as a reminder of the incredible possibilities that lie at the intersection of creativity, science, and dedication, encouraging a societal shift towards more energy-conscious living.

As they prepare for further trials and the ultimate goal of commercialization, the researchers remain optimistic about elastocaloric technology’s potential to reshape future market dynamics. Their ongoing commitment to excellence and sustainability offers a beacon of hope in an ecological landscape ripe for innovation and reevaluation in how we manage our energy consumption.

Subject of Research: Elastocaloric Technology in Sustainable Cooling Systems
Article Title: Innovating Sustainability: The Coming Era of Elastocaloric Technology
News Publication Date: October 2023
Web References: None
References: None
Image Credits: Oliver Dietze
Keywords: elastocaloric effect, cooling technology, sustainable air conditioning, nickel-titanium, Nitinol, Saarland University, energy efficiency, climate change.