AC usage to escalate as the planet heats up. A Harvard startup provides an answer.

Currently, cooling systems used in buildings contribute to as much as 4 percent of global greenhouse gas emissions. While it might seem like a minor amount, it is significant: double the emissions linked to all air travel, for instance.

As global temperatures rise because of climate change, the requirement for cooling is predicted to increase dramatically. The demand for air conditioning is projected to skyrocket by as much as 40 percent by 2030. Energy consumption, along with the related climate-changing emissions, will surge in tandem.

“There’s an answer to climate change here,” stated Jonathan Grinham, assistant professor of architecture at Harvard’s Graduate School of Design. “The issue is substantial, and the market potential is considerable.”

In spite of the impending demand surge, the technology employed for cooling spaces has stayed almost unchanged for more than a century. “We’ve been entrenched in the status quo of larger industries providing the same vapor-compression technology,” remarked Grinham.

Trellis Air, a startup from Harvard, aims to disrupt that norm. Through collaborative efforts throughout the University, the company has recently emerged with aspirations to significantly minimize the energy required to operate air conditioners with its innovative dehumidification technique.

‘Fusion of fundamental science and engineering advancements’

The majority of air conditioning units aren’t significantly different from enhanced dehumidifiers. A cooling system draws in air at room temperature and cools it using substances known as refrigerants. The water vapor extracted from the air is condensed, leading to that notorious “drip, drip, drip” associated with air conditioners, while the cooler air is circulated into the environment and heat is expelled outside.

Air conditioning technology also extracts moisture from the air, and dehumidifiers operate similarly to remove water from the surrounding air. The chilled, dry air is then reheated before being released back into the space.

“A dehumidifier consumes a large amount of energy,” explained Russ Wilcox, CEO of Trellis Air. “It’s comparable to driving with one foot on the accelerator and the other on the brake: one part is creating cold, while the other is generating heat.”

While refrigerants, which have considerable climate-warming potential, form the basis of most current cooling systems, certain industrial operations requiring extremely dry air might opt for a desiccant air dryer— a system that uses a medium like salt to capture moisture.

Trellis Air, conversely, will depend on a “third approach” to extracting moisture from the air, Wilcox remarked. Harvard researchers have developed an innovative membrane capable of directly separating water vapor from the air— akin to a coffee filter. This system consumes significantly less energy than conventional air conditioners and dehumidifiers and offers greater stability than desiccant systems.

To develop the foundational technology, Grinham collaborated closely with staff scientist Jack Alvarenga and others in the lab of Joanna Aizenberg, the Amy Smith Berylson Professor of Materials Science at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS) and a professor of chemistry and chemical biology at Harvard. Drawing on his extensive knowledge of architecture and building science, Grinham teamed up with Alvarenga and other members of the Aizenberg Lab to prototype materials and undertake the essential science needed for the creation of Trellis Air’s product.

The Wyss Institute for Biologically Inspired Engineering facilitated the team’s initial investigation into building cooling technology, aiding the discovery process. This financial backing, along with support from Harvard’s Office of the Vice Provost for Climate and Sustainability and the U.S. Department of Energy, enabled Grinham, Alvarenga, and their colleagues at SEAS to innovate new technology and subsequently approach Harvard’s Office of Technology Development (OTD) for assistance in bringing their innovation to market.

Previous attempts at membrane dehumidification systems faced challenges in achieving high selectivity for water with scalable and durable materials. In addition to creating an effective membrane, the Harvard team engineered an original, 3D-printed tile assembly allowing water to flow through easily while safeguarding the delicate membrane, which measures just 15 microns in thickness— thinner than a human hair— for extended periods.

“It represented a beautiful fusion of fundamental science and engineering breakthroughs,” remarked Christopher Petty, OTD’s business development director for physical sciences.

‘If he recommends something is worth witnessing, it typically is worth witnessing’

OTD secured the intellectual property of the innovations produced at Harvard and licensed it to Trellis Air for further advancement. Grinham and Alvarenga will continue to participate as scientific advisors to the firm, alongside Aizenberg and Martin Bechthold from the School of Design.

Petty,a previous entrepreneur himself, wasn’t initially acquainted with the kind of technology Grinham and the research team aimed to create. However, what he discovered about the magnitude of the air conditioning issue took him by surprise, and convinced him of the enterprise’s possibilities.

“Sometimes it’s sufficient that it’s a good enterprise, it has to be,” states Petty. “But if you feel you can engage in something that might have such an impact, then it helps you rest at night too.”

He started reaching out to locate an entrepreneur who could guide the concept from technological innovation to substantial business.

Wilcox, an entrepreneur transformed venture capitalist who had previously popularized the electronic paper-display technology now utilized in millions of Kindles, was among Petty’s initial contacts. His interest was instantly aroused. “If he recommends something is worth examining, it’s typically worth examining,” remarks Wilcox.

Still, it required more than a dozen discussions before Wilcox chose to become the firm’s CEO. From the outset, Wilcox believed that the opportunity was immense, owing to the sheer scale of the AC sector, but he decided to take the plunge after discovering that several former colleagues from his previous company, E Ink, were prepared to join him.

Launching a company he had faith in with former coworkers “just appeared to be the most blissful thing I could undertake,” he stated. “Nothing could be more thrilling.”

Wilcox envisions three pathways to commercialization for Trellis Air: replacing desiccant systems in industrial settings, exchanging basement dehumidifiers for more efficient ones, and the major gamble: combining Trellis Air’s technology with air conditioners globally. Wilcox claims the company will promote the tech as a “pre-drying module” that will enable ACs to operate with significantly higher efficiency, using substantially less energy.

The CEO has supported nearly twenty enterprises as an investor, and sees substantial opportunities for Trellis Air, partly due to the vast potential reward. “For a deep-tech startup to succeed, you require a significant, ambitious goal that everyone will agree is worth the risk,” he stated. The scale of the air conditioning issue matches that criterion.

To mitigate the risks associated with the technology and demonstrate its viability, Trellis Air has been engaged in prototyping over the past year. Prior to the company’s launch, a proof-of-concept prototype was tested in Miami through the team’s Department of Energy Grant with Forrest Meggers at Princeton University and Les Norford at MIT. Subsequently, the crew evaluated a fully integrated system at Harvard’s HouseZero, the hub of the Harvard Center for Green Buildings and Cities, retrofitted as a “living lab” to examine and gather data on the technology’s efficiency in a real-world context. These demonstrations illustrated what Trellis Air’s technology can accomplish during Boston’s sweltering, humid summers and the even more inhospitable Miami climate.

Those practical examples should help instill confidence in funders regarding the system’s capabilities.

“It’s one thing to create energy models to suggest that this is feasible, and it’s a completely different matter to successfully deliver the physical prototype at scale,” noted Alvarenga. “We were able to actualize the concept in the lab and then progress beyond the lab into pilot field studies. With Trellis Air, we aim to advance further and scale up a commercial product that can significantly diminish the future vast energy and emissions requirements of cooling.”

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Harvard IP licensed to Trellis Air was partially funded by the Department of Energy and National Science Foundation.