Vermont manufacturer introduces low-embodied carbon building material to US

Glavel offers foam glass gravel made from recycled glass. This fall, the company is scheduled to open a manufacturing facility in Essex. Photos by Erica Houskeeper
Made from recycled glass, Glavel will begin manufacturing foam glass gravel at its Essex facility this fall.

by Kelly Notterman “The built environment is responsible for nearly 40 percent of greenhouse gas emissions,” said Rob Conboy, founder and CEO of Glavel. “There is the energy we use to heat and cool buildings, which most people understand, but the materials used in construction also have a big impact.”

Specifically, building industry professionals are now taking into consideration embodied carbon—a term that refers to the carbon dioxide emissions of materials throughout the entire manufacturing and construction process—to understand a building's true carbon footprint. That includes emissions from transportation of heavy materials, such as stone, and whether the materials are derived from or manufactured with petroleum, for example.

Glavel offers a low-carbon alternative to the crushed stone and foam board typically used under the slab of a building to provide drainage and insulation—namely foam glass gravel made from recycled glass.

“Our product requires no virgin glass or petroleum products,” said Conboy, “and it’s ultra-lightweight so it reduces transportation emissions.”

Also known as cellular glass, foam glass gravel is a lightweight aggregate made from recycled glass that has been used in Europe for more than 25 years. “It’s a proven product,” said Conboy. “It’s better for the environment, cost-effective, and streamlines logistics on a job site by combining drainage and insulation properties into one product.”

Rob Conboy, founder and CEO (left front) and Ken Mincar, COO of Glavel (far back), brainstorms with sales manager Alexandra Carroll and sales and marketing staff member Tor Dworshak.

More than an upcycling story.

When Ardaugh, one of the main glass recycling plants in the U.S. closed without notice in 2018, Conboy saw an opportunity to create a new market for upcycled glass. “It sent shock waves through the recycling chain,” he said. “Everyone was asking what we were going to do with all of our glass recycling?”

Conboy founded Glavel and began importing foam glass gravel from Europe. His plan was to introduce the product to the U.S., build up a customer base, and eventually open a domestic manufacturing facility—all while helping to solve the country’s glass recycling problem. “In the beginning, I thought Glavel would be an upcycling story,” said Conboy.

In the years since, however, the building industry has begun to move aggressively toward materials with low-embodied carbon, creating another strong selling point for foam glass gravel. The Institute of Architects now calls for “building transparency” that accounts for embodied carbon used in building materials and the impact of those materials on the environment and climate change.

Recognizing the opportunity, Conboy and his team decided to make the leap to domestic manufacturing sooner rather than later. In need of working capital, Conboy approached the Flexible Capital Fund (Flex Fund) in late 2020 to help make the transition from an import business to a manufacturer. The Flex Fund worked with Coastal Enterprises, Inc. (CEI) of Maine, a Community Development Financial Institution (CDFI) similar to the Flex Fund, to round out a $400,000 financing package using royalty (also known as revenue-based) financing.

“CEI and the Flex Fund are mission aligned and we’ve worked together before, but this was the first royalty financing they had done,” said Janice St. Onge, president of the Flex Fund. “CEI was more comfortable with us as the lead investor and willing to take the risk with Glavel. Together, our organizations can support Glavel far beyond the borders of Vermont.”

This company’s scheduled opening of a manufacturing facility in Essex, Vermont this fall can’t come soon enough. This month, the International Panel on Climate Change delivered their starkest warning yet about the deepening climate emergency, with some of the changes already set in motion thought to be “irreversible” for centuries to come. Despite the dire warnings contained in the report, Conboy is optimistic that companies like Glavel can be part of the solution.

“We have the technology today to make significant progress on climate change,” he said. “While innovation is important, the road to getting us out of the climate change problem is paved with known technologies that exist today. We just need to scale these solutions.”

Manufacturing aligned with social, environmental values.

As they do just that, Conboy and his team are determined to scale in line with the company’s values and mission, which are particularly evident in the company’s clean energy commitment and hiring policy.

The process of making foam glass gravel includes slowly moving glass powder through a 1,600°F furnace to create the pumice stone—an energy intensive process. Conboy pledged early on to power manufacturing with all renewable energy—a promise he is working with Green Mountain Power and Encore Renewable Energy, another Flex Fund portfolio company, to deliver.

But Conboy doesn’t stop with recycling and clean energy. Influenced early on by his work with progressive companies such as Seventh Generation and environmental justice leaders like Van Jones, Conboy is adamant that “we can’t solve environmental problems unless we also tackle social justice problems.”

To that end, Glavel has partnered with Working Fields, a Vermont staffing agency that gives a second chance to people who have been incarcerated or are recovering from addiction, and will be activating that partnership this year as he begins to staff up the new plant. “Giving people a second chance through employment is how we begin to break the cycle of incarceration,” said Conboy. Additionally, as he builds his team and governance structure, Conboy is committed to ensuring his team is diverse and inclusive, understanding the value that having a broad range of perspectives brings to a business.

“We believe in environmental stewardship, social justice, and a clean energy future,” said Conboy. “As a business owner, I have an opportunity and a responsibility to be true to those values and ideals, and to integrate them into every aspect of the company.”

About the Flexible Capital Fund

The Flexible Capital Fund, L3C is a Community Development Financial Institution (CDFI) and impact investment fund that provides flexible risk capital in the form of subordinated debt, revenue based financing (also known as royalty financing) and alternative equity structures, to growth-stage companies in Vermont and the region’s food systems, forest products, and clean technology sectors.

Kelly Notterman is the Vermont Sustainable Jobs Fund Communications Director.