BOZEMAN — While newly renovated Romney Hall is providing much-needed classroom space and student services at a growing Montana State University, the century-old structure's upgrade also marks progress by demonstrating that even the oldest buildings on campus can achieve high energy efficiency as part of an ambitious strategy to reduce operating costs and carbon emissions.

Originally constructed as a gymnasium in an era when leaky windows, thin insulation and fuel-intensive central heating were the norm, the repurposed Romney, which opened last November after an extensive remodel, is expected to use roughly half the energy as the old building.

“What we’ve shown here is that we can take the same technologies and strategies that we've proven with new construction and make them work with a major retrofit," said Megan Sterl, engineering and utilities director in MSU’s University Services. "It highlights how these older buildings can be a key part of our energy-saving vision for the future of campus."

At the core of the building's energy performance is a geothermal system that benefits from the relatively constant temperature deep underground. In tandem with the Romney renovation, 80 geothermal boreholes — each 700 feet deep — were constructed in the open space north of the building. The boreholes house closed-loop pipes, encased in a special grout, that circulate a water solution to store unused heat extracted by Romney Hall's ventilation system, such as when the building is being cooled. The stored warmth can later be extracted and concentrated to heat the building. Modeling by the design team shows that the annual cycle of heat storage and extraction is relatively balanced, resulting in minimal change to the ground temperature.

The boreholes also store unused warmth captured by a "solar wall" on the building's south face that converts sunlight to heat. During sunny weather in cooler months, the solar wall pre-warms the ventilation air before it’s circulated to roughly 40 heat pumps throughout the building. The heat pumps, which are like air conditioners that can also operate in reverse, are what transfer heat to and from the geothermal system. The geothermal system and solar wall provide most of the heating for the building, meaning that the main energy input is electricity that efficiently runs the heat pumps and ventilation units.

Romney joins six other campus buildings with geothermal systems. MSU first applied the technology during its biggest energy conservation project, a multi-phase effort in 2011-2015 that was integrated with the construction of Jabs Hall. The Jabs geothermal system, which also serves three other MSU buildings that are much newer than Romney, has reduced energy costs by an average of $130,000 per year. Norm Asbjornson Hall, which opened in 2018, as well as the recently completed American Indian Hall, also each have geothermal systems.

Compared to those projects, however, integrating a cutting-edge geothermal system into Romney's 98-year-old structure was a challenge, according to Michael Bowers, project manager in MSU's Campus Planning, Design and Construction, who oversaw the Romney renovation with Grant Peterson, MSU construction manager. With a premium put on space for 17 classrooms as well as centers for mathematics, writing, veterans and students with disabilities, "we had to get really creative with fitting in the heat pumps and other equipment and tying it all together," he said. "It's definitely a lot harder than with new construction, but we were able to make it happen."

The renovation included other upgrades to improve energy performance, Bowers noted. To reduce heating and cooling losses, high-performance insulation was added throughout the exterior walls, and all the windows were replaced or restored. All lighting is provided by LEDs, which use significantly less energy than traditional bulbs.

Besides demonstrating what's possible for an older building, the Romney project directly opens other opportunities for advancing energy efficiency on campus, Sterl noted. The geothermal boreholes under the Romney Oval are situated and sized so that they can also easily serve other nearby buildings, including the forthcoming Student Wellness Center, to form what's called an energy district.

That would effectively allow Romney Hall to exchange excess heat with other buildings, creating an added dimension of efficiency, Sterl said. As a result, the Romney geothermal boreholes are projected to reduce MSU's associated carbon emissions by 1 million pounds per year, or about 20,000 metric tons over the lifetime of the system — a significant step toward the goal in MSU’s Sustainability Framework of reducing its greenhouse gas emissions to achieve carbon neutrality by 2040.

A recent report by the National Renewable Energy Laboratory featured MSU's innovative use of energy districts as one of 15 case studies showing how smart planning and new technology can dramatically reduce energy consumption. Aiding in future MSU efforts, last September the Montana Board of Regents authorized the university to spend up to $500,000 on comprehensive energy planning that's expected to yield millions of dollars in energy savings over coming decades.

"Romney is just the first building to be connected to what we envision as the South Campus energy district," Sterl said. "It's the cornerstone for continued energy conservation in that part of campus."