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Ground Source, Solar, and Hybrid VRF: How Weber State Is Reaching EUIs as Low as 23 Across Its Campus
Weber State University's Lindquist Hall is a social sciences building on the Ogden, Utah campus. The building contains complex equipment, including fume hoods and laboratories. During a recent renovation, it grew from just over 100,000 to about 120,000 square feet. It also transitioned off the campus steam system, moving from gas-burning steam boilers to heating and cooling powered by a dedicated ground-source field and water-source heat pumps, with its own solar array. The site EUI dropped from about 140 to 23 kBtu per square foot per year. The annual utility cost fell from roughly $180,000 to $10,000-$15,000.
That result came from combining three technologies: ground source energy, solar, and variable refrigerant flow. Total electricity consumption fell from 1.8 million kWh annually to about 800,000 kWh, indicating the building reduced overall energy use while fully electrifying. The $1.7 million solar array next to the building was funded entirely from energy savings generated by the broader energy management program.
The ground source piece involves tapping into stored solar energy in the earth itself. Below about 10 to 15 feet, the ground temperature on the Wasatch Front (where Weber State is located) stays around 55 degrees Fahrenheit year-round; warm enough for Weber State's water-source heat pumps to run efficiently regardless of how cold the surface gets. The chilled water loop that previously served the campus for conventional cooling has been repurposed as a low-temperature condenser loop, connecting buildings to both ground source fields and the heat pump systems. VRF systems handle zone-level heating and cooling distribution within buildings, working in combination with the ground-source infrastructure.
VRF has been Weber State's primary HVAC electrification solution, but it took six or seven iterations to arrive at an approach the team was comfortable with. The most persistent challenge was refrigerant leaks. A typical VRF installation runs soft copper refrigerant pipe throughout a building's ceiling plenums — 1,500 feet or more on a single system — and when a leak occurs, it can be nearly impossible to locate. The team's latest evolution is hybrid VRF, commissioned in August 2025, which keeps refrigerant only between the compressor and the branch controller. All terminal units are served by water from that point forward.
Owen's technology philosophy throughout has been to avoid unicorns. Every system Weber State has deployed, ground source, water source heat pumps, VRF, and solar, is established technology. The battery storage system currently under construction, a 10 MWh, 5 MW installation, will enable more solar deployment, generator replacement, microgrid capability, and demand shaving. That too follows the same pattern: proven technology, funded by the savings the program has already generated.
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Weber State University's Lindquist Hall is a social sciences building on the Ogden, Utah campus. The building contains complex equipment, including fume hoods and laboratories. During a recent renovation, it grew from just over 100,000 to about 120,000 square feet. It also transitioned off the campus steam system, moving from gas-burning steam boilers to heating and cooling powered by a dedicated ground-source field and water-source heat pumps, with its own solar array. The site EUI dropped from about 140 to 23 kBtu per square foot per year. The annual utility cost fell from roughly $180,000 to $10,000-$15,000.
That result came from combining three technologies: ground source energy, solar, and variable refrigerant flow. Total electricity consumption fell from 1.8 million kWh annually to about 800,000 kWh, indicating the building reduced overall energy use while fully electrifying. The $1.7 million solar array next to the building was funded entirely from energy savings generated by the broader energy management program.
The ground source piece involves tapping into stored solar energy in the earth itself. Below about 10 to 15 feet, the ground temperature on the Wasatch Front (where Weber State is located) stays around 55 degrees Fahrenheit year-round; warm enough for Weber State's water-source heat pumps to run efficiently regardless of how cold the surface gets. The chilled water loop that previously served the campus for conventional cooling has been repurposed as a low-temperature condenser loop, connecting buildings to both ground source fields and the heat pump systems. VRF systems handle zone-level heating and cooling distribution within buildings, working in combination with the ground-source infrastructure.
VRF has been Weber State's primary HVAC electrification solution, but it took six or seven iterations to arrive at an approach the team was comfortable with. The most persistent challenge was refrigerant leaks. A typical VRF installation runs soft copper refrigerant pipe throughout a building's ceiling plenums — 1,500 feet or more on a single system — and when a leak occurs, it can be nearly impossible to locate. The team's latest evolution is hybrid VRF, commissioned in August 2025, which keeps refrigerant only between the compressor and the branch controller. All terminal units are served by water from that point forward.
Owen's technology philosophy throughout has been to avoid unicorns. Every system Weber State has deployed, ground source, water source heat pumps, VRF, and solar, is established technology. The battery storage system currently under construction, a 10 MWh, 5 MW installation, will enable more solar deployment, generator replacement, microgrid capability, and demand shaving. That too follows the same pattern: proven technology, funded by the savings the program has already generated.
Register for the next Nexus Labs event.
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This is a great piece!
I agree.