Campus Instructional Facility (CIF) has quickly become an on-campus hub, drawing tens of thousands of students per week through its doors. A wide array of classes are there, and public space areas are often populated as study areas. The building went up in 2021 and in these years since, F&S Retrocommissioning (RCx) experts figured it likely they would work on the building, with its high usage and advanced mechanical systems.
CIF was also introduced as a geothermal-powered facility, meaning it draws on the relative stability of below-earth temperatures to keep the building warm or cool, depending on need. Special windows prevent hot temperatures, and change colors. Panels in individual rooms keep users comfortable. The air handling unit has dual energy recovery wheels, rooms have CO2 and humidity sensors, and it was designed with good window and wall insulation and air sealing. The building was given a LEED® Platinum rating once built, one of just five on the Urbana campus.
But there’s always room for improvement, and RCx efforts have resulted in a 38%drop in energy use (kBtu/ft2/year). Here’s how.
RCx Prescriptions
Retrocommissioning teams make solutions happen – a team is deployed to the site with the express goal of, through hardware, software, education, and investigation, making the building more effective at heating and cooling its occupants. RCx has made improvements to more than 350 buildings totaling a cost avoidance of $160M since 2007. Occupancy is one piece of low-hanging fruit within reach of most any building’s energy use reduction plans. Ideally, you should use less energy when there’s fewer people in the building, like at night, during unscheduled days, holidays or break periods, and in summer months.
Bringing 40,000 students through each set of doors per week raises periodic peak needs — as they open the door to enter or exit, more conditioned air will need to offset that fresh air that just swept inside.
Andy Robinson, F&S engineer in energy services administration, was on the team addressing CIF concerns. The results, says Robinson, have made CIF a “contender for most efficient building on campus, especially one that has so many students in it.”
“We save a lot of energy in large campus rooms by turning down the airflow based on the CO2 demand or when nobody is there at all,” said Robinson. “Every room at CIF already had CO2 sensors, but the program wasn’t letting the air go as low as we determined it could. CIF is the busiest classroom building on campus, but there are still plenty of hours when rooms were sitting empty or with one person keeping it running too high.”
6 Solutions
A few improvements were made simply done thanks to metering findings done by Robinson and the RCx team.
- For one, the primary air handling unit would run all through the night hours and early morning in times when the building is empty. This was solved with some adjustments made to in-room sensors.
- Secondly, a chilled water valve, which is a backup to cool the building, would not close all the way. They spotted this hardware issue and worked with their team of dedicated F&S craftspersons – sheet metal workers, temperature control mechanics, and electricians are teamed with engineers and programmers to get on site and get it done.
- Thirdly, classroom use in summer months have seen “very limited” use, and many are very large, so using the CO2 sensors is even more important.
- Fourth, the radiant panels which keep comfortable temps in each room are fairly unique on campus, especially paired with a geothermal heat recovery chiller, and they required special programming. Areas like the radiant heated concrete monument steps are an ideal warm place on a cool day.
- Fifth, some locations of plumbing show water chemistry issues, leading to valve failures in the heat recovery chiller. This has now been humming along well for the past year.
- Sixth, the amount of campus-generated steam should go down based on preheat and reheat temperatures changing to a lower temperature. The building does a great job of keeping its heat in and needing very little cooling/steam needed from campus.
The project lasted March until June in 2024, and results have been impressive.
Electricity use is down 6% (in kWh), chilled water reduction of 72% and a steam reduction of 52%, with more expected this winter.
“For saving energy, reducing the room load and the 100% outdoor air is the first step,” said Robinson. “Last winter we were able to cut the campus steam to the air handler to essentially 0 by lowering the water temperature from 160 to 115F, which the geothermal HRC production on-site can produce. We can do this because the dual heat recovery wheels are so efficient at extracting the exhaust heat and preheating the outdoor air, and because the building is so well designed.”
Lessons learned from the design and construction of CIF have been incorporated into the Gies College of Business’ new Wymer Hall. This is the newest geothermal high efficiency classroom/office building, and it will be interesting to see how the two stack up in energy once the commissioning bugs are worked out.