One of the few tests that RMF Engineering was able to execute with an empty building was an emergency power test. The testing was coordinated with four different teams on campus so that during the power outage electrical metering could be installed concurrently with the outage. The test was conducted during a vacation week for students to allow for multiple attempts in the event that any tests weren’t executed as planned.
During the emergency power test, RMF Engineering walked the building to ensure the emergency lighting and mechanical systems on the emergency power were operating as intended. During the walk-through, RMF Engineering found that 43 of the 99 fume hoods in the building had sashes in full-open position. Many of the fume hoods that were open were used in teaching laboratories and no hazardous materials were stored in them. The fact that the sashes were open was causing over-ventilation of the laboratory spaces and led to energy waste during unoccupied periods. Therefore, one of the ECMs put forward was renovated fume-hood controls. After evaluating multiple options for renovation, a final ECM was proposed to renovate fume-hood controls to include automatic sash closers and hibernation modes and to reduce face velocities to 100 feet per minute. RMF Engineering evaluated fume hoods to ensure retrofit kits could be accepted without needing to replace the hoods. The project recommendation was put forward at an annual savings of $126,794 and a simple payback time of six years.
Another unforeseen benefit of re-commissioning an occupied building was that it facilitated student learning activities. Oberlin College was unique in its scope of work for re-commissioning in that there was a requirement to include student involvement and educational opportunities. RMF Engineering worked with students and interns from the college’s sustainability programs to educate them about commissioning processes. Students also received safety training and were provided the proper safety equipment and personal protective equipment to follow along on building walk-throughs and commissioning activities.
One of the unexpected outcomes of the re-commissioning project was the coordination challenge of balancing the building needs and the needs of the district energy systems, as well as the needs of other buildings on campus. The chilled water system for the building was district-chilled water when the campus chiller plant was enabled and was supplemented by a local air-cooled chiller in the winter and swing seasons. The team discovered that the chilled-water system operation and capacity occurred during outside air-temperature swings. The standard operating procedure for the campus was to enable the campus-chilled water plan after there were two consecutive weeks of outdoor temperature above 60 F. This led to instances where high outdoor air conditions occurred and no plant-chilled water was available.
Upon evaluating the local air-cooled chiller capacity and the connected cooling loads, RMF Engineering found the local chiller and pump capacities were 247 tons at 575 gallons per minute (GPM) while the connected load was 888 tons at 1,538 GPM, plus some additional unknown load from unscheduled and customized air handlers. This equates to the local chillers and pumps only capable of accommodating 24 to 27 percent of the cooling load of the building. The team witnessed ambient conditions inside the building of 80 F and 70 percent relative humidity (RH). This affected occupant comfort and the accuracy of laboratory research projects.
The heating system for the building was comprised of district steam serving heat exchangers within the building with local boilers used in the summer months for terminal equipment re-heat purposes. The team discovered that all heating equipment renovated in 2000 was sized for medium pressure steam at 25 pounds per square inch (PSI). During heating system evaluations, RMF Engineering discovered that district steam from the Central Steam Plant varied but was typically between eight and nine PSI with occasional drops to six PSI in the main 10-inch incoming steam line. Because of the reduced district steam delivery pressure, the Science Center was starving for heat and was typically cold in the winter months, rendering some areas, such as the greenhouse, nearly unusable. Additionally, nearly all the heating system components were operating at full capacity 24 hours a day throughout the winter, and all steam metering was unreliable as the meters installed were not sized for low pressure steam.
Both the cooling and heating system operation needed to be addressed with central plant personnel. Through discussions with the appropriate personnel RMF was able to learn more about why the cooling and heating systems were manipulated to work as they currently were. In particular, the team was informed that the steam delivery pressure was reduced significantly and intentionally because of undersized and failing pressure reducing valve stations elsewhere on campus. RMF was able to work with the central plant personnel to identify these locations that were originally outside the scope of the re-commissioning project to include them in capital project recommendations put forward to the project team.
Although the challenges were extensive, the Science Center at Oberlin College is proof that successful recommissioning of occupied, existing buildings can take place through thoughtful planning, coordination and communication across the project team.
Learn More from RMF Engineering at CxEnergy in Las Vegas
Baltimore-based RMF Engineering will be presenting “Lab Retro-Cx: The Rebirth of a Research Facility” at CxEnergy 2018, a building commissioning and energy management event. CxEnergy includes educational sessions on a wide range of topics relating to commissioning and energy management of the total building enclosure, an exhibit hall featuring the latest in energy-management technologies and certification opportunities for the Washington, D.C.-based AABC Commissioning Group’s Certified Commissioning Authority (CxA) and the Washington-based Energy Management Association’s Energy Management Professional (EMP). CxEnergy is being held April 23-26 in Las Vegas. Register at www.CxEnergy.com.