Monitoring-Based Commissioning at Atkinson Hall, UC San Diego
Recently completed monitoring-based commissioning (MBCx) at UC San Diego’s Atkinson Hall demonstrates successful implementation of a wide range of energy efficiency and maintenance measures, leading to six-figure annual savings with less than a half-year payback (counting incentives). The project also led to better control of laboratory equipment and provided training for staff to maintain energy savings. Operational cost savings amounted to $230,000 per year, with a net cost to the campus of just over $100K.
Annual energy savings of 26% with cost savings of $230K were achieved by first targeting a set of known problems, and secondly through diligent attention to long list of repairs and improvements to HVAC sensing and control.
The eight-story Atkinson Hall was completed in 2005 and houses offices, laboratories, clean rooms, data centers and a large auditorium. The building supports important research activities, including the highly regarded California Institute for Telecommunications and Information Technology (the building is also referred to as Calit2). The sensitive nature of many research activities required that the MBCx team understand the nature of these diverse building functions and to avoid interruptions to building users.
The building was selected for commissioning as it was one of the most energy intensive buildings on campus, with a peak demand of over 1 MW, and an energy use intensity (EUI) of 32 kWh/ft2/yr. This is well over the average EUI for similar academic buildings, of 12 kWh/ft2/yr, according to the California End Use Survey (CEUS).
Ductwork of dedicated cooling installed in the photonics lab.
In planning for the commissioning program, the project team led by Enpowered Solutions became aware of both assets and challenges. The building was equipped with full direct digital control (DDC) to the level of individual zones, and was maintained by operators who were knowledgeable about problems and potential barriers. On the other hand, there had been ongoing problems with high energy use, building pressurization, economizer operation failures, and with managing high heat loads in the photonics laboratory.
The project team focused initially on these issues and other measures that would yield the biggest savings, what they referred to as the ‘big hitters.’ One issue was in the photonic systems laboratory, where advanced technologies such as fiber optical communications are studied, using equipment that produces constantly high heat loads. The lab had previously been moved to a space designed for offices, requiring the large air handling unit (AHU) serving eight floors to supply very cold air constantly, even when loads in the building are low otherwise, and causing overcooling in other areas. The MBCx team solved this issue by installing a dedicated fan coil unit adjacent to the lab to provide primary cooling to the space, allowing the AHU to supply air at temperatures appropriate to the overall building load. This measure reduced occupant complaints from overcooling, allowed for better control of lab equipment, and is providing savings estimated at over $39,000 per year.
Another important MBCx measure involved the adjustment of minimum airflow rates. In non-critical spaces such as offices and conference rooms, airflow rates had been based on reheat coil requirements, rather than the minimum ventilation requirements. The solution was reprogramming airflow rates to required minimums, in most cases 0.15 CFM/ft2, when supply air was not needed for heating and cooling (at “deadband” temperatures). This also led to less discomfort from accidental overcooling, and is saving an estimated $18,000 annually.
A third 'big hitter' was the repair and replacement of economizer dampers that had failed repeatedly, primarily due to corrosive salt air. The project team installed corrosion-resistant stainless steel dampers and electronic actuators, leading to reliable economizer operation, reduced maintenance, and annual cost savings of $14,000.
In addition to solving these critical issues, the project team identified and addressed a long list of problems. They addressed building pressure issues by installing sensors in affected areas and reprogramming fan speeds to maintain the correct pressure levels. They repaired VAV box dampers and sensor housings, replaced leaking chilled water valves, relocated poorly placed sensors, and made extensive changes to operational sequences. The MBCx findings included 89 system deficiencies, of which 13 were classified as major efficiency problems. Eleven of these were addressed during the course of the project.
While the project demonstrates successful optimization of equipment and control sequences, it also illustrates the value of close collaboration with building operators, who were consulted regularly during the process. Team members credit the project success to the experience of building operators, and how this informed the MBCx processes. Upon closeout the team provided training and documentation, including an updated systems manual, and they outlined additional improvements to be addressed in the future that together could provide approximately $50,000 in additional cost savings.
Top photo copyright UCSD. Smaller images courtesy of Enpowered Solutions.