Research Triangle Park in North Carolina is the largest research park in the United States. RTP is home to more than 250 businesses that have developed an abundance of engineering and life- science technologies, “from the UPC barcode to life-saving HIV drugs.”1 An important priority for these businesses is maintaining optimal physical operations at their facilities, both for employee comfort and the precise laboratory environments needed to advance their work.
In 2017, one RTP company undertook a facility improvement project that will have long-lasting impacts on their success. The facility is more than 400,000 square feet under-roof and houses a myriad of life-science research labs and ancillary operations. The project centered on the facility’s HVAC system, and the Site Operations Manager knew they needed an engineering firm with the expertise and innovation to develop a customized project design.
Challenge
The facility’s central energy plant includes a boiler- based hot water system and four water-cooled chillers to maintain a comfortable and research-friendly indoor environment, which is particularly challenging during the hot and humid North Carolina summers. Chillers 1 and 2 were at the end of their useful life after operating for more than 30 years, producing only 300 to 350 tons of cooling despite being designed for over 400 tons. This resulted in the system being unable to meet the peak cooling load during the summer months. The two chillers were also very unreliable and required repairs at an increasing frequency and cost. In addition to the chiller inadequacies, the large size of the facility makes it difficult to pump adequate chilled water to the peripheries of the plant. The chilled water piping totals more than 4,000 linear feet, with the longest pipe run at nearly 1,000 feet. At these distances, the existing chilled water pumps were simply inadequate to maintain proper temperatures in remote areas of the facility. As the Site Operations Manager describes, “They were pumping as much water as they could but it was not cool enough and they couldn’t get it where it needed to go.”
Solution
Brady began with an extensive analysis of the previous year’s monthly cooling needs, chiller operating parameters, and pumping operations. They quantified the number of days the facility required different cooling loads and determined how well the existing chillers and pumps had responded to those demands. In addition to gathering quantitative data confirming the inadequacies of chillers 1 and 2 to meet the facility’s cooling loads,
Brady identified issues other consultants had missed such as low chilled water LH and secondary chilled water pipe size constraints. Based on the facility’s vastly different needs throughout the year, Brady recommended replacing aging chillers 1 and 2 with two new 450 ton chillers that would provide the capacity needed and allow better fine-tuning of the system to meet specific loads of different seasons. Other consultants had recommended replacing the two chillers with a single 800-ton unit. The plant engineers were inclined to agree with that recommendation, adamant that it would be impossible to get two replacement chillers into the existing equipment footprint because the boiler room configuration had changed since the original chillers were installed crowding access to chillers 1 and 2. Brady’s analysis identified more than 1,200 hours per year during which an 800-ton chiller would not be able to turn down far enough to reliably serve the building’s base load.
To provide more data, Brady conducted a 3D laser scan and modeling of the boiler room, mapping the locations of all pipes, walls, equipment, and other possible interferences. The results showed how two new chillers could be moved through the congested boiler room and into the existing chiller footprint, enabling an expedited installation without a plant shutdown or new construction to expand the plant. “Brady did a great job analyzing the boiler room and designing a new system that would work in the space available” reports the Site Operations Manager.
Brady’s approach to the secondary chilled water pumping inadequacies focused on improving the chilled water LH in the plant. The new chillers 1 and 2 were optimized to produce 40°F chilled water and provide more than 250 tons of additional cooling capacity within the previous equipment’s footprint. Chillers 3 and 4 were upgraded with the latest Trane AdaptiView”‘ unit controllers and reconfigured to also produce 40°F chilled water. All four primary chilled water pumps were reselected and replaced with appropriately sized equipment. Finally, new controls were installed to allow the primary chilled water flows to precisely track the secondary chilled water flows.
This approach eliminated wasteful over pumping, improved the chilled water LH, and reduced secondary flow rates by more than 25%. All while enabling adequate cooling capacity to the building peripheries, serving the building’s cooling needs reliably and efficiently. Other consultants had recommended increasing the size of the secondary chilled water pumps and associated piping, which would have required a disruptive plant shutdown. “Other designers would have only looked at chiller replacement, designed a system that needed a new chiller area, and extended new pipes from there,” describes the Site Operations Manager, “They wouldn’t have looked at the entire system. Brady looked at the whole system-history, chillers, loads, pumps, piping, and more, and designed a complete solution.”
Results
Brady’s holistic chiller plant design and installation were tremendously successful. As a result, the RTP company is realizing many benefits from the project-some expected, and others that have been pleasant surprises.
The primary goal of the project was to improve the reliability of the cooling system and meet the cooling load demand during the hot summer months. The Site Operations Manager clearly describes the outcome: “The summer of 2018 was our first summer operating with the new system. We were able to meet the cooling load demand at all times that summer with no problems. We thought we would be bumping up against the maximum capacity of the chilled water system during those hot months, but we were surprised to find we had extra capacity available even then.” During the first winter post-installation, the new system was also able to efficiently throttle back to meet the reduced cooling load, something the previous system was unable to do.
Cost savings was not a primary driver of the project, but the RTP company is happy to find they are indeed saving with the new system. They are enjoying energy savings of $110,750 per year thanks to chiller and pumping efficiencies of the new system. The fact that they no longer need to make costly repairs to failing equipment also saves money and reduces worry. Finally, Brady’s design approach and upfront planning delivered substantial cost savings by avoiding other more costly options:
- Replacement of secondary chilled water pumps with new 100 HP models estimated at $305,000 and upsizing of associated
- electrical infrastructure estimated at $115,000 was avoided.
- Extremely disruptive and costly installation of larger 16″ secondary chilled water piping estimated at $230,000 was avoided.
- Installation of the new chillers and primary chilled water pumps without a plant shutdown
- or rental chiller saved at least $150,000 in rental equipment costs.
- No change orders were needed during the project thanks to Brady’s accurate design plan and budget. When the customer requested additional services, Building Clarity prepared a budget for the additional work and implemented it in a timely fashion with no impact to the overall project schedule.
Brady maintained their project schedule, which surprised many of the facilities staff based on their experience with other contractors. As the Site Operations Manager describes it, “I placed the schedule on the boiler room wall so our facilities staff could see what was to happen when. The operators were very skeptical that the schedule could be met, but Brady kept to the schedule throughout the project, which is unusual with most construction jobs.” By maintaining the schedule, Brady ensured that the new chillers and pumps were up and running before the high load summer months arrived, and the design’s workflow ensured there was no down-time during installation.