A new chilling station is providing reliable, efficient service to the medical district at the University of Texas at Austin.
A leader in academic medicine, the University of Texas at Austin is raising its standards by building the first medical school in nearly 50 years from the ground up at a top-tier U.S. research university — and it was in need of the right infrastructure for flawless operation.
In November 2012, the community voted on and approved a bond for a new medical district at the southeastern corner of campus, the site of the Dell Medical School, set to welcome students in June 2016. Forward-thinking in its approach to medical education, care and research in collaborative work spaces, the school now is served by one of the most efficient heating and cooling systems in the country.
To meet demands of a growing university, the team of Flintco and Burns & McDonnell was called in to design and build a new chilling station that would take its energy efficiency and heating/cooling distribution to the next level, an important aspect in efficiently running a level 1 trauma center.
In addition to the new Chilling Station No. 7 (CS7), Phase I also includes the $295 million, 500,000-square-foot Dell Seton Medical Center teaching hospital, the new level 1 trauma center serving the community’s underprivileged population — scheduled to open early 2017 — as well as other education and research buildings. The first phase accounts for 1.1 million additional square feet, which is approximately $800 million of new construction within two city blocks.
With the addition of the medical district, the cause of such a big load increase, the overall system will have gained substantial efficiencies due to the high performance of the CS7, says Jeff Easton, an engineer and certified energy manager at Burns & McDonnell. In numeric terms, this means 4,500 tons of cooling and 54 MMBtu of heating hot water.
Located on the outskirts of campus, the 15,000-ton CS7 houses the primary heating plant, heat pump chiller and three 85 percent-efficient water-tube boilers, while a new 5.5 million-gallon thermal energy storage tank sits right outside. Other upgrades include direct access to the steam-fired heating plant that was strategically embedded within the medical district for backup. To alleviate pressure-balancing issues between multiple plants in various chilling stations, CS7 will be controlled on a flow setpoint and was intentionally designed with more capacity steps: six 2,500-ton units, which ultimately will make it the most efficient plant on campus.
“Chilling Station No. 7 simulations anticipate a total plant annual efficiency of 0.55 kW/ton, which will further improve on the university’s exceptionally high energy performance,” Easton says. “Considering that the performance estimate includes the heat pump chiller input energy, CS7 will also contribute an estimated 75,000 MMBtu of ‘free’ heating. It is projected to be the university’s most efficient plant.”
Working in conjunction with the university’s existing chilling stations, CS7 is anticipated to be up and running by June 2016.
Check the Tank
The thermal energy storage (TES) tank, the second tank in the campus system, will provide an estimated 52,000 ton-hours of storage and allow nearly 10,000 tons of chilled water-producing equipment to shut down during peak hours of the day and recharge at night during off-peak hours, which saves money and energy. The main advantage of the TES tank capacity is to gain better control of the university’s demand-side load, which helps optimize its combined heat and power (CHP) system and microgrid, Easton says. The savings are a byproduct of that important capability.
The tank provides flexible chilled-water capacity that can be deployed to cover any equipment outages. With both tanks, the university can wield, shift, offset and control up to 10 MW of electric load, a powerful tool for any large campus.
Let It (Efficiently) Flow
Another substantial energy-efficient decision was the addition of the heat pump chiller, which will simultaneously provide hot and chilled water to the new district.
With a universal perspective, Burns & McDonnell engineers proactively coordinated with the building designers to make sure all appropriate heat exchangers were installed to match the pump’s capabilities. The heat pump chiller is intended to run year-round to maximize its return on investment, with a rated Coefficient of Performance (COP) of 6.0 and an annual savings goal of $177,000. As the campus grows, more heat pumps will be added for optimal efficiency. During the colder months when higher temps are needed, water-tube boilers are ready to heat water up to 180 degrees Fahrenheit.
"The heat pump chiller and boilers are arranged in a series configuration within a robust variable primary-variable secondary pumping scheme that provides stable flow delivery to the campus while allowing for pump energy savings and operational flexibility within the plant,” Easton says.
With water at a premium — both in price and available quantity — four independent water sources are piped to the new chilling station, which also has its own recovery system. The first source will provide recovered water from campus, which would ultimately be discarded anyway; the second is reclaimed water from the city; and the third and fourth deployments are domestic water from the city and university that will only be used as backups to the first two sources.
After numerous studies, the university developed a water treatment plan and started using reclaimed water in May 2013. By using 80 million gallons of reclaimed water, the goal is to save nearly $300,000 annually.
A programmable logic controller (PLC) system was designed to operate automatically with zero permanent staff on-site. High-tech cameras with zooming capabilities will act as security for the grounds and also allow operations staff to view pipe gauges and visually check for potential leaks.
Building on its existing control network, three more PLCs will be added for the CS7 and one more for the hot water plant. Since the campus is tied into the dedicated campus control network, the university’s system will be more robust than most. All will be remotely operable from Chilling Station No. 6.
For more information, contact Jeff Easton, 817-908-3009.
What Is a Chilling Station?
“The whole point of a chilling station is to make water cold, but we’re doing it on a very large scale — about 30,000 gallons per minute,” says Jeff Easton of Burns & McDonnell.