At Lab Facility, Chilled Water Plant Improvements Boost Energy Efficiency, Maintain Required Environment

A state mandate along with an internal commitment to reduce energy consumption spurred a chiller plant optimization project at Maryland's Institute for Bioscience and Biotechnology Research.

By James Johnson and Jonathan Kosobucki, P.E.

The Institute for Bioscience and Biotechnology Research (IBBR) in Rockville, MD connects scientists from the University of Maryland, the National Institute of Standards and Technology, and industry to find solutions to scientific and medical challenges such as new vaccines and the development of diagnostic and therapeutic products. With one of the nation’s largest collections of high resolution instruments, they look inside cells and manipulate molecules. IBBR researchers have figured out the molecular structure of proteins, unraveled the protein interactions involved in autoimmune disorders, and discovered possible countermeasures for antibiotic resistance.

chiller plant optimization
At the Institute for Bioscience and Biotechnology Research, chiller plant changes contribute to energy efficiency improvement.

Their work is precise and infinitesimal, and experiments do not end simply because the clock says 5 p.m. or there’s a sweltering heat wave. IBBR scientists require around-the-clock access to their labs — and those labs require a stable environment. A change in room temperature of just one or two degrees could impact the outcome of an experiment; increased humidity could interfere with the sensitive scientific measurement equipment.

With high energy use equipment, an HVAC system that must run day and night, and buildings that never go dark, IBBR was one of the biggest energy hogs on the University of Maryland campus as well as one of the most difficult to make more energy efficient. But, challenged by a state mandate to reduce energy consumption and a university commitment to reduce total energy consumption 20% by 2020, the IBBR facility management team embarked on an aggressive plan to meet this goal. One of the first actions: a chiller plant optimization project that achieved substantial savings.

When the project began, the plant was consuming energy at 0.9 kW/ton and operating at just 50% output. Now, the plant runs 27% to 37% more efficiently — effectively keeping energy costs flat while building occupancy increased. IBBR has also reduced CO2 emissions by about 125 tons per year and improved plant reliability, so that the lab environment remains stable, even through icy, snowy winters and hot, humid summers.

Two Buildings, One Plant Optimization

The IBBR campuses, part of the University System of Maryland, occupy over 200,000 square feet of lab and office space in Rockville. The original building opened in 1989, and a wing was added in 1995, for a building total of 75,000 square feet. Each wing has separate chilled water plant and hot water systems and mechanical systems, built to size for the original construction. The systems were connected when the new wing was built, but the components remain segregated. This allows the systems to operate as though they are a single plant, with built-in redundancy. Building 2, built in 2007, is a 126,000 square foot facility that also has a chiller plant and a steam-heating plant.

chiller plant optimization
James Johnson, director of facilities and lab services, IBBR, Rockville, MD

Combined, the entire system — the IBBR’s environmental stabilization plant — maintains the lab environment by conditioning and controlling the temperature, humidity, and quantity of air flowing to and through the labs in each building with large, 100% ventilation air handling units and a combination of variable and constant volume terminal units. A Siemens Apogee building automation system controls and monitors the plant.

Facilities staff tackled out easier projects first. They took steps to conserve water, which IBBR was using at a rate of one million gallons a month. They attacked the lighting, which consumes 20% of the lab’s energy, and reduced the number of fixtures installed throughout the labs. Then the real work began. Because the HVAC system accounts for as much as 70% of the lab’s energy use, they first turned their attention to optimizing the 900-ton chiller plant in Building 2.

Although it was just five years old when IBBR launched its project, Building 2 turned out to be the better candidate for HVAC optimization. Its 900-ton plant has two 450-ton electric centrifugal water chillers, two condenser water pumps, two cooling tower cells, two primary pumps, and two secondary pumps.

It was originally outfitted with several variable speed pumps, but the primary chill water and condensing pump ran at a constant volume, the cooler towers were configured to maintain a consistent speed, and water temperature was controlled with a cooling tower bypass valve — these were prime targets for efficiency measures.

The chillers were manufactured at the same time, but one of them had never run as efficiently as the other and had ongoing problems with surging. The plant has to provide 3,800 hours of cooling every year, so the facilities staff started their review of individual plant components with the chillers. They found that optimizing each component separately could significantly increase the plant’s overall efficiency, allowing it to operate at the lowest possible kW/ton without degrading the atmosphere of the labs.

The Solution: A System Built On Relational Algorithms

IBBR chose Optimum Energy’s OptiCx™ HVAC optimization platform with OptimumLOOP™ control software for chilled water systems. It offered several advantages: it used much of the existing plant equipment, a dedicated Optimum engineer oversee implementation and consult on best practices, and the solution “self learns” the most efficient operating conditions of each component, then uses that intelligence to optimize the entire plant. From the variable speed drives and sensors installed on chillers, pumps, valves, and tower fans, the OptimumLOOP software collects a tremendous amount of data about the plant equipment, including water flow, electrical power consumption, and load conditions. It compares the data to control algorithms, assesses plant conditions in real time, and then automatically changes pump and fan speeds, leaving chilled water temperature, equipment staging, and other operational changes to maximize efficiency.

IBBR began deploying the solution in 2013, after completing the university’s procurement process and getting some funding from the local energy provider. The first step was installing some new variable drives to convert IBBR into an all-variable-flow plant, as well as the sensors on each plant component.

Next came connecting OptimumLOOP with the Siemens building automation system and upgrading the building automation system network in Building 2 to Ethernet to ensure the data flow wouldn’t challenge the local network capacity. When that was finished, IBBR had OptimumLOOP up and running across the chiller plant — just in time for the cooling season of 2014.

Tracking Energy Efficiency

In the first year of full operation, the optimized plant cut the IBBR’s energy use by an average of 30%. Originally, each primary chilled water pump ran consistently at 60 Hz. Now they each run at an average of 55 Hz. By itself, that may not appear to deliver huge savings, but the change in speed provides about 20% savings for these pumps alone. And OptimumLOOP’s relational control algorithms maximize overall plant performance and meet the optimal parameters for current conditions. IBBR found that running individual pieces of equipment at more efficient speeds adds up to one big number.

2014 was a year of testing and tuning. For instance, in trying to protect itself from surging, the chiller control panel ended up hampering energy efficient operation. The chief problem was old data: working with Optimum engineers, the IBBR facilities team urged chiller mechanics to update the data at the control panel, and Siemens engineers adjusted the chiller code in their system to address condensing water control issues.

In addition, the greater visibility into plant operations provided by OptimumLOOP’s connection to the BAS revealed unusually poor plant efficiency — at one point it was operating at a kW/ton rate 10 times higher than expected. That had to be incorrect, but the kW values coming back from the plant all appeared to be within expected ranges, and supply and return temperatures were also normal and verified. The problem turned out to be the flow meter, which was repaired and reinstalled.

Plant efficiency got progressively better over the course of the year. During 2015, there was consistent energy reduction, and the plant was running in an optimized mode almost all the time, adapting and responding to real-time loads and changing ambient conditions. By the end of summer 2016, IBBR had wrung all possible efficiencies out of the environmental stabilization plant, and it is now fully optimized.

Beating the University Energy Mandate

From the beginning, the IBBR facilities team took the long view of the optimization project, in part because Building 2 was only at about 50% capacity when the work began. Now the labs are nearly fully occupied with scientists running their experiments daily — and that has been the true test. The optimized plant has been able to operate just as efficiently with a full load. IBBR’s energy consumption has remained flat even as user occupancy has nearly doubled.

For the IBBR facilities team, what really matters is that they supported the researchers throughout the optimization process. Now the HVAC system remains a behind the scenes hero. Scientists’ work goes on unimpeded, and their lab conditions have remained constant, consistent, and repeatable — precisely the best environment for fighting disease at the molecular level.

With the plant now running 30% more efficiently on average, IBBR is aggressively moving forward with bigger, more complex projects to cut energy consumption even further. Their goal? To help the University of Maryland beat its own climate targets.

chiller plant optimizationJohnson has served the University of Maryland’s Institute of Bioscience and Biotechnology Research since 2006, and became Director of Facilities and Lab Services in 2012. Responsible for the maintenance, repair and operational support of the research lab and office space, he continues to champion operating and maintenance practices and installation of systems and equipment that improve the reliability and efficiency of mechanical and HVAC systems. Formerly, he ran the Mechanical Services Division of Siemens Building Technologies’ Chesapeake District. Johnson trained as a nuclear plant operator with the U.S. Navy, where he served for 12 years.

chiller plant optimization

Kosobucki, a senior energy engineer with Optimum Energy, began his career designing MEP systems for new construction projects with WSP Flack + Kurtz (now WSP Parsons Brinckerhoff). He began focusing exclusively on energy reduction in 2012 and has spent more than a decade working on HVAC systems throughout North America, Europe, the Middle East and Asia. Kosobucki holds a master’s degree in mechanical engineering from Columbia University and is a licensed professional engineer.