Challenges and Benefits of Digital Optimization for Chiller Plants


When building operators are under pressure to grow profits and increase energy efficiency, it can be easy to forget the human factor. The fact is, not all employees at central utility plants are going to be comfortable with digital optimization. Some may feel it’s a threat to their employment. Bearing this in mind, recognize that the introduction and installation of advanced digital solutions at central utility plants (CUPs) requires both technological expertise and attention to valued human resources.

The goal for CUP operators is to balance system performance and stringent environmental regulations with user comfort and ambitious sustainability goals. Driving down operational and equipment lifecycle costs is also important. Coupled with an ongoing workforce shortage, achieving these results increasingly requires a new approach.

When optimizing CUP operations, it’s important to not only look at equipment as standalone units, but also to understand how each component works together as a complete system. Even the most advanced equipment becomes inefficient when it’s not operating properly. A comprehensive energy analysis should be the first step in CUP optimization.


Discovery and Exploration Phases

Achieving an optimized CUP requires taking a holistic approach that encompasses the entire system, beyond chiller type and functionality. System designs must enable all relevant equipment to intelligently communicate with each other, as well as adjust to dynamic variables such as weather conditions, occupancy patterns and projected energy costs. By leveraging dynamic information sharing, CUP operators can make real-time decisions that drive down costs, increase reliability and advance sustainability goals.

An important part of the discovery process is mindset. Recognize that the people who operate the CUP have a shared knowledge of operations, various skill sets and pride in their ability. Ensure that operators feel they are still a necessary part of the process, and you’ll have buy-in from the team.

Scalability is one of the first factors to consider. Greater optimization is achieved when there are at least two or three fully functional chiller assets. Rarely will you see return on investment across the value stream with just one chiller asset. Digital optimization can be implemented for several chillers serving a single building to hundreds of chillers serving several blocks of buildings. A college campus or large healthcare campus, with 50 or 60 different types and sizes of buildings, are prime examples.

While the goal is to launch optimization throughout the entire CUP, taking a scaled approach allows operators to manage capital expenses while providing proof of performance.

Application of digital optimization solutions is applicable across all sectors in commercial, industrial and institutional applications. Some examples include healthcare, higher education, office buildings and manufacturing.

One advantage of digital optimization is that the system can determine which assets to operate – and at what capacity – at any time. It factors in utility rates, demand changes and ways to shed load during peak times. This saves money and increases energy efficiency.

Optimization can also automate the asset maintenance and diagnostic processes. If vibration on an asset is out of range, for example, it may be an early indicator of a need for service.

Existing assets must be inspected and evaluated for compatibility before any steps toward further digital optimization occur. One shortfall in existing systems can be that there may not be enough data points. Often, new sensors can be installed on top of existing equipment, then connected to the control panel of the central optimization control system. This new technology is easily integrated into existing building systems and is often complimented by the addition of another screen in the operator’s office so plant optimization activities can be monitored.

If replacement of chiller assets is required, the trend is toward new units with smaller footprints that are designed to reduce embodied carbon while also delivering higher operating efficiencies. This translates into more capacity, taking up less space in the mechanical room. Keep in mind the need for successful integration, overall energy efficiency and advancing strategies to move away from fossil fuels.

The benefits of central utility plant digital optimization (graphic from Johnson Controls). Click to enlarge.


Setting Digital Optimization in Motion

With new construction or major renovations, the project starts with field sales experts working directly as part of the construction team. Digital optimization is an integral part of the early planning stages. It ensures connectivity of all system components. As operators begin to reimagine CUP design, it’s important to maintain flexibility to accommodate future growth.

The ideal scenario starts with at least two to three chillers coupled with a highly variable load profile. In many comfort cooling situations, there can be a wide variation in load due to weather, occupancy, time of year and number of buildings occupied. Many systems are at highest efficiency when they are at full load or off. But in reality, variability in load demand and the resultant need to deliver part-load performance is the norm.

With several assets engaged – chillers for cooling, boilers for heating – it’s not uncommon to have multiple assets operating simultaneously. With optimization, you can move energy for maximum efficiency. For example, using heat pumps to repurpose the normally wasted heat energy from the chiller so the boiler doesn't have to engage improves efficiency three to five times.

Onsite thermal storage, whether chilled or hot water or both, can help manage loads to operate minimally during peak utility charge times. Operating assets to generate heat or cold to store when energy costs are low is becoming a popular strategy to achieve ideal optimization.

The YORK® CYK Water-to-Water Compound Centrifugal Heat Pump can help reduce water and operational costs by as much as 50% when compared to traditional boiler and chiller applications.


Collecting and Analyzing Data Points

Digital transformation is critical for enabling real-time data that optimizes central plant performance. Without this data, plant operators are at a disadvantage in predicting future states and backing decisions with proof points. But tracking and reporting data manually takes time – a resource many CUP operators don’t have. A typical chiller has over 100 components that can impact its efficiency. The average building automation system (BAS) is unable to accommodate these vast data points, much less analyze and interpret the data in a meaningful way.

Central plant optimization software empowers operators with advanced analytic and diagnostic technology. Smart sensors collect data from equipment and external inputs such as weather and utility pricing. Combined with unique parameters set by operational teams, the system creates a digital twin of the building that includes models of all equipment within the CUP. This is used to predict energy performance and costs under all operating variables.

Look for systems that use artificial intelligence and predictive algorithms. Data is gathered and analyzed continuously throughout operation to identify when equipment declines below peak performance, then it automatically adjusts to help regain maximum efficiency. Equipment health is monitored through fault detection and diagnostic (FDD) tools to identify performance drift or component malfunctions and maximize up-time. Factors such as weather forecasts, building schedules and historical trends are leveraged to predict hourly heating and cooling loads and optimize energy usage.

Data aggregation and monitoring should happen seamlessly with little required from facilities teams. If an issue requires extra attention, technicians can perform remote inspections, freeing up internal teams, or a notification can be sent directly to key personnel onsite.


Find the Right Partner for Digital Optimization

Beginning a CUP digital transformation requires strategic planning and consultation with an experienced partner. In a new facility, digital optimization is part of the initial design and construction cycle. For existing CUPs, however, implementation typically takes at least three to four months. Bear in mind that the system learns as time progresses, measuring current use and future predictions against historical data. Continued refinement should yield increasing benefits.

A robust optimization system will provide copious data to demonstrate its value. Typical ROI is less than five years.

Using a combination of predictive analysis and historical information helps companies make sound decisions relating to CUP operations. Ever-changing loads, weather and utility prices combine with hundreds of components that all impact energy efficiency. While previous strategies focused on individualized equipment efficiency and automation, CUP optimization considers the complete system. With this strategy, intelligent data collection and predictive algorithms monitor and adjust CUP performance while empowering plant operators to make informed decisions.


All images courtesy of Johnson Controls.

About the Author

Kiran Waghmare, Global Product Manager, Johnson Controls, earned his Mech. Eng. degree in 2010 and his MEng. in thermal engineering in 2013, both from the Indian Institute of Technology in Bombay, India. After graduation, he worked in the HVAC industry for five years as a product engineer before joining Johnson Controls’ team in 2019. His first three years with Johnson Controls he applied his skills as an applications engineer, focusing on air- and water-cooled chillers, before moving to product management.

About Johnson Controls

From its head office in Cork, Ireland, Johnson Controls offers the world’s largest portfolio of building technology, software and services. Supported by a team of more than 100,000 dedicated employees working across 150 countries, it helps customers achieve sustainability goals and power their missions. Johnson Controls’ mission is to provide customers with the most sustainable central plant systems, starting from the most basic equipment to the highly technical control systems that help it all operate most efficiently. Its U.S. headquarters is in Milwaukee, Wisconsin, while much of its chiller operations are in York, Pennsylvania. For more information, visit


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