Asumag 484 201106 Streching Dollars

Stretching Energy Dollars for Healthy Schools

June 1, 2011
Monitoring energy through chiller plant optimization.

When financial savings are critical to every institution, facility managers demand even more from their energy systems while looking to spend less. One way to achieve significant energy savings and healthy schools without making a substantial capital investment is through energy monitoring and chiller plant optimization.

The greatest energy savings available to school and university campuses can be generated from a facility’s existing chiller plant operation, where even small tweaks can result in significant improvements. Web-based monitoring systems can be an effective tool for analyzing large chiller plants and district cooling systems. Built on open standards, they offer networked solutions that collect and format data in real time and defined timeframe increments; monitor operations and equipment errors; and deliver oversight via Web-based alerts and alarms. Based on the information generated, engineers are able to track performance and remedy any malfunction in order to optimize energy efficiencies.

Critical Analysis

The monitoring process starts with an initial analysis of chiller plant operations. In most cases, industrial measurement devices are installed and existing equipment tested for accuracy. The data from the various systems are pulled together in one platform and routed to an automation system, then pushed to the Web every five minutes via ftp; most automation systems that are Web-based have the ability to do this very easily. Once accurate data are collected, an evaluation is done to understand how all the chiller components are working and determine the most efficient method of operating the plant.

By analyzing chiller operations, monitoring engineers are able to establish a matrix that selects the most efficient/cost-effective chiller configuration as a facility’s cooling load increases. Optimization steps might include redoing the sequencing of cooling towers, balancing the amount of energy consumed by different pieces of equipment, and enabling chilled water to be generated at the best efficiency and lowest cost. Facility managers can achieve cost savings by calibrating temperature sensors and the building automation system, eliminating inefficiencies in heat-exchanger performance, lowering condenser temperatures, and ensuring that flow through the plant and chillers meets the design tonnages recommended by equipment manufacturers.

Once the initial reconfigurations have been carried out, the Web interface enables continuous remote monitoring of a plant to maintain optimum operation. Monthly reports are submitted to the institution’s operating team to show actual savings from the enhanced operating strategies and to suggest additional system improvements.

Monitoring-Based Commissioning

With new healthy schools, generating ongoing energy savings can be achieved through a comprehensive monitoring-based commissioning (MBCx) process to ensure that all building systems remain "in tune." It is common knowledge that buildings rarely perform as intended. That’s why MBCx is beginning to emerge as an important approach to keep buildings operating at maximum energy efficiency. Complementing other energy-savings strategies, it refers to the "soft" process of verifying performance and design intent and correcting deficiencies through a continuous Web-based monitoring program.

MBCx incorporates three components: permanent energy information systems and diagnostic tools at the whole-building and sub-system level; retro-commissioning based on the data this generates; and ongoing commissioning that ensures efficient building operations and measurement-based savings accounting. Traditional commissioning is a process designed to ensure that all building systems perform interactively according to the design intent and the facility’s operational needs. It involves the participation of an owner’s representative, architect and engineer of record, as well as independent third-party commissioning specialist. The commissioning specialist works with the entire project team to verify that design, construction and startup of all equipment results in a facility that is achieving the education institution’s stated project requirements upon initial occupancy.

Here’s where monitoring-based commissioning takes over. Even the most technologically sophisticated facilities will experience equipment variables that result in diminished energy efficiency. The reasons that buildings do not perform as planned might include poor control of chilled water distribution to air handlers, badly sequenced chiller operation, or poor VAV zone control. The ability to verify performance and design intent on a regular basis and immediately correct inefficiencies presents an effective way of keeping a building’s long-term energy use on track. This is especially significant in a campus setting, where utilities are system-critical and different buildings are run on multiple power sources with chiller plants that need to be integrated effectively.

Already there is plenty of anecdotal evidence showing the value of monitoring-based commissioning in identifying savings opportunities that otherwise would not have been found.

A recent study for the California Energy Commission by Lawrence Berkeley National Laboratory stated: "On a portfolio basis we find MBCx to be a highly cost-effective means of obtaining significant portfolio/program-level energy savings across a variety of building types. MBCx helped identify a very wide range of deficiencies. Anecdotal evidence shows the value of monitoring in identifying savings opportunities that would not otherwise have been identified."

For education institutions looking to get a better handle on energy costs in existing buildings or seeking to maximize their investment in sophisticated chiller equipment and building automation system technologies in new facilities, remote energy monitoring offers a cost-effective means of realizing greater energy efficiencies and lowering operating costs over the life cycle of a building. Monitoring offers an important risk-management strategy that leads to verifiable and durable energy-demand reductions for any education facility.

Sidebar: Case in Point

Texas Woman’s University (TWU), Denton, has a central utility plant (CUP) that supplies steam and chilled water to the majority of the campus buildings. Ron Tarbutton, director of the physical plant at TWU, was concerned that the CUP was operating in a sub-optimized zone. He knew that dramatic improvements could be made to its efficiency, but was unsure of the cost of installing a monitoring system or the estimated return on investment for implementing the process variables that would enable the plan to achieve peak operating efficiency.

“Our goal in looking at a monitoring system was to reduce energy consumption and operating costs,” says Tarbutton. “We needed to identify design aspects that could be improved through operational and physical changes to the system and also wanted to train existing TWU staff on how to maintain peak operating efficiency.”

Tarbutton hired a mechanical service company to conduct a detailed survey of CUP operations to help understand current operating practices, plant layout and configuration, and to identify opportunities to maximize energy efficiencies. A time-shared, Web-based data collection and analysis system was installed to measure, present and analyze key facility indicators for plant optimization.

With an initial upfront cost of $75,000, the monitoring system enabled TWU to realize an annual energy savings of $96,000. The online energy dashboard shows “real time” impact of system operation on energy costs and provides 24/7 monitoring of the chilled water plant to maximize performance. Several potential retrofits have been identified that will enable the school to further increase savings and smooth operations.

Angerame is director of business development for Utilivisor, New York City. He can be reached at [email protected].

Related Stories

Sponsored Recommendations

Schedule an AIA Course Presentation

Get closer to completing your annual AIA Continuing Education requirement.. Our continuing education courses will get you that much closer to completi…