Green Cooling: Improving Chiller Efficiency
This new chiller simulation module being developed by Building Performance Assurance Project members will help building managers compare optimal and actual chiller efficiency.
Chillers are the single largest energy consumers in commercial buildings. These machines create peaks in electric power consumption, typically during summer afternoons. In fact, 23% of electricity generation is associated with powering chillers that use CFCs and HCFCs, ozone-depleting refrigerants. Satisfying the peak demand caused by chillers forces utilities to build new power plants. However, because chiller plants run the most when the weather is hot and very little at other times, their load factors - and hence the utilities' load factors (the percentage of time the power plant is generating electricity) - are low. Thus, to utilities, chillers are more costly to serve than other loads.
The phase-out of CFC refrigerants, intended to protect the ozone layer under an international agreement, has triggered an unprecedented wave of chiller replacements that will accelerate during the next 10 years. Energy-efficiency measures implemented in conjunction with chiller retrofits can reduce the load and therefore the required chiller size, making the change more economical overall. But once the chiller is replaced, the opportunity for an integrated approach is lost. Most chiller plants are oversized, and even those that are correctly sized operate most of the time at low part-load efficiencies. New technologies such as direct digital controls and variable frequency drives, combined with improved design, commissioning, and operation, can decrease chiller plant energy consumption by more than 50% while improving their reliability and helping the environment.
Chiller projects in which the Center participates include:
- DOE's In-House Energy Management Integrated Chiller Retrofit Program.
- The Department of Energy anticipates a need for more than $200 million in chiller upgrades in response to aging cooling plants and the phase-out of CFCs. Direct line-item Congressional funding for these projects is unlikely. Integrating energy-efficiency measures (load reduction) with chiller upgrades and correctly sizing the chillers can increase a project's cost-effectiveness and may allow DOE facilities to fund their own retrofits through innovative energy savings performance contracts. The LBNL Applications Team (CBS News, Fall 1994, p.1) is developing an implementation guide and sample documents to facilitate such contracts. We will also specify a chiller plant monitoring tool kit to help facility managers determine the load for optimum sizing and system configuring and to establish the baseline under an energy savings performance contract.
- The Building Performance Assurance Project.
- The goal of this effort is to improve building performance by creating building life-cycle information systems (CBS News, Summer 1995, p.1). Much of the first year's work focused on developing computerized commissioning tools and performance tracking of chiller plants. The Center's three programs (Building Technologies, Energy Analysis, and Indoor Environment) and LBNL's Computing Division are involved in this effort. Project participants are now integrating chiller plant design, commissioning, performance tracking, and operations and maintenance tools into a single computing environment. Laboratory Directed Research and Development support funds this project.
- The Remote Building Monitoring Project.
- Now in its first year, this project is focused on monitoring and tracking chiller performance over the Internet. The second-year goal is to include control for optimization under real-time pricing. In subsequent years, the project will expand control and diagnostic capability and integrate other building systems.
- Energy audit of the U.S. Embassy in India.
- This project began when Secretary of Energy Hazel O'Leary and the Ambassador to India signed an agreement to upgrade the energy efficiency of American embassy facilities in New Delhi and to make the embassy a showcase of American technology. Applications Team member Brad Gustafson, who is based in Washington, D.C., at the Federal Energy Management Program, joined representatives of the State Department and a private company in auditing about 37,000m2 (400,000 ft2) of embassy facilities, including the ambassador's residence, office space and support areas, and a U.S. Information Services building separate from the embassy grounds. The team recommended short-term improvements and long-term chiller upgrades, and provided information to help embassy staff evaluate requests for proposals for an energy savings performance contract.
- The CIEE Building Diagnostics Program.
- With funding from the California Institute for Energy Efficiency, a multi-institution team is examining chiller plant failure mode analysis and evaluating techniques for detecting and diagnosing the failure modes. One objective of this work is to develop a knowledge-based system to help diagnose chiller failures and devise strategies to correct the problems. Advanced data visualization will play a major role in the diagnostics project.
The Center's researchers and Applications Team members are working on other projects involving chiller efficiency upgrades, monitoring, and verification and developing innovative ways to determine and optimize chiller plant performance. The projects in which the A-Team is participating are here. Thanks to these many efforts, LBNL's "center of exellence" in chiller plant efficiency will help ease the phase-out of CFC refrigerants and the transition to better chillers. Not only have chiller manufacturers introduced more efficient products than the machines they will replace, there are considerable opportunities to improve chiller plant design, system integration, and operations as well. LBNL's work in developing advanced tools for design, performance monitoring, commissioning, diagnostics, and control and innovative financing of energy-efficient chiller projects will help capture some of the savings through new technology.
Applications Team Leader
(510) 486-5988; (510) 486-5394 fax
Center for Building Science
and Public Information Division
(510) 486-4210; (510) 486-5394 fax
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