Energy Audit Method for University of Texas Campus Chilled Water Consumption

Photo of Amanda Garcia, Prasad Joshi, John Wangel Students: Amanda Garcia, Prasad Joshi, John Wangel

Sponsor: University of Texas Utilities and Energy Management

Date: Fall 2010

Requirements:
All calculations for this project must be done in Microsoft Excel. During an audit, no service interrupts can occur. In addition, the audit must utilize current instrumentation and existing tools to minimize costs. The audit should be easy to use with straight-forward and clear instructions, and should be adaptable to any campus building.

Problem:
The University of Texas Utilities and Energy Management Department generates power and provides chilled water to campus. The chilling stations on campus were designed to operate most efficiently at a chilled water temperature difference of 15 °F; however, the annual average chilled water temperature difference on campus is currently only 10.7 °F. The objective of this project was to design an adaptable energy audit plan for main campus buildings that will evaluate chilled water usage and provide options to improve each building's chilled water temperature differential.

Solution:
The team developed an energy audit that is completed in multiple phases. The audit was tested by the team at the Frank Erwin Center and Welch Hall because their differential temperatures were well below the chilling station design temperature. After selecting a building, the next step was acquiring general building information, including year built, important building personnel, and square footage. The next step is to perform the initial chilled water screening. For this step, the auditor collects an inventory of the equipment involved in the chilled water system and assesses the feasibility of the actual energy audit. We included this step because we found that the audit was not feasible for Welch Hall due to difficulties we encountered such as asbestos insulation, metal shielding, and broken gauges. During the execution of the energy audit, the conductor collects measurements of the flow rate, pressure, and temperature across the variety of equipment involved in the chilled water system using set of handouts we developed. The auditor can then input this data into a template to calculate wasted money, power, and carbon dioxide emissions at the power plant resulting from poor usage of chilled water. For the Frank Erwin Center, we predict annual savings of up to $9,400 and 165,250 pounds of carbon dioxide emissions. We recommend that The air handling units causing this waste should have control valves installed to reduce their waste and increase the sustainability of their operation.

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