Browsing by Author "Joo, I. S."
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Item Application of Innovative Technologies During Continuous Commissioning(Energy Systems Laboratory (http://esl.tamu.edu), 2003) Joo, I. S.; Liu, M.; Wang, J.; Hansen, K.This paper demonstrates the implementation of new innovative technologies during continuous commissioning practices to improve building operations and reduce energy costs. A 30-year-old typical commercial building with a floor area of about 49,436 square feet was used as a case study building. The new technologies are a variable speed drive volumetric tracking method for building pressure control, a recently developed fan airflow measurement method for duct static pressure reset, and a new operational strategy based on the current variable chilled water flow technology. The results showed that these technologies improve building operation and maintenance and significantly reduce energy costs. The building energy consumption has been reduced by 48% based on monthly utility bills, of which 32% are contributed to the Continuous Commissioning savings.Item Continuous Commissioning of Public Schools(Texas A&M University (http://www.tamu.edu), 2007) Joo, I. S.; Turner, W. D.; Song, L.; Dong, D.; Baltazar-Cervantes, J. C.; Napper, G.; Wei, G.; Dallas, Texas; Bes-Tech Inc.Continuous Commissioning (CC) is a proven, highly cost-effective process that can improve building comfort and reduce energy consumption. This paper discusses the CC of three public schools in Austin, Texas. These schools include one high school and two elementary schools, one of which also includes a community center. Major CC measures implemented include resetting supply air temperature, duct static pressure, chilled and hot water loop ?P setpoints, condenser water temperature, and reheat water temperature; optimizing economizer operation and heat recovery unit operation; improving equipment scheduling and staging sequence; and adjusting terminal box air flow settings. Also included are some minor retrofits that convert a few constant volume units to variable air volume units and adjusting the fan pulleys for units that are oversized. Even though all three schools are well maintained, the CC project was able to achieve 10-14% energy reduction, which amounts to an annual cost saving of $80,000. With a total implementation cost of approximately $201,800, the simple payback is about 2.5 years.Item Demand-based Optimal Control to Save Energy: A Case-Study in a Medical Center(Energy Systems Laboratory, 2008-12) Joo, I. S.; Song, L.; Liu, M.; Carico, M.Continuous Commissioning®1 (CC®) strategies include reducing simultaneous heating and cooling, scheduling the facility’s occupancy needs, utilizing free cooling, and minimizing excessive supply air and outside air. Most significantly, this demand based control energy conservation strategy can facilitate mechanical system performance at near optimal conditions through the gradual advancement of control systems and the ability of upstream systems reading the status of downstream systems. This paper demonstrates demand-based temperature, pressure and economizer control by the mathematical optimization methodology illustrated by a case-study, implemented with actual systems in a 1.2 million square foot medical center. Based on the optimization results, the facility saved over 5% total building electricity and over 10% gas consumption in a period of one year while improving thermal comfort.Item Development of In-Situ Fan Curve Measurement with One Airflow Measurement(Energy Systems Laboratory (http://esl.tamu.edu), 2003) Liu, G.; Joo, I. S.; Song, L.; Liu, M.Fan airflow is the key parameter for air volume tracking control in variable air volume systems. One of the airflow measurement methods is to determine airflow using the fan speed, fan head, and fan curve. Both fan speed and fan head can be measured accurately. Therefore, the accuracy of the fan airflow depends on the accuracy of the fan curve. An experimental method has been developed to determine the in-situ fan curve with only one airflow measurement. This paper presents the theoretical background, experimental procedures, and verification results.Item Optimal Control in Three-deck Multi-Zone Air-Handling Units: A Case-Study(Energy Systems Laboratory, 2008-12) Joo, I. S.; Song, L.; Liu, M.; Douglas, B.A multi-zone air-handling unit was popular several decades ago due to the convenience of small sized modular units, which were inexpensive to install and easily maintained in a mechanical room. The cost and convenience proved to be of little benefit as the units perform poorly from an energy usage perspective. A “three-deck” multi-zone unit is a hybrid of its kind, and it can be very efficient when controlled properly. In theory, there will not be simultaneous heating and cooling if its heating damper is controlled separately from the control of the cooling damper. When the zone load is neutral (not heating or cooling), for example, all the mixed air will be bypassed through the bypass deck. However, there are opportunities and challenges in this system. This paper presents theoretical backgrounds of advantages and challenges in the system operation of the three-deck multi-zone unit and methods to optimize temperature and economizer control to improve energy efficiency. A case-study will be presented examining a medical facility’s utilization of 35 three-deck multi-zone units serving most hospital areas, as well as illustrates a 10% savings in total gas and electric consumptions over the period of one year.Item Performance Analysis of Dual-Fan, Dual-Duct Constant Volume Air-Handling Units(Energy Systems Laboratory (http://esl.tamu.edu), 2001) Joo, I. S.; Liu, M.Dual-fan, dual-duct air-handling units introduce outside air directly into the cooling duct and use two variable speed devices to independently maintain the static pressure of the hot and the cold air ducts. Analytical models have been developed to compare fan power and thermal energy consumption of dualfan, dual-duct constant volume air-handling units with single-fan, dual-duct constant volume airhandling units. This study shows that the dual-fan, dual-duct system uses less fan power and less thermal energy during winter, and uses more thermal energy during summer. Thermal energy performance can be significantly improved if the thermal energy penalty can be decreased or eliminated.Item Real-Time Forcast Model Analysis of Daily Average Building Load for a Thermal Storage System Control(Energy Systems Laboratory (http://esl.tamu.edu), 2009-11) Song, L.; Joo, I. S.; Guwana, S.Thermal storage systems were originally designed to shift the on-peak cooling production to off-peak cooling production to reduce the on-peak demand. Based on the current electricity charging structure, the reduction of both on-peak and off-peak demands is becoming an exceedingly important issue. Reduction of both on-peak and off-peak demands can also extend the life span and defer or eliminate the replacement of power transformers due to potential shortage of building power capacity with anticipated equipment load increases. The next day daily average electricity demand is a critical set point to operate chillers and associated pumps at the appropriate time. For this paper, a mathematic analysis was conducted for annual daily average cooling of a building and three real-time building load forecasting models were developed. They are first-order autogressive model, random walk model and linear regression model. Finally, the comparison of results show the random walk model provides the best forecast.