Browsing Published Articles by Issue Date
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Grubb, M. K.; Heffington, W. M. (Energy Systems Laboratory, Department of Mechanical Engineering, September 1988)[more][less]
Abstract: Texas A&M University's Energy Analysis and Diagnostic Center (EADC) performed 15 energy audits of small- to medium-size manufacturing plants during its first year. The purpose of the EADC is to identify and recommend specific opportunities to conserve energy. In addition, the EADC may identify and recommend opportunities to reduce operating costs, but which do not conserve any energy. The EADC accomplishes its mission through careful analysis of the relationship between the energy utilized and the operating characteristics of the plants. The EADC recommended 109 energy conservation opportunities (ECOs) in 15 energy audits, an average of seven ECOs per audit. The 109 recommendations are divided into four groups: Electrical Energy ECOs, Natural Gas ECOs, Non-Energy Saving ECOs, and Opportunity ECOs. This paper will briefly discuss the EADC method of energy auditing and reporting, the four groups of ECOs in detail, and the implementation of the ECOs.
URI: http://hdl.handle.net/1969.1/2182 Files in this item: 1
ESL-PA-88-09-03.pdf (2.743Mb) -
Haberl, J.; Jagannathan, V.; Lopez, R.; Sparks, R.; Kissock, K.; Willis, D.; Claridge, D. (IBPSA-USA (http://www.ibpsa.us), April 1991)[more][less]
Abstract: One of the inherent problems with monitoring hourly energy use and environmental conditions in commercial buildings is efficiently processing the "sea" of data that accumulates into an easily understood form. Even when the data exist, building energy analysts generally rely on multiple "flat" ASCII files for storing and retrieving their data only to find that it can take several hours to perform a simple task such as creating a 2-D time series plot of energy use using data from several monitored channels. Integrated data base structures such as relational data bases, if carefully designed, may offer some relief because they can provide the user with an easier access to the data that automatically keeps track of where data are and how to assemble them to satisfy a particular request. This paper presents a brief review of the different types of data required for a large building monitoring project, and the methods that have been developed for acquiring, archiving and retrieving data for the Texas LoanSTAR program, an eight year, $98.6 million revolving loan program for energy conservation retrofits in Texas state, local government and school buildings.
URI: http://hdl.handle.net/1969.1/94779 Files in this item: 1
ESL-PA-91-04-01.pdf (2.045Mb) -
Britton, A. J.; Heffington, W. M.; Nutter, D. W. (Energy Systems Laboratory, Department of Mechanical Engineering, March 1993)[more][less]
Abstract: A Department of Energy funded Energy Analysis and Diagnostic Center (EADC) has operated at Texas A&M University for six years. During the first five years of the center's operation, 135 audits were conducted and projects were recommended which would save $4 million annually (about 9 % of utility costs) for Texas manufacturers. Five projects discussed in this paper—repair air compressor leaks, install heat recovery equipment, correct power factor, install skylights, and tune-up boilers—recur often and have applicability to many plants in many industries. A simple method of measuring air compressor leak rates is covered. Decisions about power factor correction based on utility billing data can be made and those are discussed. The use of simple electronic analyzers to measure boiler combustion efficiency and tune boilers is possible, and higher cost projects such as use of skylights and recovery of heat from exhaust gases are also covered.
Description: The Department of Energy assists small and medium-sized industrial plants with no-cost energy surveys provided by twenty-three Energy Analysis and Diagnostic Centers (EADCs) around the U. S. The Texas A&M University EADC began in late 1986. During the first five years of operation, 135 audits were conducted and projects were recommended which would save $4 million annually (about 9 % of utility costs) for Texas manufacturers. Projects actually implemented realize just over half of the recommended earnings and the overall payback for implemented projects is slightly less than one year. Audits by the EADC are performed by students and staff of the Energy Systems Laboratory and Mechanical Engineering Department of Texas A&M University. Five important energy conservation opportunities (ECOs) are discussed in this paper with descriptions and at least one example. All five opportunities are common recommendations with significant energy and dollar savings, and simple paybacks less than four years.
URI: http://hdl.handle.net/1969.1/2474 Files in this item: 1
ESL-IE-93-03-17.pdf (4.543Mb) -
Sparks, R. J.; Campbell, S.; Kissock, J. K.; Haberl, J. S.; Belur, R. (Energy Systems Laboratory, Department of Mechanical Engineering, March 1993)[more][less]
Abstract: This paper explores some techniques which may help facility operators better understand complex hourly energy data by enhancing the display of data with animation (or timesequencing). Animated displays such as the ones presented in this paper enhance the usefulness of the graphic display because time and temperature dependent trends can be more easily seen. There is an increasing need for new display paradigms that can help facility operators efficiently scan and detect problems within the river of incoming data from control systems. This need becomes even more important during times of a shrinking labor pool. In this paper the use of animated displays are described as they apply to the measurement of chilled water where the animated display makes a faulty flow meter easier to diagnose.
URI: http://hdl.handle.net/1969.1/2472 Files in this item: 1
ESL-IE-93-03-36.pdf (3.676Mb) -
Haberl, J. S.; Claridge, D. E.; Kissock, J. K.; Reddy, T. A. (Energy Systems Laboratory, Department of Mechanical Engineering, March 1993)[more][less]
Abstract: While computer technology has vastly increased the quantity and quality of measured building energy use data, our ability to analyze the data has not kept step. As a result, building energy use data that could be used to identify operational and maintenance problems, determine retrofit savings, or point to new and innovative ways to reduce energy costs are routinely discarded. In this paper, we draw upon information system and data analysis theory to introduce EModel, a new tool for the analysis of building energy use data. EModel simplifies the previously laborious tasks of data browsing, reformatting and modeling through a user-friendly, Windows-based interface. Graphical, statistical, and residual analysis are performed with simple mouse clicks. Currently, EModel is used by the Texas LoanSTAR program to model pre and post-retrofit energy use so that retrofit savings can be determined. Its use to identify energy use models at a large institutional building is demonstrated.
URI: http://hdl.handle.net/1969.1/2475 Files in this item: 1
ESL-IE-93-03-33.pdf (3.251Mb) -
Boecker, C. L.; Bohmer, C.; O'Neal, D. L.; Bryant, J. (Energy Systems Laboratory, Department of Mechanical Engineering, March 1993)[more][less]
Abstract: Experiences with instrumentation, installation and maintenance of building energy metering systems are presented. The building energy metering is installed to support the Texas LoanSTAR program in sites throughout the State of Texas. Metering typically includes monitoring the whole building electric load, building thermal loads and selected submetered loads. The emphasis of the lessons learned is on the instrumentation used and installation problems encountered during this project.
Description: This paper is not meant to be only a discussion of instrumentation failures or problems. There are a number of "real world" problems that involve the installation of the instrumentation and maintenance. Other problems focus on proper communication between the installer and instrumentation manufacturer or between the installer and those who have to analyze the data. The presentation of the material is divided into three categories: (1) Equipment, (2) Installation, and (3) Maintenance.
URI: http://hdl.handle.net/1969.1/2473 Files in this item: 1
ESL-IE-93-03-34.pdf (5.201Mb) -
Dorhofer, F. J.; Heffington, W. M. (Energy Systems Laboratory, Department of Mechanical Engineering, April 1994)[more][less]
Abstract: The Energy Systems Laboratory (ESL) at Texas A&M University is currently monitoring the electrical energy use of a metal fabrication facility in Houston, Texas. This paper deals with the installation of the data acquisition system and subsequent analysis of 15-minute data. The data acquisition system has been used to justify energy conservation retrofits, increase productivity, and monitor plant activities. Projected future uses include quantifying savings from retrofits. Uses of the data and the resolution of early problems in dealing with the large amount of data generated each month will be discussed.
URI: http://hdl.handle.net/1969.1/2478 Files in this item: 1
ESL-IE-94-04-59.pdf (4.254Mb) -
Saman, N. F.; Johnson, H. (Energy Systems Laboratory, Department of Mechanical Engineering, April 1994)[more][less]
Abstract: A methodology for a psychrometric analysis of the problem of maintaining space temperature and humidity in the digital switch environment is presented. Such spaces produce minimum or no humidity generation. Several different humidification schemes, including isothermal (steam generation) and adiabatic (evaporative cooling) were analyzed. In some cases, the addition of a steam humidifier to an air handling system with an outside air economizer cycle was seen to require more energy than running the same system on minimal outside air with mechanical refrigeration and substantially lower moisture load. Because individual locations will have different operational parameters, this sort of analysis is done by the design engineer as a tool in selection and design of an appropriate humidification system.
Description: The intent of this paper is to outline a simple methodology to compute cooling and humidification loads at any location, using a variety of techniques for space conditioning. Application of the methodology for a given location will yield a comparative estimate for the amount of energy used for different space conditioning strategies. Although there are numerous building energy calculation methods ranging from simple degree-day procedures to comprehensive and computerized procedures which simulate building heat transfer and system/equipment performance, the Bin Method was chosen for this analysis. With this method, simplified manual calculations that account for the significant parameters affecting the energy usage in buildings are possible. Bin data is given in tabular form as the number of hours per year in which the ambient temperature falls in a given 5 degree window. Inasmuch as coincident wet bulb and specific humidity are given for each dry bulb window, the Bin Method further provides means of evaluating annual humidification loads. Using this technique, different cooling and humidification strategies for the space can be evaluated.
URI: http://hdl.handle.net/1969.1/2479 Files in this item: 1
ESL-IE-94-04-58.pdf (4.432Mb) -
Watt, J. B.; Haberl, J. S. (Energy Systems Laboratory, Department of Mechanical Engineering, April 1994)[more][less]
Abstract: Flow measurement is an important part of the analysis of building energy use whenever thermal energy use is being investigated. In a building flow measurements are typically required for the analysis of chilled water, hot water and steam condensate use. In applications where the accumulated or totalized energy use is needed microprocessor-based thermal energy meters, or Btu meters are often used to integrate and display flow and energy data or generate a totalized signal for input into a data acquisition system. In this paper new results from calibration efforts in the LoanSTAR program are presented, including the premature drop-out of magnetic-type tangential paddlewheel sensors, as well as several in-situ diagnostic measures for ascertaining whether or not a flow meter is experiencing turbulent conditions or if a flow sensor's output signal is suffering a degraded signal due to shaft wear.
Description: Flow measurement is an important part of the analysis of building energy use whenever thermal energy use is being investigated. In a building accurate liquid flow measurements are required for the analysis of chilled water, hot water and steam condensate use. Currently, in applications where the accumulated or totalized energy use is needed microprocessor-based thermal energy meters, or Btu meters are often used to integrate and display flow and energy data or generate a totalized signal that can be recorded by data acquisition system. The accuracy of totalized flow and energy measurements is directly effected by the quality of thermal and flow measurement devices.
URI: http://hdl.handle.net/1969.1/2476 Files in this item: 1
ESL-IE-94-04-57.pdf (5.236Mb) -
Saman, N. F.; Nutter, D. W. (Energy Systems Laboratory, Department of Mechanical Engineering, April 1994)[more][less]
Abstract: This paper discusses energy conservation projects in the area of industrial ventilation that have been recommended by the Texas A&M University Energy Analysis and Diagnostic Center (EADQ to small and medium-sized industries in Texas. The projects recommended include reducing blower operating time/speed and static pressure for dust collectors, installing radiation shield on ovens, and using outside air for cooling. The projects were recommended to different kinds of industries including wood fabrication, frozen food, primary metals, plastics and insulation products. These projects are predicted to save up to 8% of the plants' utility bills with average simple payback periods of less than three years. Projects that involved blowers (fans) speed/operation time reduction resulted in most savings.
Description: Industrial ventilation is key to providing a suitable working environment for employees and it assists in maintaining safety operation of different processes in an industrial facility. Usually, the emphasis is on designing a ventilation system that works properly. However, due to present and future increases in the costs of equipment and energy, it has become necessary to provide properly operating ventilation systems at reduced initial and running costs. In this paper three types of energy reduction projects that are related to industrial ventilation are discussed. They include reducing blower power, operating time/speed or filter pressure drop for dust collectors; using radiation shields on ovens; and using outside air for cooling process.
URI: http://hdl.handle.net/1969.1/2477 Files in this item: 1
ESL-IE-94-04-56.pdf (2.249Mb) -
Bou-Saada, T. E.; Haberl, J. S. (IBPSA-USA (http://www.ibpsa.us), August 1995)[more][less]
Abstract: In order to improve upon previous calibration techniques, this paper presents new calibration methods including a temperature bin analysis to improve hourly x-y scatter plots, a 24-hour weatherdaytype bin analysis to allow for the evaluation of hourly temperature and schedule dependent comparisons, and a 52-week bin analysis to facilitate the evaluation of long-term trends. In addition, architectural rendering is suggested as a means of verifying the building envelope dimensions and external shading placement. Several statistical methods are also reviewed to evaluate the goodness-offit including percent difference calculations, mean bias error (MBE), and the coefficient of variation of the root mean squared error (CV(RMSE)). The procedures are applied to a case study building located in Washington, D.C. Nine months of hourly whole-building electricity data and site-specific weather data were measured and used with the DOE- 2. ID building simulation program to test the new techniques. Use of the new calibration procedures were able to produce an hourly MBE of -0.7% and a CV(RMSE) of 23.1% which compare favorably with the most accurate hourly neural network models.
URI: http://hdl.handle.net/1969.1/94780 Files in this item: 1
ESL-PA-95-08-01.pdf (5.105Mb) -
Oh, J.; Haberl, J. S. (IPBSA-USA (http://www.ibpsa.us), September 1997)[more][less]
Abstract: The well-known versions of the sunpath diagrams that appear in the AIA's Architectural Graphics Standards are based on the equidistant sky dome projections and use a shading mask protractor developed by Olgyay and Olgyay at Princeton University in the 1950s. A designer using the AIA's Graphics Standards book, or other printed versions of the sunpath diagram, must select the nearest latitude, make photocopies of the appropriate sunpath diagram and shading mask protractor, and then overlay the shading mask protractor upon the diagram in the proper orientation. The outline of the shading device is then transcribed upon the shading mask, aligned at the proper orientation for the facade in which the window is being analyzed, and placed on top of the sunpath diagram to determine if a point centered at the base of the window is exposed to direct sunlight. Teaching this process to architects and engineers is tedious and error-prone since the students must calculate several angles and then mentally translate their cartesian coordinates onto a sperical coordinate system to determine whether or not their shading device is going to have the intended effect. As a result of this, the sunpath diagram and shading mask protractor are not widely used because many designers either do not understand how to use the tools or do not budget the time to analyze a shading device properly with these tools. This paper describes the new MS-Windows-based educational software package (Oh and Haberl 1996) that has been developed to fast-track the learning of the sunpath diagram and shading mask protractor which is based on previously published equations for plotting the sunpath diagram and shading mask protractor (McWatters and Haberl 1994a, 1994b, 1995). A review of the manual process is also provided to compare the computerized tool to the traditional design method.
URI: http://hdl.handle.net/1969.1/94778 Files in this item: 1
ESL-PA-97-09-01.pdf (3.757Mb) -
Zhou, J.; Deng, S.; Turner, W. D.; Liu, M. (Energy Systems Laboratory, Texas A&M University, May 2000)[more][less]
Abstract: The operation of a cogeneration power plant is complicated. The Energy Optimization Program (EOP, software made by SEGA, Inc.) was designed to simulate and optimize the operation of TAMU power plant. All major plant components were represented by appropriate models and then structured to establish a system model. A better understanding of the complicated interaction among all energy components within the plant was achieved through systematic simulation using EOP. Overall performance of the plant operation under different conditions was investigated. Further more, (online) operational optimization is made possible by load re-assignment according to EOP's calculation. Other researches on plant operation, such as the impact of utility rates on operational decision making, were also carried out with the help of this program. This paper shows how a well-designed commercial software is exploited in engineering research.
URI: http://hdl.handle.net/1969.1/2843 Files in this item: 1
ESL-PA-00-05-01.pdf (175.5Kb) -
Razinha, J. A.; Heffington, W. M. (Energy Systems Laboratory, Texas A&M University, May 2000)[more][less]
Abstract: The twenty-five most frequently suggested energy saving assessment recommendations in the Industrial Assessment Center program national database were examined using linear regression techniques to correlate between energy savings and demand reduction, and implementation costs. Poor overall correlations indicate that direct prediction of savings from implementation costs is generally unfeasible, with a limited number of exceptions. Correlations for the twenty-five most frequently suggested Texas A&M University recommendations were better than those for the national dataset. The value of this procedure to speed assessments seems not worthwhile considering the poor correlations and the value of the calculations it would replace.
Description: The Industrial Assessment Center (IAC) program, funded by the Department of Energy (DOE), consists of faculty and student teams from 30 universities nationwide that perform industrial assessments of small and medium-size manufacturing firms. Program goals include providing university students with energy conservation learning experiences combined with service to private manufacturers. These assessments target energy and waste stream reduction opportunities, as well as productivity improvements. A typical assessment consists of utility use analysis, a site visit, and a written report that summarizes the plant’s energy use, production processes, and waste handling. The report will also contain several assessment recommendations (ARs) that are thorough analyses of specific energy or cost saving measures and include expected savings, implementation costs and simple financial analysis (payback).
URI: http://hdl.handle.net/1969.1/2496 Files in this item: 1
ESL-PA-00-04-01.pdf (104.1Kb) -
Baltazar-Cervantes, J. C.; Claridge, D. E. (Energy System Laboratory, Texas A&M University, May 2002)[more][less]
Abstract: This paper presents seventeen approaches that use cubic splines and Fourier series for restoring short term missing data in time series of building energy use and weather data. The study is based on twenty samples of hourly data, each at least one year long. In order to differentiate the approaches, two comparisons were carried out. The first comparison was made between the estimated and actual values, as time series and as cross check plots. The second comparison is based on the fraction of the total data that can be estimated by and approach within specific ranges or error. Thus for the cooling and heating data, the fraction of the data set was estimated within 1%, 5%, and 10% of the measured values was determined. For the dew point and the dry-bulb temperature samples, the performance is based on the amount of data that are within 1, 3, 5, and 10ºF from the actual data. From the results of this analysis, it appears that linear interpolation is a better approach for filling gaps one to three hours long. The cubic splines approach gave better performance for gaps between four and six.
URI: http://hdl.handle.net/1969.1/2842 Files in this item: 1
ESL-PA-02-05-02.pdf (771.4Kb) -
Zhou, J.; Deng, S.; Claridge, D. E.; Haberl, J. S.; Turner, W. D. (Energy Systems Laboratory, Texas A&M University, May 2002)[more][less]
Abstract: Optimum economic operation in a large power plant can cut operating costs substantially. Individual plant equipment should be operated under conditions that are most favorable for maximizing its efficiency. It is widely accepted that boiler load significantly effects boiler efficiency. In the study reported here, the measured performance of a 300,000 lb/h steam boiler was found to show more dependence on ambient air temperature than on boiler load. It also showed an unexplained dependence on the month of the year that is comparable to the load dependence.
URI: http://hdl.handle.net/1969.1/2841 Files in this item: 1
ESL-PA-02-05-01.pdf (1.245Mb) -
Zhou, J.; Wei, G.; Giebler, T.; Turner, W. D. (Energy Systems Laboratory, Texas A&M University, October 2003)[more][less]
Abstract: The recent budget cuts campaign mandated by the governor’s office had all state agencies in Texas looking for ways to reduce revenue spending. One of the cost savings opportunities perceived by many university officials is to convert a typical 5-workday week into a 4-workday week (e.g., Monday to Thursday) with 10 working hours each day during the universities summer session. The potential savings come from the fact that the universities can be partially shut down during the prolonged weekends (Friday to Sunday). It is believed that the savings from partially shutting down an extra workday is much more significant than the marginal energy increase caused by the extended working hours during workdays
Description: This paper analyzes the potential energy cost savings of this approach for three real cases. The savings can be largely estimated by comparing whole-campus electricity consumptions between typical weekdays and weekends (or holidays). Energy overheads caused by the extended working hours (two more hours per working day) were also estimated. A limited shutdown scenario (similar to a typical weekend schedule) and a more aggressive shutdown scenario (similar to a typical holiday schedule) during the weekend periods are presented. The potential savings opportunities were from 0.32% to 1.53% of the annual electricity bills for different universities.
URI: http://hdl.handle.net/1969.1/2840 Files in this item: 1
ESL-PA-03-10-01.pdf (157.3Kb) -
Visitsak, S.; Haberl, J. S. (IBPSA-USA (http://www.ibpsa.us), August 2004)[more][less]
Abstract: This paper presents preliminary results of efforts to test the boundaries of the Givoni-Milne (G-M, 1979) bioclimatic design strategy chart, using DOE-2 simulations of a code-complaint single-story, slab-ongrade, single-family residence in selected climates. The analysis includes graphical and tabular presentations of the annual hourly simulations superimposed upon the G-M bioclimatic chart using weather data from selected climates.
URI: http://hdl.handle.net/1969.1/94774 Files in this item: 1
ESL-PA-04-08-03.pdf (1.600Mb) -
Rasisuttha, S.; Haberl, J. (IBPSA-USA (http://www.ibpsa.us), August 2004)[more][less]
Abstract: The paper reports on the results of research to reduce energy consumption in residential buildings in a hot and humid climate region (Thailand) using efficient architectural building components, energy efficient building systems, and renewable energy systems (solar energy) to produce electricity and heat domestic hot water. The solar energy system used in the analysis of the supplemental energy was a hybrid photovoltaicthermal (PV-T2) collector system, which is a combination photovoltaic (for producing electricity) and solar thermal collector (for producing hot water), and night-time radiator for radiating unwanted heat to the night sky. The research methods used in this work included instrumentation of a case study house, experimental data collected from an experimental PV-T2 collector system (Rasisuttha 2004), and calibrated building thermal simulation using DOE-2 (LBNL, 1982; 2000).
URI: http://hdl.handle.net/1969.1/94773 Files in this item: 1
ESL-PA-04-08-02.pdf (795.1Kb) -
Sung, Y. H.; Haberl, J. S. (IBPSA-USA (http://www.ibpsa.us), August 2004)[more][less]
Abstract: This paper reports on the development of a methodology to estimate energy use in a community and its associated effects on air pollution. This methodology would allow decision makers to predict the impacts of various energy conservation options and efficiency programs on air pollution reduction, which will help local governments and their residents understand how to reduce pollution and mange the information collection needed to accomplish this. This paper presents a broad overview of a community-wide energy use and NOx emissions inventory process and discusses detailed procedures used to calculate the residential sector's energy use and its associated NOx emissions. In an effort to better understand community-wide energy use and its associated NOx emissions, the City of College Station, Texas, was selected as a case study community to demonstrate the application of this methodology.
URI: http://hdl.handle.net/1969.1/2879 Files in this item: 1
ESL-PA-04-08-01.pdf (2.303Mb)
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