Browsing ESL Theses and Dissertations by Title
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Analysis of improved fenestration for code-compliant residential buildings in hot and humid climatesMukhopadhyay, Jaya (Texas A&M University, August 2005)[more][less]
Abstract: This thesis presents an analysis of energy efficient residential windows in hot and humid climates. To accomplish this analysis, the use of accurate simulation tools such as DOE-2.1e is required, which incorporates the results from the WINDOW-5.2 simulation program to assess accurate fenestration performance. The thesis also investigates the use of optimal glazing types, which, for future applications, could be specified in the code to reduce annual net energy consumption to zero. Results show that combinations of low-E and double pane, clear-glazed windows, which are optimally shaded according to orientation are the best solution for lowering both annual energy consumption and peak electricity loads. The study also concludes that the method used to model fenestration in the simulation program plays an important role in accurately determining the effectiveness of the glazing option used. In this particular study, the use of the WINDOW-5.2 program is highly recommended especially for high performance windows (i.e., low-E glazing). Finally, a discussion on the incorporation of super high performance windows (i.e., super low-E, ultra low-E and dynamic / switchable glazing) into the IECC code concludes that these types of glazing strategies can reduce annual net energy use of the window to zero. Future work identified by this thesis includes a more extensive examination of the passive solar potential of high performance fenestration, and an examination of the appropriate methods for specifying these properties in future versions of the IECC code. This implies that future specifications for fenestration in the IECC code could aim for zero net annual energy consumption levels from residential fenestration.
Files in this item: 1etd-tamu-2005B-ARCH-Mukhopa.pdf (5.655Mb)
Analysis of Innovative HVAC System Technologies and Their Application for Office Buildings in Hot and Humid ClimatesTanskyi, Oleksandr (December 2010)[more][less]
Abstract: The commercial buildings sector in the United States used 18 percent (17.93 Quads) of the U.S. primary energy in 2006. Office buildings are the largest single energy consumption category in the commercial buildings sector of the United States with annual energy consumption around 1.1 Quads. Traditional approaches used in commercial building designs are not adequate to save energy in both depth and scale. One of the most effective ways to reduce energy consumption is to improve energy performance of HVAC systems. High-performance HVAC systems and components, as well as application of renewable energy sources, were surveyed for buildings in hot and humid climates. An analysis of performance and energy saving potential estimation for selected HVAC systems in hot and humid climates was developed based on energy consumption simulation models in DOE-2.1E. A calibrated energy consumption model of an existing office building located in the hot and humid climate conditions of Texas was developed. Based on this model, the energy saving potential of the building was estimated. In addition, energy consumption simulation models were developed for a new office building, including simulation of energy saving measures that could be achieved with further improvements of HVAC system above the energy conservation codes requirements. The theoretical minimum energy consumption level for the same office building was estimated for the purpose of evaluating the whole building energy efficiency level. The theoretical minimum energy consumption model of the office building was designed to provide the same level of comfort and services to the building occupants as provided in the actual building simulation model. Finally, the energy efficiency of the building that satisfies valid energy conservation codes and the building with an improved HVAC system was estimated based on theoretically minimum energy consumption level. The analysis provided herein can be used for new building practitioners and existing building owners to evaluate energy reduction potential and the performance of innovative technologies such as dedicated outdoor air system, displacement ventilation, improved cooling system efficiency, air source heat pumps and natural gas heat pumps.
Files in this item: 1TANSKYI-THESIS.pdf (4.678Mb)
An Analysis of Low Cost, Energy Efficient, Housing for Low-income Residents of How and Humid ClimatesKootin-Sanwu, Victor (Energy Systems Laboratory, May 2004)[more][less]
Abstract: The purpose of this research is to develop methods that will enable the reduction of owning and operating costs of low-income housing in the hot-humid climates of the U. S. The objectives include investigating various scenarios that will enable the implementation of cost-effective construction of low-income housing using volunteer labor. The research uses a case study approach where a base-line energy use is established using a comparative Princeton Score Keeping Method (PRISM) analysis and measurements from a case study house. A prototype house is then simulated with the DOE-2 building simulation program, and the energy savings calculated by comparing simulated energy and water conservation design measures (E&WCDMs) with the calibrated baseline energy simulation. The cost and maintenance of the house are analyzed with the real cost of construction of a case study house in Bryan/College Station, Texas.
Files in this item: 1ESL-TH-04-05-01.pdf (24.12Mb)
Nutter, Darin Wayne (December 1994)[more][less]
Abstract: The mass flow characteristics of flashing Refrigerant-22 from a small vessel were investigated. A flash boiling apparatus was designed and built. It was modeled after the flashing process encountered by the accumulator of air-source heat pump systems. Three small pyrex glass vessels were used to hold the refrigerant and allow for visualization studies of the flashing process. Baseline experiments were run varying initial pressure, initial refrigerant amount, orifice diameter, and vessel geometry. Three sets of experiments were run using two passive enhancement methods (the addition of steel balls and the addition of small amounts of oil) and one active enhancement method (the addition of an immersion heater). Furthermore, a lumped-parameter analytical model was developed from basic thermodynamic principles that predicted the rate of depressurization for the flashing refrigerant. The study showed that the initial refrigerant amount and the orifice size had the greatest influence on the mass flow and pressure characteristics during each sixty second test. The initial pressure and vessel volume had less of an impact under the conditions tested. Two of the enhancement methods consistently increased the amount of refrigerant flashed during the tests as compared to the baseline data for the same initial conditions. The addition a 1 cm layer of 3.6 mm steel balls to the base of the vessel increased the amount flashed from 21% to 81% and the addition of the 215-watt flat-spiral immersion heater the increased the amount flashed from 47% to 111 %. Foaming at the vapor-liquid interface was observed with the refrigerant-oil mixture experiments as two of the eight test conditions averaged an increase while six averaged a decrease, ranging from a 21% increase to a 27% decrease. The analytical depressurization model predicted general pressure and mass flux trends, and revisions to the model improved pressure predictions to within ±11%.
Files in this item: 1ESL-TH-94-12-05.pdf (4.956Mb)
Malhotra, Mini (Texas A&M University, December 2005)[more][less]
Abstract: Energy-efficient building design involves minimizing the energy use and optimizing the performance of individual systems and components of the building. The benefits of energyefficient design, in the residential sector, are direct and tangible, provided that design strategies with a substantial combined energy and cost-saving potential are adopted. Many studies have been performed to evaluate the energy-saving potential and the costeffectiveness of various design options, and to identify conditions for optimizing the performance of building systems and components. The results of these studies, published in various resources, were analyzed discretely using different techniques, and were reported using different bases for comparison. Considering the complex interaction of, and energy flows through various building components, it is difficult to directly compare/combine the results from various studies to determine the energy-saving potential of combination of strategies, and to select an appropriate set of strategies for making design decisions. Therefore, this thesis develops a comprehensive survey and analysis of energy-efficient design strategies and their energy-saving potential, in isolation as well as in combination, using a DOE-2 simulation model of a prototype house in the hot and humid climate of Houston, Texas. Optimized strategies that included building configuration, materials/ assembly for building envelop components, and efficient mechanical and electrical systems, equipment and appliances, were applied in combination that could minimize the annual energy use. Application of these strategies is expected to allow downsizing systems and equipment and to confirm their operation at their rated performance, resulting in additional installation and operation cost savings. The study is concluded by outlining the procedures for selecting optimized set of strategies, and by developing guidelines for achieving maximum energy-efficiency in singlefamily detached houses in hot and humid climates. Thus, this study will facilitate the selection of energy-saving measures for their individual or combined application for developing energyefficient residences in hot and humid climates.
Files in this item: 1etd-tamu-2005C-ARCH-Malhotra.pdf (1.937Mb)
Malhotra, Mini (December 2009)[more][less]
Abstract: This dissertation addresses the issues of climate change and depletion of non-renewable resources of energy and water, and aims at eliminating the use of non-renewable resources of energy and water for the building operation in single-family detached residences in the U.S. With this aim, this study investigated the feasibility of the off-grid, off-pipe design approach in six climate locations across the U.S. to achieve self-sufficiency in a house for building energy, indoor water use, and household wastewater and sewage disposal using only on-site available renewable resources. For the analysis, a 2,500 ft2, 2000/2001 International Energy Conservation Code standard reference house with typical building and usage characteristics was selected as the base case. The six U.S. climate locations included: Minneapolis, MN, Boulder, CO, Atlanta, GA, Houston, TX, Phoenix, AZ, and Los Angeles, CA. The renewable resources considered for this study included: solar radiation, wind, biomass for building energy needs; rainwater for indoor water use. In addition, the building site was considered for the disposal of household wastewater and sewage. The selected climate locations provided different scenarios in terms of base-case building energy needs and availability of renewable resources. Depending on these, energy and water efficiency measures were selected for reducing the building needs. For the reduced building needs, the sizing of systems for self-sufficiency was performed, including: solar thermal system for building’s space heating and water heating needs, photovoltaic and wind power systems for building’s electricity needs; rainwater harvesting system for indoor water needs; and septic system for the on-site disposal of household wastewater and sewage. In this manner, an integrated analysis procedure was developed for the analysis and design of off-grid, off-pipe homes, and was demonstrated for six U.S. climate locations. The results of the analysis indicated that achieving self-sufficiency for energy, water and sewage disposal was possible is all climates provided the systems for the collection and storage of renewable resources were large. On the other hand, the utilization of these systems was small for locations, where the year-to-year and seasonal variations in the weather conditions and availability of climate resources was large. For increased system utilization, minimization of the peak building needs, utilization of harvested energy for secondary purposes, and considering alternative systems for such applications are preferred.
Files in this item: 1MALHOTRA-DISSERTATION.pdf (9.308Mb)
Building Design and Operation for Improving Thermal Comfort in Naturally Ventilated Buildings in a Hot-Humid ClimateSreshthaputra, Atch (November 29, 2007)[more][less]
Abstract: The goal of this research was to develop new techniques for designing and operating unconditioned buildings in a hot-humid climate that could contribute to an improvement of thermal performance and comfort condition. The recommendations proposed in this research will also be useful for facility managers on how to maintain unconditioned buildings in this climate. This study investigated two unconditioned Thai Buddhist temples located in the urban area of Bangkok, Thailand. One is a 100-year-old, high-mass temple. The other is a 5-year-old, lower-mass temple. The indoor measurements revealed that the thermal condition inside both temples exceed the ASHRAE-recommended comfort zone. Surprisingly, the older temple maintained a more comfortable indoor condition due to its thermal inertia, shading, and earth contacts. A baseline thermal and airflow model of the old temple was established using a calibrated computer simulation method. To accomplish this, HEATX, a 3-D Computational Fluid Dynamics (CFD) code, was coupled with the DOE-2 thermal simulation program. HEATX was used to calculate the airflow rate and the surface convection coefficients for DOE-2, and DOE-2 was used to provide physical input variables to form the boundary conditions for HEATX. In this way calibrated DOE-2/CFD simulation model was accomplished, and the baseline model was obtained. To investigate an improved design, four design options were studied: 1) a reflective or low-solar absorption roof, 2) R-30 ceiling insulation, 3) shading devices, and 4) attic ventilation. Each was operated using three modes of ventilation. The low-absorption roof and the R-30 ceiling insulation options were found to be the most effective options, whereas the shading devices and attic ventilation were less effective options, regardless of which ventilation mode was applied. All design options performed much better when nighttime-only ventilation was used. Based on this analysis, two prototype temples was proposed (i.e., low-mass and high-mass temples). From the simulation results of the two prototypes, design and operation guidelines are proposed, which consist of: 1) increased wall and ceiling insulation, 2) white-colored, low-absorption roof, 3) slab-on-ground floor, 4) shading devices, 5) nighttime-only ventilation, 6) attic ventilation, and 7) wider openings to increase the natural ventilation air flow windows, wing walls, and vertical fins.
Files in this item: 1ESL-TH-03-05-01.pdf (18.16Mb)
Development and Application of a Procedure to Estimate Overall Building and Ventilation Parameters from Monitored Commercial Building Energy UseDeng, Song (May 1997)[more][less]
Abstract: This thesis proposes and validates a simplified model appropriate for parameter identification and evaluates several different inverse parameter identification schemes suitable for use when heating and cooling data from a commercial building are available. The validation has been performed using such data generated from a detailed building simulation program for different building geometries and building mass levels in two different climatic locations. Such a synthetic evaluation will validate the model used as well as determine the best parameter identification scheme, i.e., one likely to yield the most accurate set of parameter estimates. A multistep identification scheme has been found to yield very accurate results, and a more careful evaluation has been performed in order to evaluate its accuracy and stability with synthetic data against the effects of solar energy, HVAC system operation, internal load schedule, building thermal mass and geometry, and climatic location. This method is also evaluated using data from different time periods and when utility bill data (i.e. monthly data) only is available. The model is then applied to energy use data from two buildings being monitored under the Texas LoanSTAR Program, which are in different locations and have different HVAC systems. With parameters thus determined, two energy use indices, Energy Delivery Efficiency (EDE) and Multizone Efficiency Index (MEI), are calculated to present some insights into the benefits of retrofit from a constant volume (CV) to a variable air volume (VAV) system and of continuous commissioning (CC) work done to these two buildings, respectively. Uses and limitations of EDE and MEI are also discussed. Based on these findings, it is suggested that the multistep regression approach is an accurate and practical building physical parameter determination method, and the combined use of the EDE and MEI indices calculated from these parameters can provide insights into the HVAC system, and the potential for optimizing its operation.
Files in this item: 1ESL-TH-97-05-02.pdf (23.32Mb)
Development of a Transient Heat and Mass Transfer Model of Residential Attics to Predict Energy Savings Produced by the Use of Radiant BarriersMedina, M. A. (Energy Systems Laboratory (http://esl.tamu.edu), December 1992)[more][less]
Abstract: A transient heat and mass transfer model was developed to predict ceiling heat gain/loss through the attic space in residences and to accurately estimate savings in cooling and heating loads produced by the use of radiant barriers. The model accounted for transient conduction, convection and radiation and incorporated moisture and air transport across the attic. Environmental variables such as solar loads on outer attic surfaces and sky temperatures were also estimated. The model was driven by hourly weather data which included: time, outdoor air temperature, horizontal sun and sky radiation, wind speed and direction, relative humidity (dew point), and cloud cover data. The outputs of the model were ceiling heat fluxes, inner and outer heat fluxes from all surfaces, inner and outer surface temperatures and attic air temperatures. Transient conduction was modeled using response factors. Response factors were calculated for each attic component based on construction type. Convective heat transfer was modeled using “flat plate” correlations found in the literature and radiative heat transfer was modeled using radiation enclosure theory. Moisture was incorporated via a condensation/evaporation model. A new procedure was developed to account for attic air stratification. Both forced and natural attic ventilation patterns were added to the model for three types of louver combination arrangements. An iterative technique was used to solve a set of simultaneous heat balance equations. The model predictions were compared to experimental data gathered throughout a three year experimental effort of side-by-side testing of attics retrofit with radiant barriers. The model was compared to the experimental data for a variety of situations which included: different attic insulation levels, various attic airflow rates, cooling and heating seasons, and different radiant barrier orientations. The model predicted ceiling heat flows within 10% for most cases. The model was used to run simulations and parametric studies under a diversity of climates, insulation levels and attic airflow patterns. Model predictions and results were presented on the basis of savings produced by the use of radiant barriers. Hourly, daily, and seasonal predictions by the model were in excellent agreement with observed experimental data and with literature.
Files in this item: 1ESL-TH-92-12-04.pdf (5.868Mb)
Development of an automated methodology for calibration of simplified air-side HVAC system models and estimation of potential savings from retrofit/commissioning measuresBaltazar Cervantes, Juan Carlos (Texas A&M University, December 2006)[more][less]
Abstract: This dissertation provides one methodology to determine potential energy savings of buildings with limited information. This methodology is based upon the simplified energy analysis procedure of HVAC systems and the control of the comfort conditions. Numerically, the algorithm is a tailored exhaustive search over all the independent variables that are commonly controlled for a specific type of HVAC system. The potential energy savings methodology has been applied in several buildings that have been retrofitted and/or commissioned previously. Results from the determined savings for the Zachry building at Texas A&M after being commissioned show a close agreement to the calculated potential energy savings (about 85%). Differences are mainly attributed to the use of simplified models. Due to the restriction of limited information about the building characteristics and operational control, the potential energy savings method requires the determination of parameters that characterize its thermal performance. Thus, a calibrated building is needed. A general procedure has been developed to carry out automated calibration of building energy use simulations. The methodology has been tested successfully on building simulations based on the simplified energy analysis procedure. The automated calibration is the minimization of the RMSE of the energy use over daily conditions. The minimization procedure is fulfilled with a non-canonical optimization algorithm, the Simulated Annealing, which mimics the Statistical Thermodynamic performance of the annealing process. That is to say, starting at a specified temperature the algorithm searches variable-space states that are steadier, while heuristically, by the Boltzmann distribution, the local minima is avoided. The process is repeated at a new lower temperature that is determined by a specific schedule until the global minimum is found. This methodology was applied to the most common air-handler units producing excellent results for ideal cases or for samples modified with a 1% white noise.
Files in this item: 1etd-tamu-2006C-MEEN-BALTAZA.pdf (3.649Mb)
Sung, Yong Hoon (Texas A&M University, August 2004)[more][less]
Abstract: In this dissertation I will present and test a model linking actual applicant-interviewer demographic, human capital, and cultural capital similarity to an interviewer's recommendation to hire. Actual similarity is proposed to influence an interviewer's perceptions of similarity with an applicant. These perceptions, in turn, lead to the interviewer's perceptions of the applicant's Person-Organization (PO) fit and the applicant's Person-Job (PJ) fit. Two main mechanisms are proposed to mediate the relationship between an interviewer's perceptions of similarity and an interviewer's perceptions of an applicant's fit: liking and negative behavioral expectations. Lastly, both an interviewer's PO and PJ fit perceptions of an applicant are posited to influence the interviewer's recommendation to hire. A total of 118 interviewer-applicant dyads contacted through the Career Center Office at a University located in the southwestern United States participated in the study. Results partially support the model. An interviewer's perceptions of similarity with an applicant are positively related to an interviewer's fit evaluations. An interviewer's negative behavioral expectations of an applicant mediate this relationship. Furthermore, perceived similarity is positively related to an interviewer's liking of an applicant. In turn, liking is positively related to an interviewer's PO fit perceptions. However, liking does not function as a mediator between perceived similarity and fit evaluations. Finally, fit evaluations are positively related to hiring recommendations. I discuss the main implications of the study as well as strengths, limitations, and future research.
Files in this item: 1etd-tamu-2004B-ARCH-Sung-2.pdf (8.657Mb)
Song, Suwon (August 2006)[more][less]
Abstract: The concept of Measurement and Verification (M&V) of a new building continues to become more important because efficient design alone is often not sufficient to deliver an efficient building. Simulation models that are calibrated to measured data can be used to evaluate the energy performance of new buildings if they are compared to energy baselines such as similar buildings, energy codes, and design standards. Unfortunately, there is a lack of detailed M&V methods and analysis methods to measure energy savings from new buildings that would have hypothetical energy baselines. Therefore, this study developed and demonstrated several new methodologies for evaluating the energy performance of new commercial buildings using a case-study building in Austin, Texas. First, three new M&V methods were developed to enhance the previous generic M&V framework for new buildings, including: 1) The development of a method to synthesize weathernormalized cooling energy use from a correlation of Motor Control Center (MCC) electricity use when chilled water use is unavailable, 2) The development of an improved method to analyze measured solar transmittance against incidence angle for sample glazing using different solar sensor types, including Eppley PSP and Li-Cor sensors, and 3) The development of an improved method to analyze chiller efficiency and operation at part-load conditions. Second, three new calibration methods were developed and analyzed, including: 1) A new percentile analysis added to the previous signature method for use with a DOE-2 calibration, 2) A new analysis to account for undocumented exhaust air in DOE-2 calibration, and 3) An analysis of the impact of synthesized direct normal solar radiation using the Erbs correlation on DOE-2 simulation. Third, an analysis of the actual energy savings compared to three different energy baselines was performed, including: 1) Energy Use Index (EUI) comparisons with sub-metered data, 2) New comparisons against Standards 90.1-1989 and 90.1-2001, and 3) A new evaluation of the performance of selected Energy Conservation Design Measures (ECDMs). Finally, potential energy savings were also simulated from selected improvements, including: minimum supply air flow, undocumented exhaust air, and daylighting.
Files in this item: 1SONG-DISSERTATION.pdf (14.44Mb)
An evaluation of the bioclimatic chart for choosing design strategies for a thermostatically-controlled residence in selected climatesVisitsak, Sopa (December 2007)[more][less]
Abstract: To be successful in sustainable building design, architects must consider energy efficient design strategies in the early design stage. Unfortunately, many architects still rely on simplified analysis, synthesis techniques, and historical examples. Although, building energy simulations are becoming more common in the design of buildings, architects rarely use simulation in the early design stage. The “Bioclimatic” charts have been used in the early design stage to define potential building design strategies to achieve indoor thermal comfort. Currently, many architects use the Givoni-Milne bioclimatic design chart (Milne and Givoni, 1979), which was developed based on principle reasoning and heuristics. There have been many attempts to develop computerized programs to further the bioclimatic analysis; however, there have been very limited efforts to test and evaluate the design strategies of the chart using simulations of a thermostatically-controlled building. Therefore, the purpose of this research is to promote comfortable buildings that reduce energy use through appropriate building design strategies. The objectives of the research are to develop a more accurate bioclimatic chart for a thermostaticallycontrolled residence by testing and evaluating the Givoni-Milne bioclimatic chart. The analysis is performed with DOE-2.1e program (Winkelmann, 1993) and TMY2 weather data (Marion and Urban, 1995) for several climates. To achieve these objectives, four main tasks were accomplished: 1) investigate the Givoni-Milne Bioclimatic Chart using representative weather data from several climates, 2) analyze and modify the design strategy boundaries using DOE-2 program and TMY2 weather data to simulate the effects of varied conditions of a thermostatically-controlled residence in different climates, 3) compare these new design strategy boundaries to the original Givoni-Milne design strategy boundaries, and 4) develop general guidelines for the new bioclimatic chart. In summary, there were some differences in the results from the Givoni-Milne bioclimatic chart and the DOE-2 simulation results. These results imply that without further modification, the G-M Chart may have only a limited use for a thermostaticallycontrolled residence. Therefore, to improve the usefulness of the bioclimatic chart the new bio-climatic chart for choosing design strategies for a thermostatically-controlled residence in the hot-humid climate of Houston, Texas, was developed. This new bioclimatic chart for a thermostatically-controlled residence will be a useful tool for architects and engineers in the early design stage. Similar versions of the new bioclimatic for other climates could then be developed.
Files in this item: 1VISITSAK-DISSERTATION.pdf (35.16Mb)
An Experimental Investigaton of the Effect of Oil on Convective Heat Trasfer and Pressure Drop of a HFC-32/HRC-125 MixtureMcJimsey, Bert Ashford (December 1994)[more][less]
Abstract: The heat transfer coefficients and pressure drops of HCFC-22 and a 50% mass mixture of HFC-32/HFC-125 were experimentally measured under flow boiling conditions in a smooth tube. The refrigerants were flowed through an 8 mm diameter smooth tube at mass fluxes of 277, 434, 520 and 700 kg/sm^2. Heat fluxes were applied at values of 5100, 7100 and 11000 W/m^2. The heat transfer coefficients and pressure drops were measured at refrigerant qualities of 10, 15, 20, 25, 30, 40 and 60 percent. The refrigerants were examined at temperatures near 4°C. Oil was added to the HFC-32/HFC-125 mixture in concentrations of 2.6% and 5.4%. Experiments were repeated with the oil laden refrigerant. The heat transfer coefficients for HCFC-22 increased with quality, mass flux and heat flux. The heat transfer coefficients for HFC-32/HFC-125 often decreased at low qualities and increased with quality at high qualities. The pressure drop increased with quality and mass flux for both refrigerants. The heat transfer had a minimal effect upon pressure drop. HFC-32/HFC-125 had a lower pressure drop than HCFC-22 for all conditions. The addition of oil increased the pressure drop. A pressure drop correlation and heat transfer correlation were developed for HFC-32/HFC-125.
Files in this item: 1ESL-TH-94-12-12.pdf (4.536Mb)
An Improved Procedure for Developing a Calibrated Hourly Simulation Model of an Electrically Heated and Cooled Commercial BuildlingBou-Saada, Tarek Edmond (Energy Systems Laboratory, December 1994)[more][less]
Abstract: With the increased use of building energy simulation programs, calibration of simulated data to measured data has been recognized as an important factor in substantiating how well the model fits a real building. Model calibration to measured monthly utility data has been utilized for many years. Recently, efforts have reported calibrated models at the hourly level. Most of the previous methods have relied on very simple comparisons including bar charts, monthly percent difference time-series graphs, and x-y scatter plots. A few advanced methods have been proposed as well which include carpet plots and comparative 3-D time-series plots. Unfortunately, at hourly levels of calibration, many of the traditional graphical calibration techniques become overwhelmed with data and suffer from data overlap. In order to improve upon previously established techniques, this thesis presents new calibration methods including temperature binned box-whisker-mean analysis to improve x-y scatter plots, 24-hour weather-daytype box-whisker-mean graphs to show hourly temperature-dependent energy use profiles, and 52-week box-whisker-mean plots to display long-term trends. In addition to the graphical calibration techniques, other methods are also used including indoor temperature calibration to improve thermostat schedules and architectural rendering as a means of verifying the building envelope dimensions and shading placement. Several statistical methods are also reviewed for their appropriateness including percent difference, mean bias error (MBE), and the coefficient of variation of the root mean squared error. Results are presented using a case study building located in Washington, D.C. In the case study building, nine months of hourly whole-building electricity data and site-specific weather data were measured and used with the D0E-2.1D building simulation program to test the new techniques. Use of the new calibration procedures were able to produce a MBE of -0.7% and a CV(RMSE) of 23.1% which compare favorably with the most accurate hourly neural network models.
Files in this item: 1ESL-TH-94-12-01.pdf (63.93Mb)
Noboa, Homero L. (August 1993)[more][less]
Abstract: The purpose of this project was to model and quantify the increase of the absorptivity of radiant barriers caused by the accumulation of dust on the surface of radiant barriers. This research was the continuation of a previous work by the author at Texas A&M University in which a radiation energy balance inside the attic enclosure was developed. The particles were considered as flat, circular planes, all having the same radii. That early model showed that there was a linear relationship between the fraction of area of the foil covered by dust and the mean absorptivity of the dusty radiant barrier. In the present work, it was found that the assumption of treating the dust particles as plane circles, underestimated the effective area of the particles by about 20%. Experimental measurements indicated that dust particles achieved the same temperature as the radiant barrier. The new model used the linear relationship just described, and simulated the dust particles as flat circular planes having random radii and laying in random locations within the radiant barrier surface. The new model calculated the fraction of radiant barrier area covered by particles using a digital array in which the clean barrier was represented as zeroes and the dust particles were represented as a set of ones appropriately dimensioned inside the array. The experimentation used natural dust and Arizona Road Test Dust. Using an infrared emissometer, the emissivities (absorptivities) of the clean and dusty barriers were measured and using an electronic scale, the dust loading was measured. An electron microscope was used to experimentally find the fraction of radiant barrier covered by the dust particles to correlate the experimentally found absorptivity with the experimentally found fraction of dust coverage. The limited experimental data available were also used to correlate the absorptivity of the dusty radiant barrier with the time of dust accumulation and the location of the barrier inside the attic. A linear relationship between the absorptivity and the time of dust accumulation was found that can be applied to predict future barrier effectiveness based upon the rate of dust accumulation for a given location.
Files in this item: 1ESL-TH-93-08-02.pdf (4.280Mb)
An investigation of methods for reducing the use of non-renewable energy resources for housing in ThailandRasisuttha, Sakkara (Texas A&M University, May 2003)[more][less]
Abstract: The purpose of this research is to develop methods that reduce energy consumption in a residential building in a hot and humid climate region (Thailand) using efficient architectural building components and renewable energy (solar energy) to produce electricity, domestic hot water, and supplemental cooling by night sky radiation. Improving the architectural building components, including building materials, is an option to reduce energy consumption in a building. Using renewable energy sources is another option to reduce the consumption of non-renewable energy. In residential buildings, solar energy has been utilized for space heating and domestic hot water using active solar collector systems and for generating electricity using photovoltaic (PV) systems. One photovoltaic system, the hybrid photovoltaic-thermal (PV-T) collector system, has been developed by several researchers over the last 20 years. The hybrid photovoltaic-thermal (PV-T) collector system is a combination photovoltaic (for producing electricity) and solar thermal collector (for producing hot water). Theoretical and experimental studies of this collector have highlighted the advantages of the hybrid PV-T collector system over separate systems of PV and solar collector in term of system efficiency and economics. Unfortunately, very little experimental data exists that demonstrates the advantages of a combined system. Therefore, one of the objectives of this study conducted was an experimental study of this system as an auxiliary energy source for a residential building. Night sky radiation has also been studied as a cooling strategy. However, no attempt so far could be found to integrate it to a hybrid PV-T collector system. The night sky radiation strategy could be operated with the hybrid PV/T collector system by using existing resources that are already present in the solar system. The integration of the night sky radiation into the hybrid PV-T collector system should yield more productivity of the system than the operation of the Hybrid PVT system alone. The research methods used in this work included instrumentation of a case-study house in Thailand, an experimental PV-T collector system, and a calibrated building thermal simulation. A typical contemporary Thai residential building was selected as a case-study house. Its energy use and local weather data were measured and analyzed. Published energy use of Thai residential buildings was also analyzed as well to determine average energy consumption. A calibrated computer model of the case-study building was constructed using the DOE-2 program. A field experiment of the thermal PV system was constructed to test its ability to simultaneously produce electricity and hot water in the daytime, and shed heat at night as a cooling strategy (i.e., night sky radiation). The resultant electricity and hot water produced by the hybrid PV-T collector system helped to reduce the use of non-renewable energy. The cooling produced by the night sky radiation also has to potential to reduce the cooling load. The evaluation of the case-study house and results of the field experiment helped to quantify the potential reduction of energy use in Thai residential buildings. This research provided the following benefits: 1) experimental results of a hybrid PV-T solar collector system that demonstrates its performance compared to typical system of separate photovoltaic and solar collector, 2) results of night sky radiation experiments using a photovoltaic panel as a radiator to demonstrate the performance of this new space cooling strategy, and 3) useful data from the case-study house simulation results and guidelines to assist others in transferring the results to other projects.
Files in this item: 1etd-tamu-2005A-ARCH-Rasisut.pdf (7.261Mb)
Im, Piljae (December 2009)[more][less]
Abstract: A methodology to develop an easy-to-use toolkit for the preliminary design of high performance schools in hot and humid climates was presented. The toolkit proposed in this research will allow decision makers without simulation knowledge easily to evaluate accurately energy efficient measures for K-5 schools, which would contribute to the accelerated dissemination of energy efficient design. For the development of the toolkit, first, a survey was performed to identify high performance measures available today being implemented in new K-5 school buildings. Then an existing case-study school building in a hot and humid climate was selected and analyzed to understand the energy use pattern in a school building and to be used in developing a calibrated simulation. Based on the information from the previous step, an as-built and calibrated simulation was then developed. To accomplish this, five calibration steps were performed to match the simulation results with the measured energy use. The five steps include: 1) Using an actual 2006 weather file with measured solar radiation, 2) Modifying lighting & equipment schedule using ASHRAE's RP-1093 methods, 3) Using actual equipment performance curves (i.e., scroll chiller), 4) Using the Winkelmann's method for the underground floor heat transfer, and 5) Modifying the HVAC and room setpoint temperature based on the measured field data. Next, the calibrated simulation of the case-study K-5 school was compared to an ASHRAE Standard 90.1-1999 code-compliant school. In the next step, the energy savings potentials from the application of several high performance measures to an equivalent ASHRAE Standard 90.1-1999 codecompliant school. The high performance measures applied included the recommendations from the ASHRAE Advanced Energy Design Guides (AEDG) for K- 12 and other high performance measures from the literature review as well as a daylighting strategy and solar PV and thermal systems. The results show that the net energy consumption of the final high performance school with the solar thermal and a solar PV system would be 1,162.1 MMBtu, which corresponds to the 14.9 kBtu/sqft-yr of EUI. The calculated final energy and cost savings over the code compliant school are 68.2% and 69.9%, respectively. As a final step of the research, specifications for a simplified easy-to-use toolkit were then developed, and a prototype screenshot of the toolkit was developed. The toolkit is expected to be used by non-technical decision-maker to select and evaluate high performance measures for a new school building in terms of energy and cost savings in a quick and easy way.
Files in this item: 1IM-DISSERTATION.pdf (44.43Mb)
A Methodology to Develop Monthly Energy Use Models From Utility Billing Data For Seasonally Scheduled Buildings: Application to SchoolsWang, W. (Energy Systems Laboratory (http://esl.tamu.edu), December 1998)[more][less]
Abstract: The measured energy savings from retrofits in buildings in the Texas LoanSTAR program are determined as the difference between the energy consumption predicted by a baseline model and the measured energy consumption during the post-retrofit period. Savings measurement for buildings such as primary and secondary schools is very difficult due to the special operating schedules of these buildings. Currently, savings are often determined by simple pre-post utility bill comparison; they may also be determined with two separate models for the baseline: a 3-P model for non-summer months, and a mean model for the summer months. (Landman 1996). This thesis proposes a methodology for developing baseline models of energy use for buildings such as schools which have important daily and seasonal variations in occupancy. The method utilizes utility billing data, but also explicitly incorporates occupancy rate, permitting a generalized model which retains the distinction between energy use levels during occupied and unoccupied days of the year. The proposed methodology has been evaluated against the one proposed by Landman for 10 schools in Texas.
Files in this item: 1ESL-TH-98-12-01.pdf (25.40Mb)
A methodology to evaluate energy savings and NOx emissions reductions from the adoption of the 2000 International Energy Conservation Code (IECC) to new residences in non-attainment and affected counties in TexasIm, Piljae (Texas A&M University, December 2003)[more][less]
Abstract: Currently, four areas of Texas have been designated by the United States Environmental Protection Agency (EPA) as non-attainment areas because they exceeded the national one-hour ground-level ozone standard of 0.12 parts-per-million (ppm). Ozone is formed in the atmosphere by the reaction of Volatile Organic Compounds (VOCs) and Nitrogen Oxides (NOx) in the presence of heat and sunlight. In May 2002, The Texas State Legislature passed Senate Bill 5, the Texas Emissions Reduction Plan (TERP), to reduce the emissions of NOx by several sources. As part of the 2001 building energy performance standards program which is one of the programs in the TERP, the Texas Legislature established the 2000 International Energy Conservation Code (IECC) as the state energy code. Since September 1, 2001, the 2000 IECC has been required for newly constructed single and multifamily houses in Texas. Therefore, this study develops and applies portions of a methodology to calculate the energy savings and NOx emissions reductions from the adoption of the 2000 IECC to new single family houses in non-attainment and affected counties in Texas. To accomplish the objectives of the research, six major tasks were developed: 1) baseline data collection, 2) development of the 2000 IECC standard building simulation, 3) projection of the number of building permits in 2002, 4) comparison of energy simulations, 5) validation and, 6) NOx emissions reduction calculations. To begin, the 1999 standard residential building characteristics which are the baseline construction data were collected, and the 2000 IECC standard building characteristics were reviewed. Next, the annual and peak-day energy savings were calculated using the DOE-2 building energy simulation program. The building characteristics and the energy savings were then crosschecked using the data from previous studies, a site visit survey, and utility billing analysis. In this thesis, several case study houses are used to demonstrate the validation procedure. Finally, the calculated electricity savings (MWh/yr) were then converted into the NOx emissions reductions (tons/yr) using the EPA's eGRID database. The results of the peak-day electricity savings and NOx emissions reductions using this procedure are approximately twice the average day electricity savings and NOx emissions reductions.
Files in this item: 1etd-tamu-2003C-ARCH-Im-1.pdf (11.38Mb)