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114th Annual ASEE Conference and Exposition, 2007

作者： Bielefeldt, Angela Amadei, Bernard Sandekian, Robyn University of Colorado Boulder United States Department of Civil Environmental and Architectural Engineering University of Colorado Boulder United States Program Department of Civil Engineering University of Colorado Boulder United States Engineering for Developing Communities Program College of Engineering and Applied Science University of Colorado Boulder United States

A new course, engineering for the Developing World (EDW), has been taught since fall 2005. The course goals include: (i) introduce students to open ended problems at the community level;(ii) help students develop the skills to solve those problems and provide holistic engineering solutions that are sustainable and appropriate to the community being served;(iii) help students develop cultural and social awareness;(iv) help students work in interdisciplinary teams;(v) give students the opportunity to reflect on the importance of their community service;(vi) give students a professional work ethic, and (vii) help students gain a better understanding of the importance of engineering in society and in community development. Two different models for the course have been used: in year one, a single team of three students worked on two different projects for a community in Rwanda over two semesters, earning six credits that could be applied as technical electives in their respective majors. In year two, twelve students in three teams worked on a wastewater treatment/reuse design for a community in Sonora, Mexico. In this format, students earned 3 to 4 credits for the course, which counted as the capstone design experience in their curricula. The students self-selected this international project from among three project options (the other two were service learning projects within the state) in the capstone Environmental engineering design class. Student evaluations of the EDW course are presented and contrasted against feedback from students who worked on other service learning projects or a traditional civil engineering project. © American Society for engineering Education, 2007.

关键词： engineering education

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Room acoustics in coupled volume spaces

Room acoustics in coupled volume spaces

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AEI 2006

作者： Bradley, David T. Wang, Lily M. Architectural Engineering Program University of Nebraska - Lincoln Peter Kiewit Institute 1110 S. 67th Street Omaha NE 68182-068

ISBN: (纸本)0784407983

The study of sound in the built environment is finding more awareness in the 21st century. As this awareness has increased, and as computing power has grown, the method of computer modeling for studying room acoustics in such settings as classrooms, offices, and performances spaces has taken great strides in recent years. Of particular interest has been the study of the coupled volume space due to its unique ability to provide contrasting acoustical phenomenon. A coupled volume room is generally defined as a space consisting of a large main volume containing high levels of sound absorption connected through small sonically transparent apertures to a smaller coupled volume with lower absorption. When a sound source is placed in the main volume, this configuration may lead to sound energy being trapped in the coupled volume, which is then released back into the main space at a later time. The delay in sound energy from the coupled volume results in a double-sloped sound decay in the main volume, resulting in intriguing acoustical phenomenon not typically seen in single volume spaces. The real world application of this type of space is most commonly found in concert hall settings. The use of computer modeling to study this relatively complex type of space is a comparatively new development, and the limits of the method have yet to be fully explored. This research focuses on determining the effects of the architectural parameters, absorption level and aperture size, on the room acoustics in coupled volume spaces. A coupled volume concert hall computer model was constructed and analyzed in order to determine these effects. Comparative analysis of several configurations of the model reveals that increased absorption in the coupled volume decreases double slope effect, while the effect generally peaks for a relatively small aperture opening size. Copyright ASCE 2006.

关键词： Acoustics

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Impact of Building Design and Operating Strategies on Urban Heat Island Effects Part II: Sensitivity Analysis

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Journal of engineering for Sustainable Buildings and Cities 2024年第3期5卷 031005页

作者： Ameer, Baqer Krarti, Moncef Department of Civil Environmental and Architectural Engineering Building Systems Program University of Colorado Boulder Boulder 80309 CO United States Kuwait Institute for Scientific Research Safat 13109 Kuwait

This study investigates the mutual thermal interactions between buildings and the microclimate within urban area centers. Buildings are the primary energy consumers in cities, and one of the main causes of the urban heat island (UHI) formation. In this article, a flexible simulation environment is developed and used to model the mutual thermal interactions between building energy systems and their urban surroundings in Phoenix, AZ, characterized by its hot climate. The impacts of various operating strategies for both commercial and residential buildings are assessed on both UHI effects and energy consumption. Specifically, the study evaluates the impacts of indoor temperature settings, precooling strategies, and air infiltration/exfiltration rates. It has been found that heat rejected by air conditioning systems significantly impacts UHI formation in urban centers located in hot climates. Specifically, commercial buildings were found to cause more UHI effects than residential buildings due to higher cooling loads. The impacts of heat rejected from heating, ventilating, and air conditioning (HVAC) systems are found to be more dominant than that from air exfiltration on the microclimate of urban centers. For urban center made up of commercial buildings with a street aspect ratio of 2, heat from air exfiltration is estimated to be as low as 10% of the heat rejected by HVAC systems. Copyright © 2024 by ASME.

关键词： air conditioning air infiltration building energy efficiency cities precooling controls temperature settings thermal mass urban heat island

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Accuracy tests for simulations of VAV dual-duct, single-zone, four-pipe fan-coil, and four-pipe induction air-handling systems

Accuracy tests for simulations of VAV dual-duct, single-zone...

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2006 Annual Meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, ASHRAE

作者： Yuill, G.K. Haberl, J.S. Caldwell, J.S. ASHRAE Architectural Engineering Program University of Nebraska Lincoln Department of Architecture Texas A and M University College Station TX James Posey Associates Baltimore MD

This paper provides a method for verifying the accuracy of computer models that simulate the performance of the air-handling components of four types of heating, ventilating, and air-conditioning systems: the dual-fan VAV dual-duct system, the single-zone system, the four-pipe fan-coil system, and the four-pipe induction system. To accomplish this, a detailed description of each system and its operating parameters was developed and a set of eight test conditions was generated, consisting of carefully chosen space loads and weather conditions. Each of the systems was simulated at each of the defined conditions. The thermodynamic properties at each point in the system, as well as the heating and cooling coil loads, were calculated. The calculations were then repeated by a second analyst using an independently developed program. The maximum deviation in the total coil loads was 1.8%, and the average of the absolute deviations was 0.4%. These validated results can be used by program developers or users to test the performance of the air-side simulations contained in most building energy analysis computer programs. © 2006 ASHRAE.

关键词： Air conditioning

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Field testing to estimate ozone emission rates of in-duct air cleaners in occupied homes 13

Field testing to estimate ozone emission rates of in-duct ai...

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13th International Conference on Indoor Air Quality and Climate, Indoor Air 2014

作者： Shaughnessy, Richard Reisdorph, David Morrison, Glenn Indoor Air Program Department of Chemical Engineering University of Tulsa OK United States Civil Architectural and Environmental Engineering Department Missouri University of Science and Technology RollaMO United States

Considerable concern, research, and regulation have been linked to the use of portable air cleaners that intentionally (or unintentionally) produce ozone in the indoor environment. This research focuses on the potential for electrically connected in-duct air cleaners to increase indoor concentrations of ozone in field sites. The objective of the research was to measure the incremental increase in the ozone concentration and estimate the in-use ozone emission rate when a commercially available in-duct air cleaning device is operating. Devices tested included UV lamps, photocatalytic oxidation systems and electrostatic precipitators. A field method was implemented in 6 houses and 1 commercial space. In-duct air cleaners produced ozone to varying degrees, increasing the indoor home concentration by as much as 134 ppb while operating normally in residences. Emission rates as high as 436 mg h-1 were observed., Explicit ozone generators were the highest emitters, raising indoor concentrations above 50 ppb in most tests. Most other devices did not raise ozone concentrations above 50 ppb and ozone emission rates for these devices were below 50 mg h-1.

关键词： Ozone

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Acoustical prediction methods for heating, ventilating, and air-conditioning (HVAC) systems

Acoustical prediction methods for heating, ventilating, and ...

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19th National Conference on Noise Control engineering 2005, Noise-Con 2005

作者： Ryherd, Steven R. Wang, Lily M. Architectural Engineering Program University of Nebraska - Lincoln PKI 1110 S. 67th St. Omaha NE 68182 United States

ISBN: (纸本)9781622762712

The goal of this project was to compare and contrast various aspects of acoustical prediction methods for heating, ventilating, and air-conditioning (HVAC) systems. The three methods included two commonly used software programs and a custom spreadsheet developed by the authors based on the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE) Applications Handbook. Preliminary results indicate relatively good agreement between the three methods analyzed. The degree of disparity is predominantly affected by the assumptions required by the end user. Research methods and results will be presented. This project provides a greater understanding of these acoustical prediction methods and their limitations.

关键词： Handbooks

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Appropriate characterization of background noise levels in the workplace

Appropriate characterization of background noise levels in t...

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AEI 2006

作者： Bowden, Erica E. Wang, Lily M. Architectural Engineering Program University of Nebraska - Lincoln PKI 1110 S. 67th St. Omaha NE 68182 United States

ISBN: (纸本)0784407983

Overall loudness is not the only quality of indoor background noise that affects occupants. The distribution of noise across frequency (pitch), whether or not the noise contains tones, and whether or not the noise changes over time must also be considered. There are several indoor noise criteria systems available to quantify the background noise in rooms, but many of them do not account for these factors. These systems are commonly used by architects and engineers, and often incorporated into manufacturer's data, design guides, and standards. There is much debate over which of the criteria systems best reflect how occupants will respond to noise. To examine these issues, an extensive study is being completed at the University of Nebraska investigating the effects of various types of air-conditioning noise on occupant productivity and perception. Results from performance tests and questionnaires are used to evaluate a number of these noise criteria systems. Specific implications of this project on characterizing noise in the workplace will be discussed. Copyright ASCE 2006.

关键词： Acoustic noise

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Evaluating energy savings potential in United States residential buildings

Evaluating energy savings potential in United States residen...

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Construction Research Congress 2012: Construction Challenges in a Flat World

作者： Kolahdoozan, Sami Leite, Fernanda Construction Engineering and Project Management Program Department of Civil Architectural and Environmental Engineering University of Texas at Austin 1 University Station C1752 Austin TX 78712 United States

ISBN: (纸本)9780784412329

There are currently many discussions on sustainability emphasizing the needs of infrastructure, lower energy consumption, durability, and recyclability. In the United States, residential buildings consume 22% of the country's total energy and also are responsible for 22% of carbon dioxide emitted to the environment. The main objective of this research is determining the potential energy savings in residential buildings in the U.S. To find energy savings potential, the Residential Energy Consumption Survey (RECS) was used. This dataset provides general information on condition of appliances and buildings components as well as energy consumption in residential buildings. Based on RECS, this study took a broad look at energy savings potential for space heating, air conditioning, refrigerators, freezers, and lighting in residential buildings. Results of this study indicate that 29% and 19% of energy used for space heating, space cooling can respectively be saved by improving building components such as glasses and thermal insulation. In addition, results of this study show that 5% of total electricity used in residential buildings is delivered to nonefficient refrigerators, freezers, and light bulbs. By realizing the aforementioned energy savings in buildings, not only will consumers pay less money for their energy bills, but also greenhouse gas emissions from buildings can be reduced. Also, results of this study can help decision makers allocate tax credits for different products in such a way as to encourage actions targeting higher energy savings. © 2012 ASCE.

关键词： Energy conservation

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Effects of noise on productivity: Does performance decrease over time?

Effects of noise on productivity: Does performance decrease ...

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AEI 2006

作者： Errett, Jessica Bowden, Erica E. Choiniere, Marc Wang, Lily M. Architectural Engineering Program University of Nebraska - Lincoln PKI 1110 S. 67th St. Omaha NE 68182 United States

ISBN: (纸本)0784407983

Most people at one time or another have found themselves irritated or distracted by the background noise in a building. The irritation might have resulted in minor aggravation or may have been dramatic enough to hinder their work. This leads us to ask whether occupants are increasingly aggravated by noise the longer they are exposed to it, or if they naturally habituate to their acoustic environment. In an effort to answer this question, a study was completed in the "Indoor Environment Lab" at the University of Nebraska. This lab resembles a typical office and was specially constructed to be acoustically and thermally controlled. Subjects completed 38 total hours of testing in the lab over multiple days, during which time they were exposed to several background noise conditions over 20, 40, 80, and 240 minute trials. During the trials, subjects completed a variety of performance tasks and answered questions about their perception of the noise, the thermal environment and various other factors. End results aid in understanding the prolonged effects of typical heating, ventilating, and air-conditioning (HVAC) noise on worker productivity and annoyance. Copyright ASCE 2006.

关键词： Acoustic variables control

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Acoustics of elementary school classrooms: Correlations of varying background noise level and reverberation time to student achievement.

Acoustics of elementary school classrooms: Correlations of v...

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38th International Congress and Exposition on Noise Control engineering 2009, INTER-NOISE 2009

作者： Ronsse, Lauren M. Wang, Lily M. Architectural Engineering Program University of Nebraska - Lincoln 1110 S. 67th St. Omaha NE 68182-0681 United States

ISBN: (纸本)9781615676903

This research correlates two classroom acoustic parameters, background noise level and reverberation time, with standardized student achievement scores in elementary school classrooms in a midwestern United States public school system. Previous research in this area has shown high background noise level and reverberation time in spaces negatively impacts children's learning and performance. However, the specific levels at which detrimental effects begin to occur have not been clearly defined. The recommendation in the ANSI S12.60 Classroom Acoustics Standard for unoccupied background noise level is 35 dBA. Because many of the previous classroom acoustics studies have targeted spaces with higher background noise levels, more research is needed to determine if the unoccupied background noise level must necessarily be this low. This study surveys a wide range of elementary school classrooms to determine what (if any) unoccupied background noise level and reverberation time are necessary for optimizing student achievement.

关键词： Reverberation

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