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 potenti...
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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.
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...
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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 softwar...
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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.
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 cha...
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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.
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 c...
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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 hinde...
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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.
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 pub...
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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.
This paper presents an integrated damper and pressure reset (IDPR) method for variable air volume (VAV) system fan control. The IDPR method controls the static pressure at a minimum required level while maintaining at...
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This research aims to explore how Human Computation can be used to aid economic development in communities experiencing extreme poverty throughout the world. Work is ongoing with a community in rural Kenya to connect ...
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Diffuse reflections have received increasing attention in architectural acoustics over the past quarter century. The term diffuse refers to non-specular directions. This paper identifies three mechanisms that cause di...
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ISBN:
(纸本)0784407983
Diffuse reflections have received increasing attention in architectural acoustics over the past quarter century. The term diffuse refers to non-specular directions. This paper identifies three mechanisms that cause diffuse reflections. Practitioners have found that changing specular reflections into diffuse reflections can reduce noise and echoes both indoors and outdoors. Developers of acoustical modeling software have also found that modeling diffuse in additional to specular reflections produces more accurate predictions. The final portion of this paper presents results for a study of scattering coefficients in acoustical modeling software. Copyright ASCE 2006.
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