Architectural Engineering Commons^™

Investigations Of The Relationships Between Unoccupied Classroom Acoustical Conditions And Elementary Student Achievement, Lauren M. Ronsse

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Current building standards recommend specific unoccupied background noise levels and reverberation times for classroom spaces. While clear communication in elementary school classrooms may be critical for successful learning environments, the existing research does not show a consistent connection between the classroom acoustics parameters specified in building standards and student achievement. This research seeks to determine what acoustical conditions should be attained in elementary school classrooms to optimize student achievement.

In this dissertation, acoustical studies in two midwestern United States public school systems are described. Unoccupied background noise level (BNL) and reverberation time (RT) measurements were gathered in a range of …

Real-Time Power Monitoring, Home Automation And Sustainability, Wisam Nader

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

As the supply and demand of electrical energy is challenged within the context of environmental awareness and national security, the need to evaluate and advance each side is growing in importance. The electrical distribution system plays a critical role in the built environment as it is an enabling product, an intangible necessity used to power our systems. In order to manage our energy and prevent the consequences caused by energy wastage we need to develop tools for the built environment to become elastic with its consumption to respond to the national smart grid. To advance the research in this field, …

Adaptive Photovoltaic Configurations For Decreasing The Electrical Mismatching Losses, Mohamed Amer Chaaban

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Electrical mismatching losses in photovoltaic systems are of great interest to system designers. In this thesis, an adaptive photovoltaic (PV) system is proposed based on novel flexible switch matrixes that form different possible topologies. This system maximizes the generated power in real-time for utility interactive systems in a modified inverter configuration. The proposed system uses fewer components and achieves maximum efficiency during shading and module mismatches by reconfiguring the PV modules based on real-time solar insolation, current operational conditions, and maximum efficiency criterion. Simulation tools are used to demonstrate that the proposed topologies provide improvement in efficiency over existing traditional …

Impacts Of Static Pressure Reset On Vav System Air Leakage, Fan Power And Thermal Energy- Part 1: Theoretical Model And Simulation, Mingsheng Liu, Jingjuan Feng, Zhan Wang, Lixia Wu, Keke Zheng, Xiufeng Pang

Durham School of Architectural Engineering and Construction: Faculty Publications

As for a variable air volume (VAV) System, the air duct static pressure is a typical control variable maintained by modulating supply fan speed. The static pressure equals to the summation of the duct pressure loss downstream of the sensor to the terminal box and box inlet static pressure. Typically, the air duct static pressure is set as a constant set point based on the system design information and sensor location. However, under partial load conditions, the terminal dampers have to be closed more since the required airflow which directly leads to much less pressure loss. This the static pressure …

Application Of Wireless Sensor Network (Wsn) Technologies In Optimal Static Pressure Reset In Variable Air Volume (Vav) System, Keke Zheng, Haorong Li, Huojun Yang

Durham School of Architectural Engineering and Construction: Faculty Publications

Optimization of the static pressure reset is always critical in the pursuit of maximum savings of fan power and thermal energy consumption in a VAV system. This paper theoretically investigated three static pressure reset methods, i.e. VAV terminal unit damper position based, outside air temperature based and air flow based, and proposed an optimal static pressure reset method. Subsequently, hourly simulations of a building in Omaha, Nebraska, USA, was implemented and validated that the VAV system with the optimal reset method could consume the least fan energy without sacrificing thermal comfort. Furthermore, in consideration of typical advantages or wireless technologies …

Economizer Control Using Mixed Air Enthalpy, Jingjuan Feng, Mingsheng Liu, Xiufeng Pang

Durham School of Architectural Engineering and Construction: Faculty Publications

Enthalpy economizer can theoretically save more energy than temperature based economizer.  However, the requirement of outdoor air humidity measurement in the traditional enthalpy economizer control made it impossible.  A novel control sequence using mixed air enthalpy is developed in the paper.  Both theoretical and experimental investigation shows that humidity measurement in mixed air duct is very reliable, and the proposed method can achieve true enthalpy economizer saving.  A case implementation shows 15.7% more energy saving than temperature based economizer in Omaha, NE.

A Virtual Supply Airflow Rate Meter In Rooftop Air Conditioning Units, Daihong Yu

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Virtual sensing technology aims to estimate difficult to measure, expensive, or new quantities by using multifarious mathematical models along with non-invasive and low-cost measurements. Such embedded intelligence is a key to improving the performance of building systems in terms of functionality, safety, energy efficiency, environmental impacts, and costs. Considering the progress that has been achieved over many various fields (e.g., process controls, automobiles, avionics, autonomous robots, telemedicine) within the last two decades, numerous intelligent features have been incorporated and enabled that would otherwise not be possible or economical.

To identify the potential opportunities and research/development needs of virtual sensing technology …

A Novel Photovoltaic/Battery Structure For Solar Electrical Vehicles [Pvbs For Sev], Mahmoud Alahmad, Mohamed Amer Chaaban, Lana Chaar

Durham School of Architectural Engineering and Construction: Faculty Publications

In this paper, we propose a new flexible Photovoltaic/Battery charging Structure for Solar Electrical Vehicles (PVBS), where the interconnection of the system is dynamically changing based on current shading conditions across PV modules to provide intelligent system, as well as to provide flexibility, performance, and efficiency enhancement for the SEV. PVBS is expected to 1) provide a battery charging efficiency improvement over existing employed topologies; 2) provide new means to match the computing load with the PV system performance metrics shading and mismatches; 3) and provide elastic reconfigurable system expected to spur research advancements and innovations to make future SEV …

Lv-11-C031: Measured Levels Of Hospital Noise Before, During, And After Renovation Of A Hospital Wing, And A Survey Of Resulting Patient Perception, Cassandra H. Wiese, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Acoustic conditions in hospitals can negatively influence a patient’s physical and psychological health. This paperreports on noise levels measured before, during, and after renovation of a hospital wing in an Omaha, Nebraska, facility thatregularly receives unsatisfactory noise scores on patient satisfaction surveys. Sound pressure levels were logged every 10seconds over four-day periods in three different locations: at the nurses' station, in the hallway, and in a nearby patient’sroom. The resulting data have been analyzed in terms of A-weighted equivalent sound levels (LAeq) as well as variousexceedance levels (Ln). Results indicate that sound levels did not change much due to the …

Non-Intrusive Electrical Load Monitoring And Profiling Methods For Applications In Energy Management Systems, Mahmoud Alahmad, Hosen Hasna Hh, Evans Sordiashie

Durham School of Architectural Engineering and Construction: Faculty Publications

"Phantom Loads" cause energy waste in homes and the built environment as a whole. Consumers spend more than $3 billion a year on "Phantom Load" in the United States alone. The goal of this paper is to conserve energy by increasing consumer awareness on their energy usage and reducing and /or eliminating phantom loads in the built environment. A further goal is to improve upon existing power distribution systems in the built environment with limited hardware additions to increase energy conservation. This paper investigates remote identification of load types and the locations along the electrical circuitry where they (load) are …

Industry-Experienced Graduate Student Program: Innovative Collaboration In Architectural Engineering At The University Of Nebraska–Lincoln, Clarence E. Waters, Steve Alvine, Michelle L. Eble-Hankins

Durham School of Architectural Engineering and Construction: Faculty Publications

In 2001, the Architectural Engineering Department at the University of Nebraska–Lincoln, along with industry partners, established an industry-experienced graduate student program. The program was developed to bring experienced design professionals to collaborate with the industry while pursuing a Ph.D. in architectural engineering. This program is designed to be mutually beneficial to industry partners, -graduate students, the University of Nebraska–Lincoln Architectural Engineering Department, and the building industry at large. The first doctoral candidate in the program graduated, and significant collaborative work was completed for the industry partner. All parties to this initial offering are pleased with the outcome and believe the …

An Adaptive Photovoltaic-Inverter Topology, Mahmoud Alahmad, Mohamed Amer Chaaban, Siu Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

A new inverter topology for Adaptive photovoltaic (PV) system is proposed. An improvement in the power generation of the system during different operating conditions is achieved. The proposed configuration provides flexible connection between the PV modules and the inverters to meet current conditions of PV array. Preliminary simulation results are provided for an adaptive PV array. Efficiency comparison between traditional PV system configurations is discussed. Potential improvement using the proposed adaptive configuration is sited.

Combinatorics & Power Consumption, Mahmoud Alahmad, Wisam Nader

Durham School of Architectural Engineering and Construction: Faculty Publications

in this paper the power consumption possible combinations for a number of loads and a single power source are discussed. The proposed mathematical model depends basically on combinatorics to estimate how many ways are possible to operate different loads powered by a single power source. This paper takes into consideration the different conditions and limitations to operate n number of loads limited by their minimum and maximum values of power consumption. Four different cases of operations are discussed and modeled. A flowchart and a step-by-step method to do the calculations for a general case is also illustrated at the end …

Addressable And Energy Management System For The Built Environment (I), Mahmoud Alahmad, Hosen Hasna Hh, Evans Sordiashie

Durham School of Architectural Engineering and Construction: Faculty Publications

The increasing awareness for a cleaner earth has created more interests in the electric vehicle (EV) technology. Electric vehicles (EVs) will not only cause a reduction in our current greenhouse gas emissions, but also stop or reverse the trend at which our natural resources are being depleted. However, the introduction of the EVs into our societies will still require energy usage in the form of electricity. Integration of charging infrastructures will eventually be required in the built environment for these vehicles. This will add to the current energy consumption in the built environment which will mean more emission of CO2, …

The “Bim’S 4d+” Dimension: Real Time Energy Monitoring, Mahmoud Alahmad, Wisam Nader, Adam Brumbaugh, Yong Cho, Song Ci, Hamid Sharif, Jonathan Shi, Jill Neal

Durham School of Architectural Engineering and Construction: Faculty Publications

With the current trend towards Building Information Model (BIM), facility managers have a new tool for raising efficiency. This paper discusses the integration of the BIM software with a real-time monitoring (RTM) system, as a 4D+ dimension in BIM, to track the electrical usage at every location in a building. This ability could be invaluable in identifying what unnecessary loads are connected to a device and could be disconnected. This would result in elimination of needless loads and phantom loads during non-business hours, causing significant reduction in energy consumption. A prototype of the RTM was built and the results are …

Green And Sustainable Technologies For The Built Enviornment, Mahmoud Alahmad, Muhammad Zulfiqar, Hosen Hasna Hh, Hamid Sharif, Evans Sordiashie, Nasser Aljuhaishi

Durham School of Architectural Engineering and Construction: Faculty Publications

Energy conservation is among society’s greatest challenges, and the built environment has a concentrated impact on our natural environment, economy, and health. Fundamental understandings of how energy is consumed, monitored, and controlled are key prerequisites for an energy conservation process. This paper evaluates the effectiveness of real-time energy monitors (RTM) to influence behavior change in residential consumers. A methodology for remote identification of load types and the locations along the electrical circuitry where they (load) are being consumed is also presented. The load type and status (on, off, standby) are determined both remotely and in a non-intrusive manner using Non-Intrusive …

Optimization Of Energy Storage Systems In Hev's, Mahmoud Alahmad, Mohamed Amer Chaaban

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper introduces a novel battery model inspired by molecular structures mainly for applications in HEV’s. This novel 3-D adaptive battery topology shows potential for improvement in input and output performance as well as the charging/ discharging efficiency of batteries. The proposed topology provides flexible connections between battery cells to achieve different configurations of battery. A new switching matrix has been developed to achieve the required configurations. Preliminary simulations provide promising results for an adaptive 3-D battery configuration. Comparison between traditional battery configurations and the adaptive 3-D configuration is considered. A significant improvement in power curves is achieved by the …

Integrating Air Handling Units In Office Buildings For High Performance, Yuebin Yu

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

This study investigates the thermal load features in office buildings and proposes an innovative Integrated Air Handling Unit (IAHU) concept in order to achieve energy savings with conventional office building air handling systems. The corresponding deduction of IAHU for an acceptable Indoor Air Quality (IAQ) and better energy performance is conducted. The system variables and constraints are analyzed in detail to understand the feasibility and operability of IAHU. The control logics and implementation methods are elaborated for typical system layouts. With an IAHU operation, the internal heat gain can be transferred from an interior region into an exterior region in …

Industry Participation In The Interdisciplinary Team Design Project Course Of A Master Of Architectural Engineering Program, Lauren M. Ronsse, Lily M. Wang, Clarence E. Waters

Durham School of Architectural Engineering and Construction: Faculty Publications

This is a case study of extensive industry participation in the capstone design course of the Master of Architectural Engineering program at the University of Nebraska – Lincoln. This course, entitled Interdisciplinary Team Design Project, pairs teams of professional engineers and students to provide mentoring, assessment, and feedback, as the students work on interdisciplinary teams to design the building systems for a real-world project. For the spring 2010 semester, over 33 industry professionals participated in the course, each contributing approximately 40 to 50 hours of mentoring and assessment. This paper describes the course format and industry involvement, which provides students …

Investigation Of Patient Perception Of Hospital Noise And Sound Level Measurements: Before, During, And After Renovations Of A Hospital Wing, Cassandra H. Wiese

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Acoustic conditions in hospitals have been shown to influence a patient’s physical and psychological health. Noise levels in an Omaha, Nebraska, hospital were measured and compared between various times: before, during, and after renovations of a hospital wing. The renovations included cosmetic changes and the installation of new in-room patient audio-visual systems. Sound pressure levels were logged every 10-seconds over a four-day period in three different locations: at the nurses' station, in the hallway, and in a nearby patient’s room. The resulting data were analyzed in terms of the hourly A-weighted equivalent sound pressure levels (��_��eq) as …

Multi-Channel Orchestral Anechoic Recordings For Auralizations, Michelle C. Vigeant, Lily M. Wang, Jens Holger Rindel, Claus Lynge Christensen, Anders Christian Gade

Durham School of Architectural Engineering and Construction: Faculty Publications

Multi-channel orchestral anechoic recordings were obtained at the Technical University of Denmark (DTU) in June 2005. Every orchestral part of specific movements of two symphonies, Brahms’ Symphony No. 4, 3rd movement, and Mozart’s Symphony No. 40 in g minor, 1st movement, were digitally recorded using five 0.5” DPA microphones, with four surrounding the musicians in the horizontal plane and the fifth directly above. The recordings were made in DTU’s large anechoic chamber, which has free space of about 1000 m3 and a lower frequency limit of 50 Hz. Each musician was recorded individually, and to assist with overall synchronization of …

Examining The Relationships Between Monaural And Binaural Classroom Acoustics Parameters And Student Achievement, Lauren M. Ronsse, Lily M. Wang, Paul L. Sim

Durham School of Architectural Engineering and Construction: Faculty Publications

This study investigates the relationships between several classroom acoustics parameters and student achievement. Detailed binaural room impulse response measurements were conducted in four elementary school classrooms in a midwestern public school system in the United States. Unoccupied background noise levels were also recorded in these spaces. Previous studies have compared how different room acoustics metrics predict speech intelligibility, while another investigation examined perception-based binaural metrics in a typical classroom. This study extends these previous research areas by comparing both binaural classroom acoustics metrics and unoccupied background noise levels to each other and to the standardized student achievement scores of students …

Effects Of Building Mechanical System Noise On Worker Performance And Perception, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper presents results from a number of studies that investigated the effects of noise from building mechanical systems on human task performance and perception.  Three phases of research were conducted, each of which utilized a different set of noise signals produced by building mechanical systems: (1) broadband noise at different levels and spectral qualities; (2) tonal noise conditions; and (3) noise conditions with time-varying fluctuations.  In each phase, at least six different noise signals (many based on in-situ measurements) were reproduced in an office-like setting.  Thirty participants completed tasks (e.g. typing, grammatical reasoning, math) plus subjective questionnaires, while exposed …

Active Noise Barrier Minimizing Pressure Gradient, Carl Hart, Siu-Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

Minimization of the sound pressure field within the shadow zone of a noise barrier is achieved by reducing the pressure gradient along a line, at the top of a barrier, via active noise control. The noise control effectiveness of a barrier is increased by this strategy, especially for specific system configurations. The proposed method was evaluated by numerical simulation. Results indicate that system orientation has little effect on minimizing the pressure gradient at the top of the barrier when the error sensors are invisible to the primary noise disturbance. Highly effective control within the shadow zone and close to the …

Ab-10-C037: Effects Of Noise From Building Mechanical Systems On Elementary School Student Achievement, Lauren M. Ronsse, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This project seeks to determine what relationship, if any, exists betweenbackground noise levels in elementary classrooms due to the building mechanicalsystems and student performance on achievement tests. Previous research inclassroom acoustics has clearly identified that lower background noise levelsresult in higher speech intelligibility which is crucial for the learning process;however, there is a lack of data correlating lower noise levels to improved studentachievement scores. For this study, background noise level measurements were madein 14 elementary schools in a public school system in Council Bluffs, Iowa, USA.The measurements were made in unoccupied classrooms with the central buildingmechanical systems activated. Second and …

Optimum Absorption And Aperture Parameters For Realistic Coupled Volume Spaces Determined From Computational Analysis And Subjective Testing Results, David T. Bradley, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This project utilizes computational modeling to study the effects of varying two architectural parameters, absorption ratio and aperture size, in a realistic coupled volume concert hall. Coupled volumes have been shown to exhibit non-exponential sound energy decay profiles, referred to as double slope effect. A number of objective metrics (T30/T15, LDT/T10, decay ratio, and ΔL) have been used to quantify the double slope effect of the profiles generated in the virtual hall. T30/T15 and LDT/T10 showed similar trends across all hall configurations, indicating decreasing double slope effect with increasing coupled volume absorption ratio for each aperture size, and producing highest …

Ab-10-018: The Effects Of Noise From Building Mechanical Systems With Tonal Components On Human Performance And Perception (1322-Rp), Erica E. Ryherd, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This study investigated the effects of noise from building mechanical systems with tonal components on human task performance and perception. Six different noise conditions based on in-situ measurements were reproduced in an office-like setting; all were set to approximately the same sound level (47 dBA) but could have one particular tonal frequency (120 Hz, 235 Hz, or 595 Hz) at one of two tonal prominence ratios (5 or 9). Thirty participants were asked to complete typing, grammatical reasoning, and math tasks plus subjective questionnaires, while being exposed for approximately 1 hour to each noise condition. Results show that the noise …

Computational Modeling Of Effects Of Alloying Elements On Elastic Coefficients, Z. K. Liu, H. Zhang, S. Ganeshan, Y. Wang, S. N. Mathaudhu

Durham School of Architectural Engineering and Construction: Faculty Publications

Models for composition and temperature dependencies of single-crystal elastic stiffness coefficients are developed and applied to the Al₁₂Mg₁₇ and hexagonal closed-packed solution phases in the Mg–Al system based on data from first-principles calculations. In combination with models for multi-phases, the bulk, shear, and Young’s moduli of Mg–Al alloys are predicted and compared with available experimental data in the literature. It is noted that both phase transition and grain boundary sliding may play important roles in the elastic coefficients as a function of temperature.

Ab-10-017: Combined Effects Of Noise And Temperature On Human Comfort And Performance (1128-Rp), Dale Tiller, Lily M. Wang, Amy Musser, Matthew Radik

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper summarizes results from an experiment designed to investigate the combined effects of noise and temperature on human thermal comfort and task performance. Thirty subjects (16 females, 14 males) were exposed to all combinations of five thermal conditions (PMV +1 [79.6°F:26.4°C], PMV +0.5 [75.8°F:24.3°C], PMV 0 [72.1°F:22.3°C], PMV -0.5 [68.3°F:20.2°C], and PMV -1 [64.6°F:18.1°C]), three RC noise levels (RC-30, RC-40, and RC-50), and two sound qualities (neutral and rumbly): all sounds mimicked noise from building ventilation systems. After a one-hour adaptation period at each condition, subjects rated their thermal comfort using the ASHRAE Thermal Comfort Scale and the Tenant …

Ab-10-019: Human Performance And Perception-Based Evaluations Of Indoor Noise Criteria For Rating Mechanical System Noise With Time-Varying Fluctuations (1322-Rp), Lily M. Wang, Cathleen C. Novak

Durham School of Architectural Engineering and Construction: Faculty Publications

The goal of this study was to investigate the effects of noise from building mechanical systems with time-varying fluctuations on human task performance and perception, and to determine how well current indoor noise rating methods account for this performance and perception. Six different noise conditions with varying degrees of time-varying fluctuations, many focused in the low frequency rumble region, were reproduced in an office-like setting. Thirty participants were asked to complete typing, grammatical reasoning, and math tasks plus subjective questionnaires, while being exposed for approximately one hour to each noise condition. Results show that the noise conditions with higher sound …