Clarence E. Waters

The performance of occupancy-based lighting control systems: A review

This paper reviews the literature on occupancy-based lighting control as a prelude to the application of sensor networks to building management. Many buildings include systems to detect occupancy and control building services. Current systems use single measurement points to detect occupancy, and there can be significant uncertainty associated with the measurement of occupancy. Long time delay and high detector sensitivity settings compensate for this uncertainty, but these diminish the savings that could be achieved with more accurate occupancy measurement. More effective control may be provided by more extensive sensing, using a network of occupancy sensors, and more extensive analysis of sensor data. The literature reviewed in this paper establishes the need for an investigation of the performance of sensor networks when used for lighting control.

VCP and UGR Glare Evaluation Systems: A Look Back and a Way Forward

Abstract We review the discomfort glare evaluation systems of the Illuminating Engineering Society of North America (IESNA), Visual Comfort Probability (VCP), and that of the International Commission on Illumination (CIE), Unified Glare Rating (UGR), as they apply to interior electric lighting. We provide an overview of the history and research behind them and an extensive bibliography. The current IESNA Handbook states that the VCP is very limited in applicability to modern lighting systems, and was validated for lensed fluorescent systems only. The CIEs UGR system has been shown to be a good predictor of human responses for lensed fluorescent systems. Recently, the CIE has proposed extensions to the UGR discomfort glare model, which are applicable to most modern lighting systems, including small, large, and complex systems. We provide a review of these extensions and the research behind them. There are many similarities between VCP and UGR and only minor differences, and so we recommend that research be undertaken to validate the UGRs extensions to small, large, and complex systems.

Estimation of induction motor equivalent circuit parameters from nameplate data

The induction motor equivalent circuit parameters are required for many performance and planning studies involving induction motors. These parameters are typically calculated from standardized motor performance tests, such as the no load, full load, and locked rotor tests. However, standardized test data is not typically available to the end user. Alternatively, the equivalent circuit parameters may be estimated based on published performance data for the motor. This paper presents an iterative method for estimating the induction motor equivalent circuit parameters using only the motor nameplate data.

Validating the application of occupancy sensor networks for lighting control

A new occupancy detection sensor network was developed, commissioned and installed in two private offices: data were collected to evaluate the utility of the sensor network for lighting control. Results show that there is considerable uncertainty associated with the determination of occupancy using measurements from a single detector in a space. A sensor network reduces uncertainty, because data from other detectors provides converging information that can be used to determine if a space is occupied. Sophisticated analysis techniques can be applied to the sensor network data stream to provide improved occupancy measurement and lighting control, compared to current systems.

An Assessment of High Dynamic Range Luminance Measurements with LED Lighting

Abstract This study investigates whether high dynamic range imaging (HDRI) can accurately capture luminance of a single light emitting diode (LED) chip within the luminaire. Two conventional methods of determining luminance—the use of a luminance meter with a close-up lens and deriving luminance from illuminance measurements, source area, and distance—of a single LED chip are compared to HDRI measurements. The results show that HDRI using a Canon EOS 7D camera, fitted with 28–105 mm lens and a neutral density filter (with less than 1% transmittance) combined in Photosphere compares very well to a luminance value determined with goniophotometer measurements and calculations. It provides confidence in the ability of HDRI to capture luminance of a single LED chip.

Use of Professional Industry Interaction to Enhance Engineering Education

AbstractThe Architectural Engineering Program at the University of Nebraska–Lincoln has benefitted from forming partnerships with professionals in the building design industry. These relationships have exposed students to industry professionals in various settings through the development of several architectural engineering programs. These programs give students firsthand, real-life learning experiences with the profession that many of them will pursue upon graduation to supplement their classroom instruction. In addition to the programs’ educational benefits, by involving industry in many facets of the academic program, networking experiences occur that benefit students by helping them to find future jobs and benefit employers by helping them to develop an understanding of the abilities of certain students prior to the recruitment process. Industry professionals interact with students in various ways, including providing graduate students with project advice, forming teaching partnerships, and participat...

Electrical Distribution Systems for Commercial Reference Building Models

AbstractCommercial and residential buildings consume approximately 40% of the total energy in the United States and use approximately 70% of the electricity. The electrical energy efficiency of the buildings sector thus plays a vital role in reducing energy use, peak demand, and greenhouse gas emissions. Maximizing the efficiency of electricity use is a key priority for high-performance buildings; however, to date, electrical distribution systems have received little attention. Rather, the focus has been on broad categories of end-use devices. As a result, a relatively small body of literature relates to the energy efficiency of electrical distribution in commercial buildings. Understanding this system and its components will help us examine its efficiency in significantly more detail. This paper describes the determination of an electrical distribution system for a commercial reference building model (CRBM). The purpose of the CRBM project was to develop standard or reference building energy models for t...

Industry-Experienced Graduate Student Program: Innovative Collaboration in Architectural Engineering at the University of Nebraska, Lincoln

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 benefits significantly outweigh the costs. This paper presents the program, lessons learned, and plans for the future. The authors are the faculty, the industry partner, and the graduate associated with this initial application of the program.

Discomfort Glare from Small, High-Luminance Light Sources When Viewed against a Dark Surround

ABSTRACT This research examined human subjective responses to small, high-luminance light sources against low-luminance backgrounds and evaluated performance of four discomfort glare models. Forty-seven observers evaluated 36 conditions including three glare source luminances (20,000, 205,000, 750,000 cd/m2), two source positions (0°, 10°), two source sizes (10−5, 10−4 sr), and three background luminances (0.03, 0.3, 1 cd/m2) on a seven-point rating scale of perceived glare. The Unified Glare Rating (UGR) small source extension had the highest correlation with subjective responses (r = 0.879, P < 0.0001) within the ranges of the variables tested. This study validates and extends the UGR small source extension, typically used in interior spaces, to dark surrounds (for example, outdoor nighttime environments).

A need for evidence-based and multidisciplinary research to study the effects of the interaction of school environmental conditions on student achievement

Green or high-performance buildings have been a topic of much discussion and research in the architectural engineering community since the 1990s.Of interest is the potential positive environmental impact when compared to standard building construction, as well as the belief that the indoor environments of such buildings can positively impact occupant comfort, performance and health. However, evidence-based research on claims of improving occupant outcomes is rather limited. Certain aspects of the built environment, including indoor air quality, thermal, lighting and acoustic conditions, have been linked to human comfort and performance, but only in a limited fashion as is apparent from the literature review provided in ASHRAE Guideline 10 ‘Interactions Affecting the Achievement of Acceptable Indoor Environments’. Furthermore, the majority of studies cited in this ASHRAE guideline have investigated the effects of only one or two human-comfort-related environmental variables at a time, without considering how the multitude of environmental variables may interact with each other. Nor do they consider how human behaviour may adapt in an integrated environment. Rigorous research on how green or high-performance schools in particular may impact the performance and/ or health of students and teachers is also not extensive. Previous studies in this area can generally be categorised as two types: those that have relied on subjective surveys of the built environment, rather than physical objective measurements and those that have focused on a relatively small number of samples with periodic physical measurements. Examples in the former group include Earthman et al., Hines, Durán-Narucki. Results from these studies using opinion-based surveys do indicate improved student outcomes with better built environments, but unfortunately often cannot provide accurate predictions of that relationship. Investigations in the latter group tend to focus on only one or two aspects of the built environment; Schneider and Baker and Bernstein provide reviews of such work. Although some do find relationships between building attributes (e.g. the indoor air quality, thermal, lighting, or acoustic conditions) and improved academic outcomes, too many draw conclusions from indirect measures (health or performance through absenteeism, for example), from ill-designed experiments with a lack of statistical rigour, or from anecdotal evidence. With funding from the U.S. Environmental Protection Agency’s (EPA) Healthy Schools initiative, a research team from the University of Nebraska– Lincoln (UNL) is currently working on establishing how environmental conditions in K-12 school buildings impact student scholastic achievement. The objectives of the research project are: (1) to study comprehensively the impacts of a wide set of indoor environmental factors (including indoor air quality, thermal, lighting and acoustic conditions) on student achievement; (2) to investigate how these environmental conditions interact with each other to impact student achievement; (3) to rank order the environmental variables in terms of their relative impact on student achievement and (4) to determine how these effects vary with different demographic (e.g. socio-economic) groups.