Engineering topics

Davis, Robert G.

Publications and source records attributed to Davis, Robert G..

At least 19 records

DOE OSTI2024

Why Tunable? A Look at Schools Using Tunable Lighting

Between 2016-2019, Pacific Northwest National Laboratory (PNNL), documented two early pilot installations of tunable lighting in schools, supported by U.S. Department of Energy (DOE) Solid-State Lighting (SSL) program. These pilot installations were opportunities for the schools to become more familiar with the technology, save energy, and support teachers and students. Tunable lighting continues to be of interest, particularly in classrooms for students with disabilities. This case study looks at tunable lighting systems installed in classrooms at eight school districts across the U.S. since 2015, the earliest known installation.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2022

Lighting in Senior Care Centers: Comparing Tunable LED Systems to Conventional Lighting Systems in Four Senior Care Centers

This study was initiated to contribute to evidence-based practices for tunable light-emitting diode (LED) lighting upgrades in the future. The report summarizes Pacific Northwest National Laboratory (PNNL) evaluations of lighting conditions in four senior care centers in Wisconsin including energy savings analysis and non-image forming (NIF) response metric calculations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2021

Achieving Integrated Daylighting and Electric Lighting Systems: Current State of the Art and Needed Research

This paper presents the results of a multi-disciplinary scoping study, the goals of which were to see the seamless integration and application of light in buildings, regardless of source, that is purposely modulated to illuminate surfaces and designed in a way that is comfortable, healthy, pleasing, cost effective, and energy efficient. The scoping study was performed in order to set the stage for transforming the design and realization of lighting systems integration (daylight and electric). This, in turn, will support achieving the the U.S. Department of Energy’s (DOE) Building Technologies Office (BTO) long-term energy savings goals. Holistic lighting systems of the future should include components that are adaptable to change, resilient to disruption, and robust. The system of codes, standards, guidelines, and contracts employed to design and implement lighting systems should be structured to help them to flourish, rather than being barriers to realization. Finally, the research thrusts and mechanisms should be engaged with these goals in mind. While integrated lighting systems may reduce lighting energy use in buildings, a broader web of non-energy impacts affecting occupant’s overall health, comfort, and satisfaction may also guide technology investment goals when the entire lighting systems lifecycle is considered. Daylighting systems are separated from electric lighting systems, and both are characteristically detached from other systems such as safety, security, communications, and information systems. Being disconnected from the inputs and outputs of other building systems precludes the ability to acquire and utilize information about occupation, status of systems, and interior and exterior environmental conditions. The outcome of this separation is that the standard building is not fulfilling the potential for creating dynamic and holistic lighting for building occupants.

Davis, Robert G.↗

DOE OSTI2021

Examining Perceptual Luminance Uniformity of Simulated Luminaire Patterns

Luminaire luminance uniformity is an important aspect that can affect perceived lighting quality, discomfort glare, and efficacy. While several metrics have been proposed to characterize luminance uniformity, previous studies have shown that current metrics such as Max:Min or Avg:Min luminance ratios can be insensitive to important differences in luminance gradient that may affect perceived uniformity. In an attempt to resolve this issue, previous studies incorporated a contrast sensitivity function for the human eye based on spatial frequency, such as in the UHVS metric; however, this metric has not been comprehensively studied in relation to perceived uniformity ratings. The study presented in this paper aimed to examine the relationship between the UHVS metric and perceived uniformity ratings. Specifically, the study used a web-based questionnaire that presented simulated luminance patterns and asked participants to assess uniformity using a two-alternative forced-choice procedure. Responses were collected and analyzed from 94 participants. The results showed a significant correlation and relationship between the UHVS metric and perceived uniformity. However, comparisons between patterns that had similar UHVS and between patterns that had larger differences in UHVS did not yield consistent results. These results suggest that the UHVS metric might be used for general guidance but may warrant further studies to better understand its sensitivity and improve its alignment with perceived uniformity ratings.

Abboushi, Belal K.↗

DOE OSTI2021

The Effect of Spectral Resolution of Light Sources on Photopic and a-opic Quantities

There is a growing interest in including light source spectrum in advanced lighting software tools and simulations. Given that traditional lighting software tools have been used primarily for calculating photometric quantities, their simplifying assumptions may not be suitable for calculating other a-opic quantities. Commonly used simulation tools use three values to represent the three primary colors (red, green, and blue), but others have expanded the number of bands (i.e., the spectral resolution) to 9, 27, or 81 in an attempt to more accurately represent variations in light source spectrum and downstream spectrally-derived quantities. It remains unclear, however, to what extent spectral resolution affects calculated quantities. To address this gap, a numerical analysis was completed using a large spectral power distribution database (n = 1,302 light sources). Calculated illuminance, a-opic irradiance, luminous efficacy of radiation (LER), melanopic efficacy of radiation (MER), and melanopic to photopic (M/P) ratio were compared for spectral resolutions of 3 and 9 bands compared to a baseline of 81 bands. Across all examined lighting quantities, considerable errors—a mean absolute percent error of 18.4%—were found when using 3 band calculations. These were reduced to 4% for 9 band calculations. The errors varied by metric and light source type. The results suggest that the use of 9 bands can more accurately characterize performance of different light source types across a range of metrics compared to using 3 bands.

Abboushi, Belal K.↗

DOE OSTI2020

Evolving theories of change: Rethinking of the effects of office lighting on occupants

This paper proposes an overall theory of change that relates lighting in offices to a holistic view of human responses that contribute to the well-being of office workers. The theoretical model considers how variations in the four fundamental lighting attributes affect visual performance, visual environment, and non-image forming responses. It moves beyond these lighting to address how external factors that are may mediate the effects on the desired lighting related outcomes, which in turn determine the final impact on occupants. The model builds on prior conceptual models of lighting effects and informs design and research planning for office lighting. Ultimately, properly supported task performance can increase occupant motivation but by itself may not achieve the holistic desired impact. Lighting attributes that support a pleasant visual environment and appropriate non-image forming responses can more fully contribute to an occupant’s mood and overall well-being.

Collier, Jessica M.↗

DOE OSTI2020

Energy impact of human health and wellness lighting recommendations for office and classroom applications

The goal of this investigation was to evaluate potential energy impacts of circadian lighting design recommendations gaining attention in a variety of common applications such as offices and classrooms. The renewed focus on health along with advances in SSL technology capabilities has underscored that there is still much to learn regarding the relationship between light and human physiology. The energy implications of designing to address these possible physiological effects are not yet fully understood. Beyond the fact that the basic metric of luminous efficacy (lumens per watt) does not cover these other effects, the emerging science seems to indicate that addressing a holistic view of the human needs in most applications may mean a need for increased light and associated energy use by electric lighting systems. Within the two applications considered, lumen output, spectral characteristics, surface reflectance distribution and desk orientation were varied to explore the magnitude of potential effects. Meeting current IES illuminance recommendations did not satisfy existing EML and CS recommendations for any of the simulations. In some cases, satisfying circadian metric recommendations required average illuminance that was more than double IES recommendations, which may negatively impact lighting quality as well. Using results from 45 unique simulation conditions, it was estimated that lighting energy use may increase between 10% and 100% due to increased luminaire light levels used to meet circadian lighting design recommendations listed in current building standards such as WELL v2 Q2 2019, UL Design Guideline 24480, and CHPS Core Criteria 3.0.

circadian lighting, lighting simulation, solid sta↗

DOE OSTI2020

Lighting Control in Patient Rooms: Understanding Nurses’ Perceptions of Hospital Lighting Using Qualitative Methods

Here, this study differs in its methodological approach from previously published research by interpreting qualitative results against existing literature to understand how nurses conceptualize medical–surgical patient rooms as productive settings in relation to lighting, as well as the ways in which nurses believe these spaces could be enhanced for patient satisfaction. Content analysis was used to interpret themes emerging from nurses’ subjective responses to open-ended items. Three of the facilities had older, traditional lighting systems; one had a contemporary framework. A theme of environmental control over both overhead and task lighting emerged from data from all items. Although controllability was among the “best” lighting attributes, more refinement is necessary for optimal staff productivity and patient satisfaction. Daylighting was also considered to be among the best attributes. Control over light level via additional dimming capability for patients, as well as additional light sources, was prominent across the four hospitals. Unique to the more modern facility, trespassing of light was problematic for nurses considering the experiences of patients—even where modern models exist, more attention can be paid to the ways in which window shades, and light sources outside of rooms, penetrate spaces and affect users. Finally, the finding that nurses and patients desire greater control over the lighting in patient rooms is consistent with Ulrich’s theory of supportive design for healthcare and coincides with advances in lighting technology. Despite differences in the level of sophistication in lighting among the four facilities, control continues to be a primary concern for nurses.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2020

Nurses’ Satisfaction with Patient Room Lighting Conditions: A Study of Nurses in Four Hospitals with Differences in the Environment of Care

Lighting systems in patient rooms must balance energy efficiency concerns with the holistic needs of patients, families, and medical caregivers. This paper reports survey responses from 138 individuals working in medical-surgical units in four hospitals, with three of the hospitals having traditional lighting systems and the other hospital having a more contemporary lighting system. The results add to a growing evidence base on the effects of lighting on nurses’ job performance, job satisfaction, and overall perceptions of the environment, and provide evidence that innovative lighting approaches and technologies are worth considering as an investment by hospital administrators looking to improve employees’ and patients’ perceptions of the patient room environment. This knowledge is intended to help facility designers and managers incorporate nurses’ perspectives in their decisions, as well as to inform technologists and engineers developing future generations of lighting systems for patient rooms. These future systems will utilize solid-state lighting technologies, such as LEDs, and will provide new opportunities for adapting the intensity, distribution, and spectrum of light to better satisfy the holistic needs of patients and caregivers at different times of day or night.

Davis, Robert G.↗

DOE OSTI2020

Patient rooms transition: Contemporary makes way for the future

Recent advances in lighting research, technology and control systems are creating new opportunities to use lighting in healthcare facilities, particularly patient rooms, to improve everyday experiences for patients, visitors and staff. Healthcare facilities design has undergone shifts in thinking over the past 50 years, including the incorporation of more technology, and moving from an institutional appearance to a residential appearance, with biophilic elements. The Facilities Guidelines Institute defines the term environment of care as “those physical environment features in a health care facility that are created, structured, and maintained to support and enhance the delivery of health care”. Many attributes of the environment of care in existing hospital patient rooms, especially those built prior to 1990, reflect a focus on maximizing the efficiency of delivering medical care, sometimes without much attention to the impact of design on the experience of patients and guests.

Davis, Robert G.↗

DOE OSTI2019

Lighting Research Today: The More Things Change, the More They Stay the Same

Change. It is the one word that best characterizes the environment for lighting research, as well as for lighting technology, in recent years; and yet, beneath the change there is an enduring foundation upon which that research rests. A barrage of new technologies and tools for producing and measuring optical radiation has revolutionized the possibilities for creating and characterizing lighting systems and conditions, but understanding the application of these new technologies and tools builds on a legacy of established measurement methods and protocols. The discovery of a previously unknown photoreceptor has brought new excitement to lighting research and application, but this discovery exists within the context of a long history of applied psychological research in lighting.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2019

Lessons in the classroom

Article for the Lighting Design + Application publication of the Illuminating Engineering Society.

Davis, Robert G.↗

DOE OSTI2019

Evaluating Tunable Lighting in Classrooms: Trial LED lighting systems in three classrooms in the Folsom Cordova Unified School District (Supplemental Report)

This report summarizes the results from a trial installation of light-emitting diode (LED) lighting systems installed in three classrooms at Gold Ridge Elementary (GRE) School in the Folsom Cordova Unified School District (FCUSD) in Folsom, CA. FCUSD asked the Sacramento Utility District (SMUD) to help them explore potential benefits of tunable-white lighting systems for children with Autism Spectrum Disorder (ASD). SMUD responded by implementing a research project and invited Pacific Northwest National Laboratory (PNNL) to document the performance of the LED lighting systems as part of a GATEWAY evaluation. SMUD and FCUSD staff coordinated and completed the design and installation of the LED systems, and coordinated the collection of data from teachers, students, and parents, while PNNL evaluated the energy and photometric performance of the systems.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2019

SSL R&D Data Mining - Screening for Potential Field Validation Candidates

In 2019, Pacific Northwest National Laboratory conducted a review for the U.S. Department of Energy of the projects that have been awarded research and development (R&D) funding for the advancement of solid state lighting (SSL) technologies. The projects were reviewed with the intent of finding research that is now utilized in commercially available products and to identify potential field validation project candidates. This paper discusses the research approach as well as what we learned regarding the commercial availability of the technologies that were advanced with DOE R&D funding. PNNL reviewed 82 projects from the DOE-supported SSL R&D portfolio and identified 11 projects to evaluate for potential laboratory and field validations in commercial buildings. For these 11 projects, reports were reviewed and interviews were scheduled with principal investigators to discuss commercialization status. Six projects were identified as holding promise as field validation candidates; four are being commercialized, while the remaining two have products or systems using some of the advancements that were developed during the funding period.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2019

Luminaire dirt depreciation (LDD): Field data from several exterior lighting projects

Luminaire dirt depreciation (LDD) data were evaluated for seven luminaires from three different project sites in Philadelphia PA, Minneapolis MN, and Yuma AZ. In each case, the luminaires were removed from the installation, carefully packaged and transported to a photometric testing laboratory, and then tested in the “as-is” or dirty condition, cleaned, and re-tested. In terms of light output, the results showed that the IES RP-36-15 method for estimating LDD was applicable to the LED luminaires evaluated. General claims of lower levels of dirt deprecation (or higher LDD values) for LED luminaires than for luminaires using conventional light sources were not supported by the test data for the LED luminaires in these three projects. While the overall measured lumen depreciation due to accumulated dirt closely matched IES estimates for LDD, the data indicated that the accumulated dirt on the luminaires dramatically altered the luminous intensity distribution of the luminaires, with reductions in intensity of more than 25% at peak angles. These effects on luminous intensity distribution are not accounted for in IES LDD estimates.

Davis, Robert G.↗

DOE OSTI2018

Yuma Border Patrol Lighting Retrofit: Final LED System Performance Assessment of Trial and Full Installation

Along the Yuma Sector Border Patrol Area in Yuma, Arizona, the GATEWAY program conducted a trial evaluation in which the incumbent quartz metal halide area lighting was replaced with LED at three pole locations, and illuminance measurements were recorded initially and at 2500 hours, 5000 hours, 7000, and 11,000 hours of operation. Additionally, four second-generation LED luminaires installed as part of the full installation were evaluated initially and again after 4,000 hours of operation. While the initial energy, lighting quality, and maintenance benefits relative to the incumbent high-pressure sodium system were very satisfactory, the study raises important questions regarding the long-term performance of LED lighting systems in high-temperature environments.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2017

GATEWAY Demonstrations: Tuning Hospital Lighting: Evaluating Tunable LED Lighting at the Swedish Hospital Behavioral Health Unit in Seattle

The GATEWAY program evaluated a tunable LED lighting system installed in the new Swedish Medical Behavioral Health Unit in Seattle that incorporates color-tunable luminaires in common areas, and uses advanced controls for dimming and color tuning, with the goal of providing a better environment for staff and patients. The report reviews the design of the tunable lighting system, summarizes two sets of measurements, and discusses the circadian, energy, and commissioning implications as well as lessons learned from the project.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2017

Long-Term Evaluation of SSL Field Performance in Select Interior Projects

This GATEWAY project evaluated four field installations to better understand the long-term performance of a number of LED products, which can hopefully stimulate improvements in designing, manufacturing, specifying, procuring, and installing LED products. Field studies provide the opportunity to discover and investigate issues that cannot be simulated or uncovered in a laboratory, but the installed performance over time of commercially available LED products has not been well documented. Improving long-term performance can provide both direct energy savings by reducing the need to over-light to account for light loss and indirect energy savings through better market penetration due to SSL’s competitive advantages over less-efficient light source technologies. The projects evaluated for this report illustrate that SSL use is often motivated by advantages other than energy savings, including maintenance savings, easier integration with control systems, and improved lighting quality.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗