TASK-AMBIENT LIGHTING: A SUSTAINABLE DESIGN METHOD INVESTIGATION by NICHOLAS A. CATON B.S., Kansas State University A REPORT submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Architectural Engineering and Construction Science College of Engineering KANSAS STATE UNIVERSITY Manhattan, Kansas 2007 Approved by: Major Professor Raphael Yunk Copyright NICHOLAS A. CATON 2007 Abstract Today’s engineers of building lighting systems must maintain a careful balance between the demands of accepted standards of practice, the necessity of life safety, the system performance needs of the client, and the developing national energy standards and certifications gaining prominence in the public eye. These sources of influence on the design process can create conflicts between the pressing need to conserve system energy usage and a costlier and perhaps unacceptable end-result for the client. In this climate, various governmental organizations and industry cooperatives have been funding published research and case-studies in order to promote sustainable design practices. Within these publications are repeated references to a “Task-Ambient” lighting fixture layout strategy. Multiple recent publications cite profound energy-saving benefits attainable using this design method. However, there is a noticeable lack of measured data concerning other qualities of this layout scheme, such as the end-user’s comfort and ability to perform tasks under the resulting light distributions. Whether this lack of data resulted from the added complexity associated with such non-numerical measurements, or for some other unknown reason, this report explores this gap in the available data. An extended survey procedure was developed to approach the problem of measuring these unknown qualities of the Task-Ambient design strategy. This involved constructing multiple physical lighting layout mockups, defining the features of the Task-Ambient strategy which necessitated measurement, and designing objective tasks tailored to measure each of these non- numerical qualities. The careful analysis of this study’s data results yields trends indicative of the Task-Ambient strategy, relative to a standard uniform layout, adversely affecting productivity, concentration, and the participants’ subjective perceptions of the space’s light distribution. The lowered level of energy use was however affirmed. The implications of these results are that the Task-Ambient strategy, while an efficient method of lighting system layout design, may not be beneficial for the client in other respects. Table of Contents List of Figures................................................................................................................................vi List of Tables...............................................................................................................................viii Acknowledgements........................................................................................................................ix Dedication.......................................................................................................................................x CHAPTER 1 - DISCUSSION........................................................................................................1 1.1 Scope.....................................................................................................................................1 1.2 Why research this?................................................................................................................1 1.2.1 Conflicts: Energy Codes vs. Safety vs. System Performance........................................2 1.2.2 Sustainable Design.........................................................................................................2 1.2.3 Psychometrics and Evaluation of Lighting Design........................................................3 CHAPTER 2 - THE TASK-AMBIENT LAYOUT STRATEGY..................................................5 2.1 What is Task-Ambient?........................................................................................................5 2.2 The Need for a Case Study...................................................................................................9 2.3 Hypotheses..........................................................................................................................11 CHAPTER 3 - TASK-AMBIENT CASE STUDY......................................................................12 3.1 Preparation for the Case Study...........................................................................................12 3.1.1 Defining What is Being Measured...............................................................................12 3.1.2 Methods of Measurement............................................................................................12 3.1.2.1 Concentration........................................................................................................12 3.1.2.2 Productivity...........................................................................................................13 3.1.2.3 Installation and Operating Energy Costs..............................................................13 3.1.3 Isolating the Layout Variable.......................................................................................14 3.1.4 Location.......................................................................................................................16 3.1.5 Selecting Survey Participants......................................................................................17 3.1.6 Establishing Procedure.................................................................................................18 3.2 Established Lighting Layouts.............................................................................................19 3.2.1 Lighting Layout #1 – Uniform, 50fc............................................................................19 3.2.2 Lighting Layout #2 – Task-Ambient...........................................................................21 iv 3.2.3 Lighting Layout #3 – Uniform, 30fc............................................................................22 3.3 Case Study Data and Discussion........................................................................................23 3.3.2 Reading Task Data.......................................................................................................26 3.3.3 Survey Results.............................................................................................................29 3.3.4 Installation and Operating Cost Data...........................................................................30 CHAPTER 4 - SUMMARY.........................................................................................................33 4.1 Summarized Case Study Conclusions................................................................................33 4.2 Closing Thoughts................................................................................................................33 4.3 Future Study Improvements................................................................................................34 Works Cited..................................................................................................................................36 Software Cited..............................................................................................................................39 Appendix A - Survey Materials....................................................................................................40 Appendix B - Lighting Layout Establishment Information..........................................................56 Appendix C - Photographs............................................................................................................62 Appendix D - Survey Data............................................................................................................73 Appendix E - Cost-Comparison Calculations and Data...............................................................77 Appendix F - Committee for Research Involving Human Subjects Documentation....................85 v List of Figures Figure 2.1 Uniform vs. Task-Ambient Layout Strategy.................................................................6 Figure 2.2 Visual - Lighting Design Software................................................................................9 Figure 2.3 Uniform vs. Task-Ambient Comparison (“Energy Design Resources” 5)..................10 Figure 3.1 The Kansas State Lighting Lab – Room S223A.........................................................16 Figure 3.2 50fc Uniform Lighting Lab Mockup...........................................................................19 Figure 3.3 Task-Ambient Lighting Lab Mockup..........................................................................21 Figure 3.4 30fc Uniform Lighting Lab Mockup...........................................................................22 Figure 3.5 Average Math Scores..................................................................................................24 Figure 3.6 Math Productivity Scores – Individual Results...........................................................25 Figure 3.7 Average Reading Scores..............................................................................................26 Figure 3.8 Reading Accuracy Scores – Individual Results...........................................................27 Figure 3.9 Math Accuracy Scores – Individual Results...............................................................28 Figure 3.10 Average Survey Results............................................................................................30 Figure A.1 Alphanumeric Designation (blue sheet).....................................................................41 Figure A.2 Survey Guidelines and Procedure (blue sheet)...........................................................42 Figure A.3 IRB-required Informed Consent Document...............................................................43 Figure A.4 Task A – Algebra Marathon (1 of 3)..........................................................................44 Figure A.5 Task B – Reading Comprehension Passage(s) (1 of 3)..............................................45 Figure A.6 Task B – Reading Comprehension Answers (1 of 3).................................................46 Figure A.7 Survey Form (green sheet) (1 of 3)............................................................................47 Figure A.8 Algebra Marathon (2 of 3)..........................................................................................48 Figure A.9 Task B – Reading Comprehension Passage(s) (2 of 3)..............................................49 Figure A.10 Task B – Reading Comprehension Answers (2 of 3)...............................................50 Figure A.11 Survey Form (green sheet) (2 of 3)..........................................................................51 Figure A.12 Algebra Marathon (3 of 3)........................................................................................52 Figure A.13 Task B – Reading Comprehension Passage(s) (3 of 3)............................................53 Figure A.14 Task B – Reading Comprehension Answers (3 of 3)...............................................54 vi Figure A.15 Survey Form (green sheet) (3 of 3)..........................................................................55 Figure B.1 Sample Uniform Lighting Level Estimation Calculation...........................................56 Figure B.2 Determining the number of measurement points for a Uniform Grid........................57 Figure C.1 50fc Uniform Lighting Layout...................................................................................63 Figure C.2 30fc Uniform Lighting Layout...................................................................................64 Figure C.3 Task-Ambient Lighting Layout..................................................................................65 Figure C.4 The Kansas State Department of ARE and CNS Lighting Lab..................................66 Figure C.5 Robert Nelson properly taking a footcandle reading on the task plane......................67 Figure C.6 Recording of Mockup Illuminance Data....................................................................68 Figure C.7 Elimination of Fenestrations and External Light Sources..........................................69 Figure C.8 Typical Obscuration Method for Undesired Fixtures.................................................70 Figure C.9 Motorized Blinds along Lighting Lab West Wall......................................................71 Figure C.10 Identification of Contaminate Light Sources............................................................72 Figure E.1......................................................................................................................................78 Figure E.2......................................................................................................................................80 Figure E.3......................................................................................................................................81 Figure E.4......................................................................................................................................82 Figure E.5......................................................................................................................................83 Figure E.6......................................................................................................................................84 Figure F.1 IRB Application for Approval Form and required attachments (14 pages)................86 vii List of Tables Table 3.1 Lighting Layout Comparative Cost Analysis...............................................................31 Table D.1 Raw Math Task Data...................................................................................................74 Table D.2 Raw Reading Task Data...............................................................................................75 Table D.3 Raw Survey Data.........................................................................................................76 Table E.1.......................................................................................................................................79 viii Acknowledgements This Masters research and report was enhanced by the contributions of a large number of individuals. I feel very thankful for the time, knowledge, and generosity offered by these people, and would like to acknowledge their contributions. Robert Nelson devoted many hours of his own time during his final, graduating semester in the department to assist me in the preparation and execution of the survey research. His presence was invaluable not only for the time he put in, but also his invaluable contributions as a wall to bounce my ideas off of. Tim Dieker, a former department instructor, offered particularly in- depth guidance, extended loans of texts and guides from his personal library, instrumental assistance with the operation of the KSU lighting lab features and controls, and also deserves credit for getting me interested in the fields of power and lighting systems design to begin with. I would also like to thank Doug Harwood of Mercer-Zimmerman, a lighting fixture manufacturers’ representative in Topeka, Kansas, for his timely and thorough input regarding fixture pricing for the economic comparison in this report. A number of other graduate students and faculty throughout the campus also offered their input, suggestions, and experiences – collectively assisting me as much as any other individual. In no particular order: • Carolyn Delandre • Dane Pletcher • John Tomich • Tate Betz • Nozomi Matsumiya • Eric Domingo • Lisa Meyer • Clare Seip Finally, perceptive and constructive criticisms in all stages of this endeavor, from initial research of the problem through the final analysis of the data and polishing of this physical report, came from the graduate committee members from my department: Raphael Yunk, Julia Keen and Chuck Burton. All of these individuals went well beyond the call of duty in guiding and assisting me through the entire process. A better team of mentors couldn’t be asked for, and if I could go back and reconstruct my “dream team” of advisors I wouldn’t have changed a thing. ix Dedication I would like to dedicate this work to my father – Tony Mark Caton. He passed away for medical reasons in his early thirties as a Major in the United States Army. This happened before he could see me finish middle and high school, before he could see me accepted into college, before he could have met the fiancé I met there and before he could witness my completion of a minor, bachelors and masters degree in engineering. There have been many moments I would like to have shared with my father in this time span. He was an outstanding person, who shaped my character and values in a way I aspire to one day do for my own children. I occasionally wonder, even in these happiest times, what advice he would give, or what he might think of the decisions I make. I like to think that with this report, and at this stage of my life, my father would have been very proud and happy. x