Assessing Disability Glare Potential Due to Reflections...

Jakubiec, J. A. and C. F. Reinhart 1 Submitted to the 2014 Annual Meeting of the Transportation Research Board.

Assessing Disability Glare Potential Due to Reflections from New Constructions: A Case Study Analysis and Recommendations for the Future

J. Alstan Jakubiec(*,♦) and Christoph F. Reinhart(**)

* E-Mail: [email protected] Department of Architecture, Massachusetts Institute of Technology 77 Massachusetts Ave, Rm 5-418 Cambridge, MA 02139, USA Telephone: (912) 247-1086, Fax: (617) 253-6152

** E-Mail: [email protected]

Department of Architecture, Massachusetts Institute of Technology 77 Massachusetts Ave, Rm 5-418 Cambridge, MA 02139, USA Telephone: (617) 253-7714, Fax: (617) 253-6152

♦ Corresponding Author


ABSTRACT Disability glare, visual impairment due to extreme brightness or contrast, can be caused by intense

reflections from new constructions nearby existing transportation or building infrastructure. A case study analysis is performed of a disability glare hazard at an airport created by the installation of a large array of photovoltaic panels between an air traffic control tower and the aircraft taxiway. The panels reflect blinding quantities of daylight into the control tower, produce temporary after images and dangerously obscure taxiing aircraft. The existing FAA guidelines for installation of solar technologies are discussed relative their shortcomings in identifying the glare hazard.

High dynamic range photography is used to analyze the glaring situation at the airport, and the authors propose a maximum brightness threshold of 30,000 cd/m2 based on the physiology of human vision and the brightness of tasks necessary for air traffic controllers at the case-study airport. Detailed reflectivity and three-dimensional models of the photovoltaic panels and the airport are created and validated against measured data. Using these models, an annual analysis is performed of the glare hazard. This analysis is displayed temporally using graphs and spatially using images that indicate where the glaring reflections originate. Such information is useful in identifying the potential for disability glare before new constructions are built. Finally, the authors use the new method to analyze designs for remediation of the glare hazard.

INTRODUCTION

New constructions such as photovoltaic (PV) panels or buildings can cause glare due to intense reflections of sunlight from their surfaces. Such reflections can literally occur in blinding quantities, preventing occupants from performing tasks. This effect is known as disability glare. Disability glare measurably impairs vision, reducing the contrast of the retinal image by the presence of a very bright light source in the field of view (1). To remedy such issues after construction is expensive, and those affected must tolerate the glare until the problem is remedied. In order to address the issue of glare hazards from new constructions, this paper presents a general method for analyzing glare hazards based on three-dimensional (3D) models produced during the design phase, measured material properties and physically accurate lighting simulations.

The new method is presented through a case study analysis of glare at an airport caused by intense reflections from a PV array consisting of 2,478 panels located between the airport’s air traffic control tower (ATCT) and an airplane taxiway. Specular reflections from the PV array are so extreme that they prevent the visibility of aircraft on the taxiway and cause temporary after images that impede the viewing of computer monitors inside the ATCT. As such, the reflections at the case-study airport meet the qualifications to be considered disabling.

The PV array was analyzed according to Federal Aviation Administration (FAA) best practice guidelines for the installation of solar technologies prior to its construction; however, the original analysis did not detect the glare hazard. Thus, there is a need to define a clear process through which to conduct glare prediction analysis that is useful during the design of new constructions that have the potential reflect large quantities of daylight. A case study approach is taken to address this need through an analysis of the airport’s glare problem. First, a review of existing methods for analyzing glare from specular surfaces is conducted. Following that, the authors reproduce the problem in a physically-based daylighting simulation software capable of predicting reflections from new designs before they are constructed and outline steps necessary to reproduce our method. The simulations use physically accurate material models that account for specular and diffusing reflective surface properties of PV panels. Side-by-side comparisons of high dynamic range (HDR) photographs and the authors’ physically-based renderings confirm the accuracy of these models. Next, an annual analysis is conducted using a ten-minute simulation interval for every daylit hour in the year. Following this, the likelihood of experiencing disability glare is displayed spatially and temporally in order to understand the time, location and intensity of potential glaring reflections. Finally, the new method is used to analyze proposed remediation strategies of the disability glare problem at the case-study airport.

Jakubiec, JSubmitted to

QUALIFY Disability

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Dynamic Range of Human Vision To assess the impact bright specular reflections have on perception, considering the physiology of human

vision is critical. The eye is a logarithmic sensor capable of perceiving 12 log units of luminance; however, human vision is only capable of resolving a portion of the luminous scale at any given time based on the visible luminous environment (3). Specifically, the adaptation luminance is the brightness level the eye is adapted to that determines what range of the luminous scale is perceivable.

Ferwerda, et al. suggest that the adaptation luminance should be half the value of the highest perceived luminance, which will vary depending on the outside brightness, solar position, and reflectivity of glare-inducing surfaces (4); however, this works primarily for normal viewing conditions where the sun and glaring reflections are not present. In the case of disability glare analysis where the task is known, it makes sense to choose the adaptation luminance relative to the desired tasks. From Figure 1, focusing on the monitor (255 cd/m2), is the lowest task luminance level, which is reasonable considering the luminous range of a typical computer monitor is between 10 and 300 cd/m2. The highest task luminance level is focusing on the taxiway (8,901 cd/m2).

Generally, the human eye can recognize between two and three orders of magnitude of luminance variation at any time (3). Taking the mean brightness of the two task luminances, approximately two orders of magnitude of luminous difference can be visualized (3, 5). This means that in order to view planes on the taxiway while maintaining the ability to read the monitor, luminance levels in the line of sight would need to be less than 30,000 cd/m2 observing these two orders of magnitude as a rule. Therefore the authors propose a brightness of 30,000 cd/m2 as a threshold at which the probability of experiencing disability glare is likely. The measured value of 250,000 cd/m2 from the PV panels in Figure 1 is well above this threshold. Air traffic controllers attempting to view the runway experience after images and are prevented from visually identifying aircraft on the taxiway. Although the sky is very bright and often above 30,000 cd/m2, the operable shades present in the ATCT can be used to block the brightness of the sky; however, they cannot be lowered to obstruct the PV array without also blocking the taxiway. Until the glare problem is remedied, the airport is covering the PV array with tarps, which prevent disability glare but have the side effect of also preventing the generation of electricity.

Existing Disability Glare Metrics from Specular Reflections

The FAA defines interference from solar panels concerning airspace penetration, reflectivity, and communication systems interference (6). As this analysis relates to visual disability, the authors are concerned with the regulations dealing with reflectivity. All solar installations at airports must include an “assessment of reflectivity including time periods when reflection may contact [the ATCT] and aircraft.” The FAA provides three methods of analyzing potential glare problems:

1. A qualitative analysis of potential impact in consultation with [air traffic control staff], pilots, and airport officials,

2. a demonstration field test with solar panels at the proposed site in coordination with FAA Tower personnel or,

3. a geometric analysis to determine days and times when an impact is predicted. Method 1 is potentially inadequate as the involved parties may not have the experience or the ability to

assess the potential glare hazards involved with the proposed PV system; however, it is probably adequate when PV panels will be installed far away from any critical visual areas. Method 2 is inadequate as the field test is performed during a single moment; however, the sun changes its position in the sky throughout the entire year. A test at a single time may miss glare hazards during other parts of the year. Method 3, geometric analysis, could analyze potential glare hazards throughout the year; however, there is currently no guidance on its implementation beyond two example figures that portray a perfectly specular reflection at four times during the year as if from a mirror. Such an analysis ignores potential glaring reflections during other times of the year. More importantly, a purely geometric analysis neglects the true behavior of reflected light from PV panels. Such an analysis could miss identifying potential glare hazards where an analysis that considers forward-scattering when daylight is reflected would not.

Ho et. al propose a geometric analysis method that accounts for diffuse and specular reflective properties as well as the form of a reflecting surface in order to assess glare hazards (7). The result of their geometric calculation is evaluated based on irradiance at the retina and the size of the glaring source. It is based on previous research on the physiology of the human eye to experience after images and retinal burning. The method is useful for detecting problems and quickly iterating through solutions; however, it does not provide spatial feedback regarding where the glare originates from at any given time.


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explored. By ffic operators. Iing annual ting the PV pan

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9

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less ease is ugh to

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CONCLU

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FIGURE 7

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ons that use spee for the specuwith a large amor of physical rvalue of 30,00

ms beyond thathe analysis of

An issue identifting Selected Sr the physical rt the year. Hadkely would hav

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materials. In ordents (14) need e used in critic


s. To reinforce ATCT (5x10-2

paths to the exher, the potentie PV panels.

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illustrates the pecular material

ular surfaces of mount of glazinreflections whe00 cd/m2 in theat threshold whf an airport withfied in this studSolar Technoloreality of reflec

d the analysis mve been identif

arrier to such ant nearly impossder for meaningto be performe

cal situations.

nsportation Resea

what this 2% m2 sr). When comxisting visibilityial for air traffi

y of rotated PV

ed PV panels fginal visibilityvisible area of

potential for phls in critical sitf PV panels; hong or bodies of en using appro

e line of sight hhen also viewinh a known disa

dy is that the anogies on Airporctions from PV

method proposefied before connalysis is that msible to compargful analysis toed and made av

arch Board.

means, Figure mparing PV viy of PVs from ic controllers to

V panels from a

from airplane ly of PV panels f PV in steradia

hysically-baseduations such a

owever, it is alswater. The aut

opriately calibrahas been proposng a typical comability glare prnalysis guidelinrts” document

V panels or thated in this studynstruction. measured matere the benefits o be made in thvailable for a w

7b adds an extisibility, the mathe ATCT, the

o experience g

airplane landin

landing paths cfrom the ATCan from the AT

d renderings tos at airports. Tso appropriate thors have showated material msed based on thmputer screen.roblem. nes proposed inare vague and t does not acco

y or that of Ho,

erial data from of choosing be

he future, detaiwide variety of

tra data point, taximum possibere is very littl

glare is now zer

ng paths.

compared againCT. TCT and landin

o analyze propoThe new method

for other constwn that simula

models. A newhe physical abiThis upper lum

n the FAA’s “Tallow analysis

ount for differin, et al. been uti

PV panels is laetween differeniled angular-def potential cons

the current visible glaring refle potential for ro as they only

nst

ng paths.

osed new d of analysis istructions such ations closely m

w maximum visility of the eyeminance limit w

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10

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After using a HDR photographic method to derive angular-dependent material reflection data, the authors undertook an annual analysis of the case-study airport with a known occurrence of disability glare. The new method produces charts (Figure 4) that illustrate the time and intensity of glaring reflections and images (Figures 5 and 6) that show the location of glaring reflections. Such results allow intuitive design changes based on observations. For example, Figure 5 suggests that a more northern site for the PV array would have been beneficial. The authors’ new method was used to analyze two proposed remediation strategies. This analysis found that a material solution using a less-reflective PV panel was not viable in this case, but that a geometric solution to rotate the PV panels would remedy the glare hazard.

REFERENCES

1. Commission Internationale de l’Eclairage. Discomfort Glare in Interior Lighting. CIE Publication 117, 1995.

2. Inanici, M. N. Evaluation of High Dynamic Range Photography as a Luminance Data Acquisition System. Lighting Research and Technology, Vol. 38, No. 2, 2006, pp. 123-34.

3. Boyce, P. R. Human Factors in Lighting, Second Edition. Taylor & Francis Inc., New York, 2003. 4. Ferwerda, J. A, S. N. Pattanaik, P. Shirley, and D. Greenberg. A Model of Visual Adaptation for Realistic

Image Synthesis. Proceedings of ACM SIGGRAPH '96, pp. 249-58. 5. Hopkinson, R. G. and J. B. Collings. The Ergonomics of Lighting. Macdonald & Co., 1970. 6. Federal Aviation Administration, Office of Airports, Office of Airport Planning and Programming,

Airport Planning and Environmental Division (APP-400). Technical Guidance for Evaluating Selected Solar Technologies on Airports. http://www.faa.gov/airports/environmental/policy_guidance/media/airport_solar_guide.pdf. Accessed May 9, 2013.

7. Ho, C. K., C. M. Ghanbari and R. B. Diver. Methodology to Assess Potential Glint and Glare Hazards from Concentrating Solar Power Plants: Analytical Models and Experimental Validation. Journal of Solar Energy Engineering, Vol. 133, No. 3, 2011.

8. Ward, G. J. The RADIANCE Lighting Simulation and Rendering System. Proceedings of the 21st Annual Conference on Computer Graphics and Interactive Techniques, 1994, pp. 459-72.

9. Reinhart, C. F. and M. Andersen. Development and Validation of a Radiance Model for a Translucent Panel. Energy and Buildings, Vol. 38, No. 7, 2006, pp. 890-904.

10. Mardaljevic, J. Validation of a Lighting Simulation Program Under Real Sky Conditions. Lighting Research and Technology, Vol. 27, No. 4, 1995, pp. 181-8.

11. Reinhart, C. F. and O. Walkenhorst. Validation of Dynamic RADIANCE-based Daylight Simulations for a Test Office with External Blinds. Energy and Buildings, Vol. 33, No. 7, 2001, pp. 683-97.

12. Reinhart, C. F. and P. F. Breton. Experimental Validation of Autodesk® 3ds Max® Design 2009 and Daysim 3.0. Leukos, Vol. 6, No. 1, 2009.

13. Ibarra, D. and Reinhart, C. F. Solar Availability: A Comparison Study of Irradiation Distribution Methods. Proceedings of Building Simulation 2011: 12th Conference of International Building Performance Simulation Association, 2011, pp. 2627-34.

14. Apian-Bennewitz, P. and J. von der Hardt. Enhancing and Calibrating a Goniophotometer. Solar Energy Materials and Solar Cells, Vol. 54, No. 1, 1998, pp. 309-22.

15. PAB Advanced Technologies, Ltd. BME BSDF Data. http://www.pab.eu/gonio-photometer/demodata/bme/ward_metal_ps.anofol606.37.385/index.html. Accessed July 1, 2013.

16. Ashikhmin, M. and P. Shirley. An Anisotropic Phong BRDF Model. Journal of Graphics Tools, Vol. 5, No. 2, 2000, pp. 25-32.

17. Ward, G. What’s New in Radiance for 2013. http://www.radiance-online.org/community/workshops/2012-copenhagen/Day2/Ward/RadianceImprovements.pdf. Accessed January 15, 2013.

18. Commission Internationale de l’Eclairage. Spatial Distribution of Daylight - CIE Standard Overcast Sky and Clear Sky. CIE Publication S003, 1996.

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