11/14/2016 Exponation AIA Provider Number: 70119700 Meters, - PDF document

11/14/2016 Exponation AIA Provider Number: 70119700 Meters, Metrics and Visual Perception LEDSSMW16-S#1 Kevin Willmorth, Lumenique LLC and Tasca 11.15.16 Credit(s) earned on completion of This course is registered with AIA this course will be reported to AIA CES for continuing professional CES for AIA members. education. As such, it does not Certificates of Completion for both include content that may be AIA members and non-AIA deemed or construed to be an members are available upon approval or endorsement by the request. AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. _______________________________________ Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. Course Learning Description Objectives This presentation will explore the issues ● 1. Understand the use of metrics and their of metrics, meter use and the connection limitations, and how to use them to solve real world issues, while avoiding assumptions about them that and disconnect these have with actual lead to issues in application. visual results. The exploration includes ● 2. Understand how meters used to evaluate presentation of a concept for a more products and field results work, where they can be complete metric representation of lighting relied upon, and when they produce unreliable data. qualities, the combines uniformity, color Includes presentation of simple strategies for gaining and visual qualities. the best meter results, and what meters on the market today can do for designers. ● 3. Gain insight into the potential of creating a new metric tool for evaluating products, built from information already available. See how this can be done without manufacturer participation or a single committee meeting, by building a basic spreadsheet based evaluation tool to qualify products. The spreadsheet master will be made available to all who attend. ● 4. See how visual perception and accommodation to lighting conditions amplifies some problems, while erasing others, and using this to prioritize in the design process. 1

11/14/2016 Finding the happy medium between cost and result In this presentation we will… • Walk through a little background on light metering • Review affordable and practical metering approaches • Explore how meters can be used in field application • Talk about tools and accessories to improve the metering experience • Discuss common metering errors and approaches to improve results • Look at a method for classifying products based on metered results and catalog data, or both Metrics vs. Vision The human visual system has zero accuracy – cannot be calibrated to a known standard Variable, uncalibrated optical receiver parts with adaptive features that change with age Variable software with “subjective” perception feature that changes with age 2

11/14/2016 Non Linear Perception • Human perception of brightness not linear • Person to person perception is not uniform 100 100 100 97 95 95 92 90 90 89 87 85 84 81 80 80 Relative Power Level 77 75 74 70 71 70 67 65 63 60 60 59 55 55 50 50 50 45 45 40 40 39 35 32 30 30 25 22 20 20 15 10 10 5 0 0 0 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Relative Illuminance Measured Light Percieved Light Non Linear Visual Performance Response • Human response to spectral color balance is not flat • Varies by age, health, and individual preference Perceived CCT S/P Ratio EVE Factor Illuminance (20Fc Base) 2700K 0.8 1.56 12.82 3000K 1.25 1.09 18.35 3500K 1.4 1.00 20.00 4000K 1.6 0.90 22.22 5000K 2.0 0.75 26.67 Subjectivity Filter It’s too dark in here Wrong, too bright, I can still see you 3

11/14/2016 So We Invented Meters • Changes observation from subjective (looks good) to objective (numeric value) • Allows metric comparison • Between observers • Over time • Calibration = verifiable accuracy Electrophot Weston 617 1931 1932 Why Meter • Evaluate a product • Survey a lighting condition • Verify performance against a product specification • Verify performance against a calculated prediction • Monitor performance over time (color) • Track lumen depreciation • Evaluate an environment to be lighted • Solve problems or capture design data • Understand more about light in a space Testo 540 What We Meter • Illuminance • Color and color characteristics • Modulation (Flicker) • A wide range of pecific applicable characteristics • Brightness (luminance) • X-y coordinate • Duv shift • Etc… 4

11/14/2016 Data Extrapolated from Readings • Color Accuracy • CRI Ra and specific R values • TM30 Rf and Rg • MacAdam Steps from standard center point • Visual performance • Human factors • Energy vs. Power • Consistency comparison • S/P ratio • Horticultural • PPFD (Photosynthetic Photon Flux Density) • PAR (Photosynthetic Active Radiation) Factors, Approaches and Meters in Use Factoring Required for Visual Response • Need to match meter response to human visual response • Otherwise, meter is just measuring total energy collected at the photo receptor or cell, whether or not it can be “seen” 5

11/14/2016 Cosine Correction for Illuminance • Cosine correction for illuminance measurements • Does not provide luminance or spot measurement Lambert’s cosine law Accuracy vs. Precision • Accuracy is how close a meter will produce a result against a known reference or standard • Older meters are +/- 10% of any reading • Newer meters are +/- 5% Illuminance, +/-.003 in x-y, +/-3% CCT • Precision is how tight readings are to one another, sometimes referred to as repeatability • Older meters are +/- 5% • Newer meters are +/- 2% Illuminance, +/-.0015 in x-y, +/-1% CCT • Look for values that are < 50% of accuracy specification • Accuracy range: Reading vs. Full scale • Full scale is % of max reading (not good) • Reading is % of any reading (good) Analog Meters GE DW-48 1940 GE DW-58 1946 GE 214 1960 GE 217 1990 6

11/14/2016 Essentially Voltmeters and Photocells Silicon Photocell Response Volt Meter and Silicon Photocell Results 1.005 Green Filter 1.000 Relative Measurement Meter 0.995 No Filter Green Filter 0.990 0.985 CCT of Light Source 0.980 2700 3500 5000 LED Light and Analog Meters Selenium photocell not suited to measuring illuminance under LED sources If it doesn’t use a battery and an analog gage, it may have issues Low Cost Digital Meters Diffuser (Cosine Corrector) Photosensor (under diffuser) Gage (Voltmeter w/firmware) Calibration using varistor and firmware – calibrated for all light sources and daylight Amprobe LM-200LED Detachable sensor head is an excellent feature Hundreds of similar meters from $50 to $1200 7

11/14/2016 Quality Digital Meters Detachable sensor head Array of multiple sensors Minolta TM-10 Other Useful Meters Many older digital light Meters – from fluorescent era forward Check against a known modern meter to verify Minolta T-1H Minolta CM-2 Minolta AM-4F Photographers light meters -with spot attachment Meter LED Error Vs. Vs. Vs. 90 80 70 Illuminance 60 50 40 30 20 10 0 2700K 3000K 3500K 4000K 5000K DW58 10 22 32 45 60 LM-200LED 84 84 84 84 84 Minolta T-1H 83.7 84 85.1 84.1 84 GE 214 45.5 47 50 50 50 8

11/14/2016 Meter LED Error Vs. Vs. Lo Light Hi Light 100 450 90 400 80 350 Illuminance 70 Illuminance 300 60 250 50 200 40 150 30 100 20 10 50 0 0 2700 3000 3500 4000 5000 2700 3000 3500 4000 5000 K K K K K K K K K K LM-200LED Lo 74 82 83 87 90 LM-200 Hi 349 382 383 406 415 GE217 Lo 51 51.5 51.5 52 52 GE217 Hi 220 190 210 210 220 GE 214 Lo 49 48 50 50 50 GE214 Hi 240 250 240 245 240 Old School Modular Scientific Meters Tektronix Multiple detachable detectors Electronics- readout per attached head Various remote and attached sensors Calibration using firmware and varistor at gage with filters depending in attachment Modern Spectral Light Meter – App Base Diffuser (Cosine Corrector) Multiple spectral sensor Software driven gage and readout Calibration using software Assensetek Lighting Passport Detachable sensor head 9

11/14/2016 Modern Meter Delivered Results CCT 90 Parameters CRI(Ra)(R1-R8) Re(R1-15) R1~R15 CQS Illuminance Foot Candle CIE 1931 CIE 1976 Spectrum Diagram C78.377-2008 IEC-SDCM TM-30-15(Rf, Rg & Diagram) Peak Wavelength ( λ p) Dominant Wavelength ( λ D) Purity Duv SP Ratio PPFD (380~780 nm) Flicker Frequency(5-200 Hz) Flicker Percentage Flicker Index Temperature Relative Humidity Modern Meter Computer Interface CCT Desktop software evaluation tools CRI(Ra)(R1-R8) Re(R1-15) R1~R15 CQS Illuminance Foot Candle CIE 1931 CIE 1976 Spectrum Diagram C78.377-2008 IEC-SDCM TM-30-15(Rf, Rg & Diagram) Peak Wavelength ( λ p) Dominant Wavelength ( λ D) Purity Duv SP Ratio PPFD (380~780 nm) Flicker Frequency(5-200 Hz) Flicker Percentage Flicker Index Temperature Relative Humidity Integrated Meters UPRTek Metrue Sim-2 Minolta CL70 Gigahertz Optic Minolta CL500 10