Why Lighting? Lecture 14. Why Lighting? Lighting Terminology Vision Visual Comfort Lighting Design. Why Lighting?

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1 Environmental Controls Lecture 14 Why Lighting? Lighting Terminology Vision Visual Comfort Lighting Design Why Lighting? Why Lighting? Work/Efficiency Mood/Sense of Place/Excitement Directionality/Progression Emphasis on Form/Texture Color/Art/Whimsy Energy Efficiency/Connection to Nature 1

2 Work/Efficiency Gund Hall, John Andrews, 1972 O Hare Baggage Facility, C. F. Murphy & Associates Mood/Sense of Place/Excitement California Aerospace Museum, Frank Gehry, 1984 Mood/Sense of Place/Excitement St. Mary s Church, Ryan, McSweeney and Lee,

3 Mood/Sense of Place/Excitement U. S. Pavilion Expo 67, Buckminster Fuller, 1967 Mood/Sense of Place/Excitement San Juan Capistrano Library, Michael Graves, 1982 St. John s Abbey Church, Marcel Breuer, 1965 Directionality Progression Houston International Airport, Goleman, Rolfe, Pierce & Pierce, 1969 Banco de Credito del Peru, Arquitectonica,

4 Directionality Progression Brooklyn Children s Museum, Hardy, Holzman and Pfeiffer Associates, 1979 Collegio Teriesano, Antonio Gaudi, Emphasis on Form/Texture Banco de Credito del Peru, Arquitectonica, 1988 St. Louis Art Museum, Hardy, Holzman, and Pfeiffer Associates, 1977 Emphasis on Form/Texture Law Court at Robeson Square, Arthur Erickson Sawgrass Mills, Arquitectonica,

5 Color/Art/Whimsy San Juan Capistrano Library, Michael Graves, 1982 Walner House (Pool House), Arquitectonica, 1987 Color/Art/Whimsy Des Moines Art Center, Richard Meier, 1985 Color/Art/Whimsy Scarborough College, John Andrews, 1965 Japan Pavilion Expo 92, Tadao Ando,

6 Energy Efficiency/Connection to Nature Walner House, Arquitectonica, 1987 Energy Efficiency/ Connection to Nature Aid Association For Lutherans, Desmond & Lord Warnock & Associates Energy Efficiency/Connection to Nature Paimio Sanitorium, Alvar Aalto,

7 Energy Efficiency/Connection to Nature Technical University Helsinki, Alvar Aalto, 1964 Terminology Professional Societies IESNA: Illumination Engineering Society of North America IALD: International Association of Lighting Designers 7

8 Light Visually evaluated radiant energy Color is determined by wavelength violet is shortest, red is longest Color Classification Systems Ostwald Munsell Color Temperature Based on degrees kelvin 8

9 Chromaticity Tristimulus Factors: x, y, z Combining Light White Light: equal amounts of each wavelength Light: additive Pigments: subtractive Transmittance Factor Ratio of total light transmitted through material to the total incident light T=Transmitted/Incident 9

10 Reflectance Factor Ratio of total light reflected from a material to the total incident light R=Reflected/Incident Perfect Reflector: Silvered Mirror Perfect Absorber: Matte Black Finish Angle of Incidence & Surface Characteristics Angle of Incidence = Angle of Reflection S: F11.3 p. 470 Luminous Intensity (I) Force that generates the light we see (candlepower) S: F11.5 p

11 Luminous Flux Photometric measurement of light (lumens) S: F11.5 p.471 Illuminance(E) Luminous flux per a unit area 1 Lumen/Ft 2 1 Foot-candle 1 lumen/m 2 1 Lux Note 1 FC = Lux S: F11.5 p.471 Efficacy Efficiency of lighting system Sun: 100 lumens/watt Sky: 125 lumens/watt Incandescent: lumens/watt Fluorescent: lumens/watt 11

12 Spectral Energy Distribution Curve (SED) Graphic representation of light energy distribution of a light source Vision Vision Daylight vision controlled by cone cells: color and detail Nighttime vision controlled by rod cells: motion S: F11.18a p

13 Photopic vs. Scotopic Daytime vision: Photopic Nighttime vision: Scotopic Human Factors Sensitivities affect what light is actually seen Other Factors: Age Health Gender S: F.11.6 p. 472 Visual Comfort 13

14 Quality of Light Direct Glare Veiling Reflections Subjective Brightness Direct Glare Distracting/brightness reduced Eye is drawn to and from source Continuous adaptation S: F11.23 p.499 Veiling Reflections Indirect glare Contrast is reduced Physical movement Continuous adaptation S: F11.23p

15 Subjective Brightness Caused by a bright surface overwhelming an adjacent darker surface Eye adapts to the brighter surface Darker surface appears darker than it is. Soft frame Controlling Glare Physical arrangement Adjust brightness Select light source to minimize glare Change task quality Luminance Ratios 1 to 1/3 Task Adjacent surroundings 1 to 1/10 Task Remote dark surface 1 to 10 Task Remote bright surface 20 to 1 Luminaries/windows adjacent surfaces 40 to 1 Anywhere in field of view 15

16 Visual Attention 3 to 1 Luminance ratio will be noticeable 10 to 1 Luminance ratio will hold attention 50 to 1 luminance ratio will command exclusive attention Visual Acuity Task Lighting Conditions Observer Task Primary Factors Size Brightness Contrast Exposure time Secondary Factors Type of object Degree of accuracy Motion Peripheral patterns 16

17 Lighting Conditions Primary Factors Illumination level Disability glare Discomfort glare Secondary Factors Luminous ratios Brightness patterns Chromaticity Observer Primary Factors Condition of eyes Adaptation level Fatigue level Secondary Factors Psychological reactions Lighting Design 17

18 Quantitative Factors Daylight integration with electric light Energy relationships Space arrangements Physical characteristics of light Visual needs Pattern factors Qualitative Factors Relationships between light and shadow Use of color Artistic effects Relationships Between Light and Shadow Lighter colors advance Darker colors recede 18

19 Light sources and materials can alter perception of color Use of Color Metameric shift Tungsten Daylight Fluorescent Combine materials and light sources Artistic Effects O Hare Connector 19