Illumination
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The document discusses various aspects of lighting design including illumination, brightness, contrast, glare, diffusion, and color. It describes how lighting affects visual tasks and defines key lighting concepts. Specific lighting types and arrangements are also covered, such as downlighters, track lighting, and shade lighting. Proper lighting design considers factors like lighting level, uniformity, and control of glare to create a space that supports visual tasks and is comfortable for users.
Illumination
- 1. ILLUMINATION
- 2. LIGHTING LIGHTING FORM THE VERY BASIC FEATURE OF VISUAL ARCHITECTURE AND INTERIOR DESIGN.LIGHT IS A RADIANT ENERGY AND IT RADIATES EQUALLY IN ALL DIRECTIONS. OUR ABILITY TO SEE WELL,TO JUDGE SHAPE ,COLOUR AND TEXTURE ,TO DIFFERENTIATE ONE OBJECT FROM OTHER OBJECT IS AFFECTED NOT ONLY BY AMOUNT OF LIGHT AVAILABLE FOR ILLUMINATION BUT ALSO BY OTHER FEATURE LIKE BRIGHTNESS CONTRAST GLARE DIFFUSION COLOUR
- 3. BRIGHTNESS BRIGTHNESS REFERS TO HOW MUCH LIGHT ENERGY IS REFLECTED BY A SURFACE. DEGREE OF BRIGHTNESS OF AN OBJECT IN TURN DEPENDS ON THE COLOUR VALUE AND TEXTURE OF ITS SURFACE A SHINY, LIGHT-COLOURED SURFACE WILL REFLECT MORE THAN A DARK OR ROUGH TEXTURED SURFACE, EVEN THOUGH BOTH SURFACES ARE LIT WITH THE SAME AMOUNT OF ILLUMINATION TO DISCERN SHAPE ,FORM AND TEXTURE, SOME DEGREE OF CONTRAST OR BRIGHTNESS RATIO ALSO REQUIRED. EXAMPLE- A WHITE OBJECT CAN NOT BE SEEN ON WHITE BACKGROUND AS IT WOULD BE SEEN ON DARK BACKGROUND.
- 4. CONTRAST CONTRAST BETWEEN AN OBJECT AND ITS BACKGROUND IS REQUIRED FOR VISUAL TASKS THAT REQUIRE THE DISCRIMINATION OF SHAPE AND CONTOUR. MAXIMUM RATIO OF 3:1 BETWEEN THE SURFACE AND ITS BACKGROUND IS GENERALLY RECOMMENDED.HIGHER BRIGHTNESS RATIO CAN LEAD TO GLARE AND ASSOCIATED PROBLEMS .
- 5. MAXIMUM RECOMMENDED BRIGHTNESS RATIO BETWEEN 1 AND 2 IS 3:1 MAXIMUM RECOMMENDED BRIGHTNESS BETWEEN 1 AND 3 IS 5:1
- 6. GLARE ONCE OUR EYES HAVE ADJUSTED TO A CERTAIN LIGHTING LEVEL,ANY SIGNIFICANT INCREASE IN BRIGHTNESS CAN LEAD TO GLARE,EYESTRAIN AND IMPAIRMENT OF VISUAL PERFORMANCE TWO TYPES OF GLARE 1. DIRECT GLARE 2. INDIRECT GLARE DIRECT GLARE CAUSED BY BRIGHTNESS OF LIGHT SOURCE .BRIGHTER THE LIGHT SOURCE .GREATER THE GLARE INDIRECT GLARE INDIRECT GLARE IS CAUSED BY VIEWING SURFACE REFLECTING LIGHT FROM A LIGHT SOURCE INTO THE VIEWER’S EYES.
- 7. GLARE ONCE OUR EYES HAVE ADJUSTED TO A CERTAIN LIGHTING LEVEL,ANY SIGNIFICANT INCREASE IN BRIGHTNESS CAN LEAD TO GLARE,EYESTRAIN AND IMPAIRMENT OF VISUAL PERFORMANCE TWO TYPES OF GLARE 1. DIRECT GLARE 2. INDIRECT GLARE DIRECT GLARE CAUSED BY BRIGHTNESS OF LIGHT SOURCE.BRIGHTER THE LIGHT SOURCE .GREATER THE GLARE INDIRECT GLARE INDIRECT GLARE IS CAUSED BY VIEWING SURFACE REFLECTING LIGHT FROM A LIGHT SOURCE INTO THE VIEWER’S EYES.
- 8. DIFFUSE DIFFUSENESS IS A MEASURE OF LIGHT’S DIRCTION AND DISPERSION AS IT EMANATES FROM ITS SOURCE A BROAD SOURCE OF LIGHT SUCH AS LUMINOUS CEILING PRODUCES DIFFUSED ILLUMINATION THAT IS FLAT, FAIRLY UNIFORM AND GENERALLY GLARE FREE. WHITE DIFFUSED LIGHTING IS USEFUL FOR GENERAL VISION
- 9. COLOUR ANOTHER IMPORTANT QUALITY OF LIGHT IS ITS COLOUR AND HOW IT AFEECTS THE COLOURATION OF OBJECTS AND SURFACES IN ROOM. DAYLIGHT RANGE FROM PURPLE TO RED . SPECTRAL DISTRIBUTION OF ARTIFICIAL LIGHT SOURCE VARIES WITH THE TYPE OF LAMP EXAMPLE- INCANDESCENT BULB PRODUCES A YELLOW WHITE LIGHT FLUROSCENT PRODUCES BLUE WHITE LIGHT. APPARENT COLOUR OF SURFACE IS RESULT OF ITS REFLECTION OF ITS PREDOMINANT HUE AND ITS ABSORPTION OF THE OTHER COLOUR OF THE LIGHT ILLUMINATING IT.
- 10. NATURAL LIGHTING IS LIGHT AVAILABLE IN NATURE.WE PERFORM ALL OUR DAILY ACTIVITIES IN THIS DAYLIGHT. DAYLIGHT IS NOTHING BUT SUN LIGHT ON EARTH. INTENSITY OF SUNLIGHT VARIES DEPENDING ON ATMOSPHERIC CONDITION. SUNLIGHT IS BRIGHT IN MORNING ,DULL IN EVENING.ITS BRIGHTNESS MORE IN THE AFTERNOON CAUSING GLARE NATURAL LIGHTING
- 11. DAYLIGHT FACTOR THE DAYLIGHT FACTOR (DF) IS A MEASURE OF NATURAL DAYLIGHT IN A SPACE. IT QUANTIFIES THE AMOUNT OF LIGHT AT A GIVEN POINT IN A SPACE RELATIVE TO THE SIMULTANEOUS AMOUNT OF DAYLIGHT AVAILABLE OUTSIDE. A DF OF 2 PER CENT WOULD MEAN THAT THE INDOOR DAYLIGHT IS 2 PER CENT OF THE AVAILABLE OUTSIDE DAYLIGHT, I.E., IF THE OUTSIDE LIGHT IS 8,000 LX, THE INDOOR DAYLIGHT WOULD BE 160 LX. A DF OF 1 PER CENT WILL PROVIDE A LOW LEVEL OF LIGHT. A DF OF 2 PER CENT WILL BE AN "AVERAGE" DAYLIT SPACE. A DF OF 4 PER CENT WILL BE PERCEIVED AS A BRIGHT DAYLIT SPACE.“ NATURAL DAYLIGHT ILLUMINATION CAN VARY FROM 5,000 LX IN A HEAVILY OVERCAST SKY TO OVER 40,000 LX IN DIRECT SUNLIGHT. THIS IS MUCH GREATER THAN THAT NEEDED FOR ADEQUATE INDOOR LIGHTING. TYPICAL INDOOR ILLUMINATION REQUIREMENTS ARE LESS THAN 500 LX FOR WORKSPACES.
- 13. EXTERIOR SHADING • A GOOD SHADING SYSTEM WILL PERMIT LOWER LEVELS OF ARTIFICIAL ILLUMINATION TO BE SPECIFIED, BECAUSE THE EYE CAN ACCOMMODATE ITSELF WITHOUT STRAIN TO FUNCTION WITHIN A WIDE ILLUMINATION RANGE. • EXTERIOR SHADING DEVICES ARE EFFECTIVE AT CONTROLLING SOLAR GAIN. INTERIOR WINDOW SHADING WILL ALLOW MUCH • SOUTH-FACING WINDOWS ARE THE EASIEST TO SHADE. HORIZONTAL SHADING DEVICES, WHICH BLOCK SUMMER SUN AND ADMIT WINTER SUN, ARE THE MOST EFFECTIVE. • EAST- AND WEST-FACING WINDOWS ARE BEST SHADED WITH VERTICAL DEVICES, BUT THESE ARE USUALLY HARDER TO INCORPORATE INTO A BUILDING, AND LIMIT VIEWS FROM THE WINDOW.
- 14. EXTERIOR SHADING
- 15. SKY EXPOSURE • OUTSIDE OBSTRUCTIONS CAN REDUCE DAYLIGHTING POTENTIAL. • THE SKY EXPOSURE ANGLE IS THE AMOUNT OF SKY THAT CAN BE SEEN FROM A WINDOW. IT IS DEFINED AS THE VERTICAL ANGLE OF SKY BETWEEN THE TOP OF AN OBSTRUCTION AND THE VERTICAL, AND IS TYPICALLY MEASURED FROM A POINT TWO METRES ABOVE THE FLOOR. THE OBSTRUCTION
- 17. ARTIFICIAL LIGHTING ARTIFICIAL LIGHT SOURCES ARE OTHER SOURCES OF LIGHT WHICH EVELOPED TO COMPENSATE FOR OR ASSIST THE NATURAL LIGHT. IT WILL HAVE DIFFERENT FREQUENCIES AND WAVELENGTHS THAT DETERMINE THE LIGHT COLOR. ARTIFICIAL LIGHT SOURCES ARTIFICIAL LIGHT SOURCES ARE CATEGORIZED BY THE TECHNOLOGY USED TO PRODUCE THE LIGHT. THERE'S DOZENS OF SOURCES, WITH A FEW COMMON IN HOUSEHOLD APPLICATIONS AND OTHERS MORE SUITABLE FOR INDUSTRIAL USES. THE FIVE MOST COMMON LIGHT SOURCES ARE AS FOLLOWS: INCANDESCENT LAMP. COMPACT FLUORESCENT LAMP. FLUORESCENT TUBE. DISCHARGE LAMPS. LIGHT EMITTING DIODE (LED).
- 18. INCANDESCENT LAMP UNTIL RECENTLY THE MOST COMMON ELECTRIC LIGHT SOURCE WAS THE INCANDESCENT LAMP. THIS IS STILL WIDELY USED, ALTHOUGH ITS RELATIVELY LOW ENERGY EFFICIENCY IS LEADING TO ITS REPLACEMENT BY OTHER MORE EFFICIENT LAMPS SUCH AS THE CFL. A LARGE VARIETY OF SHAPES, SIZES AND POWER IS AVAILABLE, AS WELL AS DIFFERENT COLOUR RANGES. TYPICAL LAMPS FOR HOUSEHOLD USE RANGE FROM
- 19. INCANDESCENT LAMP Characteristics: Efficacy :10-20 Lumens/Watt (Typically 13 lm/W for a 100W GLS - General Lighting Service lamp) Lamp Life: 1000 hours. (This increases dramatically on reduced voltage) Colour rendering: Excellent (1A) Colour Temperature: 2700 K (Warm) Control: Fully dimmable (though a shift to red occurs). Advantages: Simple, compact, good colour rendering, cheap to install, instant light, no control gear. Disadvantage: High running cost, short life, high heat output. Applications: Domestic and short duration use in commercial and industrial installation. (e.g. cleaner’s store).
- 20. Tungsten Halogen Incandescent Lamps Characteristics Efficacy 15-25 lumens/watt (Typically 20 lm/W for a 300W linear lamp) Lamp Life: 2000 hours Colour: Rendering: Excellent (1A) Colour Temperature: 3000 K Control: Fully dimmable (Though a shift to red occurs). Advantages: Instant, cheap to install, excellent colour rendering. Disadvantages: High running cost; very hot operation; Applications for Tungsten Halogen Lamps: Security lighting, vehicle lights, short duration use e.g. T.H. are sometimes used alongside discharge lamps that require a long warm up time. The T.H. lamps only operate whilst the discharge lamps warm up. These lamps are particularly sensitive to a change in supply voltage which affects their operating temperature.
- 21. COMPACT FLUORESCENT LAMP. THE COMPACT FLUORESCENT LAMP (CFL) WAS DESIGNED AS A MORE EFFICIENT REPLACEMENT FOR INCANDESCENT LAMP. POWER RATINGS OF CFLS THAT CAN PROVIDE APPROXIMATELY THE EQUIVALENT LIGHT OUTPUT TO INCANDESCENT LAMPS.
- 22. FLUORESCENT TUBE FLUORESCENT TUBES ARE THE MAIN FORM OF LIGHTING FOR OFFICES AND COMMERCIAL BUILDINGS. THEY ARE A FORM OF GAS DISCHARGE LAMP, AND ARE FORMED IN A LONG THIN GLASS CYLINDER WITH CONTACTS AT EITHER END THAT SECURE THEM TO THE FITTING (OR LUMINAIRE) AND PROVIDE THE ELECTRICAL CONNECTION.
- 23. DISCHARGE LAMPS DISCHARGE LAMPS WORK BY STRIKING AN ELECTRICAL ARC BETWEEN TWO ELECTRODES, CAUSING A FILLER GAS TO GIVE OFF LIGHT. DIFFERENT METALS AND FILLER GASSES CAN BE USED TO PROVIDE A RANGE OF COLOUR AND BRIGHTNESS.
- 24. LIGHT EMITTING DIODE (LED) LEDS USE SEMI-CONDUCTORS TO CONVERT ELECTRICAL ENERGY DIRECTLY INTO LIGHT. THEY ARE ONLY RECENTLY BECOMING AVAILABLE AS A LIGHT SOURCE FOR LIGHTING PURPOSES, AND ARE HIGHLY EFFICIENT AND LONG LASTING. LED TORCHES ARE BECOMING VERY POPULAR, AS THEY PROVIDE A FAR LONGER BATTERY LIFE THAN OTHER TYPES OF LIGHT SOURCE.
- 25. DIFFERENT TYPE OF LIGHTING ARRANGEMENT • DIRECT LIGHTING Angular fitting Down lighter Eyeball Track lighting Shade lighting • INDIRECT LIGHTING • DIFFUSED LIGHTING • COMPOSITE LIGHTING • CONCEALED LIGHTING
- 26. ANGULAR FITTING IN THIS TYPE OF ARRANGEMENT ,THE LIGHT CAN BE TURNED AND POINTED IN ANY DIRECTION.IT IS A COMFORTABLE TYPE OF LIGHTING BECAUSE THE LIGHT IS ACTUALLY DIRECTED TOWARDS THE ACTIVITY LIKE READING OR WRITING.
- 27. DOWN LIGHTER SOURCE OF LIGHT IS CONCEALED IN THE CEILING.EVEN THOUGH SOURCE OF LIGHT NOT SEEN ,LIGHT IS PROJECTED DOWNWARDS WHEREVER IT IS NEEDED TO PERFORM AN ACTIVITY.DOWN LIGHTER USEFUL FOR READING AND OTHER ACTIVITY PERFORMED AT AT A FIXED PLACE IN ROOM.
- 28. EYEBALL FITTING SIMILAR TO DOWN LIGHTER BUT IT IS POSSIBLE TO DIRECT THE LIGHT IN ANY DIRECTION. IT CAN LIGHT UP DARK AREAS OF A ROOM AS IT CAN BE DIRECTED IN ANY DIRECTION. IT HAS GREATER FLEXIBILITY AND OCCUPIES LESS SPACE
- 29. TRACK LIGHTING TRACK LIGHT IS VERY POPULAR.IT IS VERY EFFECTIVE AND DRAMATIC. A SIMPLE TRACK IS WIRED AND FITTED ON THE WALL OR THE CEILING ACCORDING TO THE NEED OF THE USER. SPOTLIGHT CAN BE USED TO ILLUMINATE A PAINTING OR TO GET A SPECIAL EFFECT.
- 30. SHADE LIGHTING SIMPLE AND ORDINARY LIGHTING FOUND IN OUR HOUSE.IT CAN BE FIXED TO A WALL OR HANGED AT LOW LEVEL LEVEL OVER A TABLE.THE LIGHT SOURCE IS COVERED BY A SHADE.IT IS FIXED AND CAN NOT BE MOVED OR DIRECTED TOWARDS ANY PLACE.SOMETIMES IT IS POSSIBLE TO RAISE OR LOWER THE SHADE.