Test 1 Flashcards
(23 cards)
WHAT IS THE DEFINITION OF LIGHT?
- IT MAKES THINGS VISIBLE
- IT IS ELECTROMAGNETIC RADIATION TRANSMITTED THROUGH SPACE
- IT’S THE PART OF THE ELECTROMAGNETIC SPECTRUM VISIBLE TO THE HUMAN EYE
WHAT IS A LOW COLOUR TEMPERATURE LIGHT?
BELOW 3000K, RED/YELLOW COLOUR, WARM
WHAT IS A HIGH COLOUR TEMPERATURE?
ABOVE 4000K, BLUE COLOUR, COOL
WHAT IS EFFICACY?
THE RATIO OF THE LIGHT OUTPUT (LUMENS) TO THE ENERGY INPUT (WATTS), MEASURED IN LUMENS/WATT
WHAT ARE SOME LAMP TYPES?
- INCANDESCENT
- HALOGEN
- FLUORESCENT
- LED
- PLASMA
- INDUCTION
WHAT ARE THE COMPONENTS OF A LUMINAIRE?
- LAMP
- BALLAST
- DRIVER
- HOUSING
- INTERNAL WIRING AND SOCKETS
- OPTICS
- MOUNTING HARDWARE
LUMINOUS INTENSITY
-IT TELLS YOU HOW BRIGHT THE LIGHT SOURCE IS
-EXPRESSED IN CANDLEPOWER (IMP) OR CANDELA (METRIC)
-CONSIDERED A POINT SOURCE
-WHEN LIGHT IS EMITTED NON-UNIFORMLY YOU GET A CANDLEPOWER DISTRIBUTION CURVE
FORMULA IS I=E*DISTANCE^2
LUMINOUS FLUX
- REPRESENTS THE LIGHT POWER RADIATING FROM A LIGHT SOURCE
- IN LUMENS
- 1 LUMEN IS THE AMOUNT OF LIGHT POWER RADIATING FROM A POINT SOURCE OF 1 CANDLE TO 1FT OR 1 M^2 OF A SPHERE OF RADIUS 1 FT OR 1M RESPECTIVELY
INVERSE SQUARE LAW
- A SPHERICAL SURFACE AREA OF 1 FT2 AT A DISTANCE 1 FT FROM A CANDLEPOWER SOURCE RECEIVES 1 LUMEN OR 1 FOOT CANDLE OF ILLUMINATION
- IF THE DISTANCE BECAME 2 FT FROM THE SOURCE THEN THE SURFACE AREA WOULD BECOME 4 FT2 AND THEN THE 1 LUMEN ID SPREAD ACROSS 4 FT2, THE ILLUMINATION IS 1/4 FOOTCANDLES
TRANSMITTANCE AND EXITANCE
- IS THE AMOUNT OF FLUX (TRANSMITTED) PASSED THROUGH A TRANSLUCENT MATERIAL COMPARED TO THE FLUX ENTERING THE MATERIAL
- NO UNITS (SOMETIME EXPRESSED AS %)
REFLECTANCE
-THE AMOUNT OF LUMINOUS FLUX (REFLECTING) LEAVING A SURFACE COMPARED TO THE LUMINOUS ARRIVING AT THE SURFACE
TYPES OF REFLECTANCE
- SPECULAR - ANGLE OF INCIDENCE = ANGLE OF REFLECTANCE -> MIRROR OR GLOSSY SURFACE
- DIFFUSE - FLUX IS SCATTERED EQUALLY AT ALL ANGLES AND THE FLUX DENSITY IS DEPENDANT ON THE ANGLE OF INCIDENCE -> DULL, MATTE, OR ROUGH SURFACE
- SPREAD - COMBO OF 1+2 -> GLOSSY SURFACE
GLARE
- HARD TO MEASURE + IS SUBJECTIVE DEPENDING ON VIEWER
- DISABILITY GLARE -> PREVENTS (OBSCURES) ADEQUATE VISION
- DISCOMFORT GLARE -> DISCOMFORTING, BUT NOT OBSCURING VISION
- NUISANCE GLARE -> BOTHERSOME, BUT NO DISCOMFORT OR OBSCURING
- SPILL IS A TYPE OF NUISANCE LIGHTING TRESPASSES BEYOND TARGET AREA
- BARE LAMPS ARE A MAJOR SOURCE OF GLARE
- HIGH BRIGHTNESS NEXT TO LOW BRIGHTNESS CAUSES GLARE
- AVOID CONTRASTS GREATER THAN 10:1 TO CONTROL GLARE
CONTRAST
- CONTRAST IS THE COMPARISON OF TASK LIGHT + BACKGROUND
- AVOID CONTRASTS GREATER THAN 10:1 (BLACK/WHITE)
- EYES ARE DRAWN TO AREAS OF BRIGHTNESS
- AN AREA ON THE 2X AS BRIGHT AS SURROUNDING AREA HAS A 2:1 RATIO
- 5:1 -> DISTINCT FOCAL POINT
- 15:1 -> DRAMATIC FOCAL AREA
LIGHTING FIXTURE TYPES
- RECESSED COVE
- INDIRECT PENDANT
- DIRECT/INDIRECT PENDANT
- RECESSED CAN
- WALL WASHED
- WALL SCONCE
- TASK LIGHTING
- UNDER CABINET
WHAT IS THE COEFFICIENT OF UTILIZATION?
- RATIO OF LUMENS ON THE WORK SURFACE TO THE LUMENS EMITTED BY THE LUMINAIRE
- MEASURE OF THE EFFICIENCY OF A LUMINAIRE IN TRANSFERRING FLUX TO THE WORKING PLANE IN A PARTICULAR AREA
- INFLUENCED BY THE REFLECTANCE VALUES OF MATERIALS, SIZES, + SHAPE OF THE ROOM AND THE PLACEMENT OF THE LUMINAIRE
- HIGH CU MEANS MORE LIGHT
SPACING CRITERIA
-THE MAX ACCEPTABLE DISTANCE BETWEEN FIXTURES WHEN LAID OUT IN A ROOM
COMPUTER AIDED DESIGN
- USED TO SIMPLIFY DESIGN
- TO SIMULATE YOU NEED: TYPE OF LIGHT + LUMEN OUTPUT, REFLECTANCE VALUES FOR WALLS/FLOORS/CEILINGS, DESIRED ILLUMINATION LEVEL IN SPACE
LIGHTING EXPRESSIONS
- ARRANGEMENT OR ORGANIZATION OF A LIGHTING SYSTEM’S LAYOUT WILL BE A FACTOR IN AN OCCUPANT’S PERCEPTION OF A SPACE, SOMEWHAT SUBJECTIVE
- NEUTRAL
- EXPRESSIVE
- DOMINANT
- CONFUSED
CANDLEPOWER DISTRIBUTION CURVES
- PROVIDES INFO ON HOW LIGHT IS EMITTED FROM A LAMP OR LIGHT FIXTURE
- DESCRIBES THE DIRECTION + INTENSITY OF LIGHT FROM THE LUMINAIRE
- MEASURE OF LIGHT OUTPUT FROM THE SOURCE
- CAN HELP DETERMINE IF THE FIXTURE MAY CREATE PROBLEMS WITH GLARE AND HOT SPOTS
LIGHTING CONTROLS
- POPULAR TO TAKE BETTER CARE OF ENERGY USAGE
- REQUIRE ADDITIONAL CAPITAL COST + ONGOING MAINTENANCE, PAYS BACK IN ENERGY COST SAVINGS OVER BUILDING LIFE (PAYBACK)
- ASHRAE REQUIRES:
- 20 MINS AUTO TURN OFF IN UNOCCUPIED AREAS
- HALF OF RECEPTACLES NEED TO AUTO SHUT OFF WHEN UNOCCUPIED FOR >20 MINS
- AUTO DAYLIGHTING CONTROL FOR PRIMARY AND SECONDARY AREAS CONTROLLED SEPARATELY
- AUTO PARTIAL OFF SPACES
- ANALOG LIGHTING CONTROLS-> USE VOLTAGE TO CONTROL THE LIGHT OUTPUT OF A FIXTURE
DAYLIGHTING
- DAYLIGHT IS MEASURED BY THE DAYLIGHT FACTORY METHOD
- DESCRIBE RATIO OF OUTDOOR ILLUMINANCE OVER INDOOR ILLUMINANCE, IN %
- INDOOR ILLUMINATION HAS 3 COMPONENTS: SKY COMPONENT, EXTERNALLY REFLECTED COMPONENT, INTERNALLY REFLECTED COMPONENT
- ACCEPTABLE RANGES: 1.5% = ORDINARY SIGHT, <2% = ROOMS LOOK GLOOMY, 2-5% = PREDOMINATELY DAYLIT, >5% = STRONGLY DAYLIT
SITE LIGHTING
- BASED ON MUNICIPALITY GUIDELINES/BYLAWS
- 3 IMPORTANT ITEMS: PROVIDE MIN. LIGHT LEVELS, ELIMINATE LIGHT POLLUTION, LIMIT LIGHT TRESPASS
