basic lighting instructor doug avery. issues k proper illumination to perform the task k occupant...
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BASIC LIGHTING
Instructor
Doug Avery
Issues
Proper Illumination to perform the task
Occupant Comfort Energy efficiency Dispatchable and controlled
loads
Overview
Lighting Theory
Technology– Lamps and ballasts
Retrofit Options
Controls
Field Trips for practical experience
Lighting Theory
Lighting Fundamentals
Definitions• Candela: The international unit of
luminous intensity. This term has evolvedfrom the consideration of a standard candleas a basis of evaluating the intensity of otherlight sources
• Candlepower: A term used to describe
the relative intensity of a source
Definitions
Lumen: This is the international unit of
luminous flux. One lumen is the amount oflight striking a one-square-foot area, all points of which are 1 foot away from a point source of 1 candela intensity.
• Footcandle: This is the unit of measure
of the density of light striking a surface. One footcandle = 1 lumen striking 1 square foot.
1 FootcandleSquare Foot
Foot Candle
• Footlambert: This is the unit of
measure of light exiting a surface.
• Frequency : The number of complete
cycles a wave makes in one second
• Hertz: Cycles per second
More definitions
Average illuminance:This calculation predicts the average
foot-candles in a space.FC = Lm/Sq.Ft.Example: 5,000 lumens of light evenly spread over an area of 100 sq.ft.5,000 Lm/100 sq.ft. = 50 fc.
Fundamental Lighting Relationships
Inverse Square Law:This calculation is used to predict the illuminance at a specific point in space.FC = I/D2 or FC = Candlepower/distance2
If intensity is 2,000 candelas at a distance of 10 feet, the illuminance will be:
FC = 2,000 CD / 10 ft.2 = 20 fc
Another valuable formula
Light is a form of radiant energy that is capable of exciting the retina and producing a visual
sensation.
Nature of Light
The color of a light wave is determined by its length
A wave 380 Nanometers long is violetA wave 500 Nanometers long is greenA wave 580 Nanometers long is yellowA wave 620-760 Nanometers long is red
Light and Color
White light is:
A relatively balanced combination of wave lengths
Created by the blending of the primary colors of lighting: Red, Green, and Blue
Additive Property of Light:Colors added together to producewhite light
Subtractive Property of Light:Colors added together to produceblack--primary colors yellow,cyan,and magenta
Other colors created by subtracting from black.
Daylight
Cool White
White
Warm White
Candle Light
4,100
3,5003,500
3,0003,000
1,8001,800
Degrees Kelvin
Color Temperature
5,000
Measured in light output ( lumens)
per unit of power input ( watts)
Efficiency
Relative Efficacy
Incandescent 8-28 LPWFluorescent 45-105 LPWMercury 40-100 LPWMetal Halide 60-115 LPWHPS 50-140 LPWLPS 60-150 LPW
TECHNOLOGY
LAMPS
INCANDESCENT LAMPS
History
1879-Thomas Edison invented the first commercial incandescent lamp
1910-Tungsten filament introducedstill in use today
Measured in light
output ( lumens) per unit of power input ( watts)
Incandescent Lamps
– This is the ratio of total lumens to total power input.– The theoretical maximum efficacy of tungsten is 52 lumens per watt.– Efficacy increases as lamp wattage increases, however it also decreases as lamp life increases.
Efficacy
– Filled with iodine or bromine gas.– Has regenerative cycle where the
tungsten molecules go to the bulb wall--combine with the iodine or bromine, which do not adhere to the bulb wall--tungsten is redeposited on filament.
Halogen Cycle Lamps
Halogen Lamps
WHAT ARE SOME GOOD APPLICATIONS FOR INCANDESCENT
LAMPS?
THE WORK HORSE OF LIGHTING
FLUORESCENT LAMPS
History
1896: Edison applies for patent--never used1935: G.E. introduces a green lamp at IES conference.1938: First commercial fluorescent lamps
introduced.
Theory of operation:
Gaseous discharge lamps that produce light by discharging an electric arc
thougha tube filled with low-pressure gas that contains mercury atoms.
Diagram of fluorescent tube
Preheat
First fluorescent lamps were pre-heat Required a ballast and a starter to
operate Starter pre-heated cathode Very slow, usually a few seconds to start
the lamp
Instant start (Slimline) circuits
– Introduced in 1944 to overcome the slow start of the pre-heat lamps– High voltage (400 - 1000 volts) jump start
the lamp– Typically slim-line lamps since external cathode heating is not necessary
Rapid start circuits
– Introduced in 1952 to combine the advantages of both the pre-heat and instant start circuits.
– Require external heating of the cathodes, therefore use bases with two electrical contacts-- Medium bi-pin and recessed double
contact
T-8 LAMPS VS T-12 LAMPS
WHICH ONE IS THE RIGHT ONE?
F40T12 34 W CW LAMP
• 465 ma lamps operated on a 430 ma ballast• approximately 85 - 87% ballast factor 2900 initial lumens X 85% BF= 2465 lumens• approximately 37 watts (lamp and e.s.ballast)• only difference between std 40WF40 and 34W F40 is krypton gas fill• T12 diameter traps light• thermal losses
32 W T8 4100 K LAMPS
• 265 ma lamp operated with 265 ma ballast• average 91% ballast factor 2900 initial lumens X 91% BF = 2639 lumens• 11% improved efficiency due to high frequency Phosphors love high frequency• tri-phosphors permit better quality of vision
• T-8 size permits more light to exit fixture
T-5 LAMPS
Relatively new lamp Better optics, higher lumens Excellent CRI Require dedicated fixture
– High glare potential Significant energy savings
Ballasts
Ballasts limit current and provide proper voltage to the lamps they operate.
All lamps should be operated on the ballast that was designed for that specific lamp type.
Ballasts
Ballast Comparison
Electronic Magnetic
High frequency
Low heat
Adaptable for control
(dimming and day-lighting)
May cause some RFI,
(Library scanners and simplex)
Harmonics .20<
60 Hertz
High heat
Can not dim
No RFI
Harmonics .25<
Ballast Factor
This term refers to the percentage of rated lamp lumens that will be produced when the lamp is operated on a particular commercial ballastBF X rated lumens= Effective lumens
The Controversy:
Instant Start vs Rapid Start
BALLASTS
INSTANT
WHICH ONE IS BEST?
RAPID
Immediate on
Uses 1.5 watt less
Can not Dim
Can reduce lamp life
Slight delay
Need to maintain cathode heat ( +1.5 watt energy use)
Able to dim
Maintains rated lamp life at less than 3 hours per start
Fluorescent Dimming
Conventional Dimming ballasts and controls
Variable auto-transformers Electronic dimming ballasts
– Stepped dimming– Continuous dimming
Daylight Harvesting
Two strategies:– Turn off lights in
day-lighted area– Use dimming
ballasts and photoreceptors
Lumen Maintenance
Lighting systems designed for maintained levels of illumination
Achieve this level during last 1/3rd or useful life of the system
System can be tuned using electronic ballasts and a variety of controls – Exact level of light required– Energy savings
RETROFIT STRATEGIES
Incandescent to Incandescent Incandescent to Fluorescent
Fluorescent to Fluorescent
Incandescent or Fluorescent to HID
Controls
INCANDESCENT TO FLUORESCENT
FLUORESCENT TO FLUORESCENT
2x4 Troffer2x4 Troffer
o 24” o 24” k k
4 Lamp4 Lamp
3 Lamp3 Lamp
2 Lamp2 Lamp
3 3/4”3 3/4”
Fixture Comparisons
There are times when the best solution is a NEW
fixture
INCANDESCENT OR FLUORESCENT TO HID
Lighting Controls
Categories of controlsCategories of controls Simple controls On/off based
– Placement of detector is key issue– Little commissioning required– Calibration is straightforward
Advanced controls– Generally require dimming ballasts– Integration of multiple components– Allow integration of all lighting control
strategies
LIGHTING CONTROLSLIGHTING CONTROLS
Schedule lighting operation Occupancy detectors Sweep off control w/ overrides Daylight harvesting (other names
also) Lumen maintenance Load shedding
– Real time pricing Tuning
Scheduling
Predictable Unpredictable Daylighting Brightness balance Lumen Maintenance Task tuning Load Shedding
Occupancy Sensors
OCCUPANCY SENSORS are used to automatically control the lights in a space. Infrared Ultrasonic Combination of both
Occupancy Sensors
If not properly installed, calibrated and commissioned, occupancy sensors tend to disabled
Photoreceptors
Measure the amount of light in a space
On/off Send signals to
smart system for daylighting control
Dimming electronic ballasts
Stepped Dimming
Continuous dimming
Control Strategies
Employee awareness Optimal on/off sweeps Daylight harvesting Lumen Maintenance Remote control