1. Objectives Describe the lighting parameters Learn about lamps
Define project 2

2. Photometrics Luminous intensity [candela, cd]
Define the ability of light source to generate light (illumination) in given direction
Power – luminous flux [lumen, lm]
Quantity of light
Illuminance – light power density [foot-candela, fc]
[lux, lx] SI units
Density of light (illumination) incident on a surface
Luminance - surface brightness [foot-lambert, lm/ft2]
directional emission of visible light

3. Illuminance (E) depends on angle Example:
Spot light with luminous intensity I= 5000cd is aimed at painting at the wall 5 ft from the light and the angle φ=45°.
What is the illuminance level (E) at the center of the painting?

4. Solution Distance: Illuminance orthogonal to the beam E=I/L2=5000/
Ebeam= 100 fc
Illuminance orthogonal to the painting
Epainting= Ebeam/
Epainting=71 fc

5. Color of light
Color temperature is used to express the color of the light

6. Surface color rendering
Depending on the light type the surface colors can be different Depends on spectral energy distribution

7. Color rendering
lamp source can cause a color shift

8. Color rendering index (CRI)
Indicate if a lamp source will cause a color shift.
Definition:
CRI =100 for incandescing lamp with color temperature 3000K

9. Luminous efficacy
Define the light output per unit of electric power input
Efficacy = Lumens/Watt

10. Lifetime of lamps
Rated life of lamp is time elapsed when 50% of group of lamp remain burning.

11. Lumen deprecation Lumen output fall during the life time
Data for fluorescent lamps

12. Types: Incandescent Electric discharge Fluorescent
HID High-intensity Discharge Lamp
Ref: Tao and Janis (2001)

13. Incandescent Thomas Edison first incandescent lamp
Efficacy of 1.4 lumens/watt
Life – 750 to 1000 hours
10 – 20 % decay in output

14. Specialty Incandescent Lamps
Halogen
Low voltage
Long-life
Infrared
Interference filters

15. Is Dimming Bad For Incandescent Lamps?
- 10% lower Voltage
- 25% lower light
- life of lam doubles

16. Fluorescent Lamps Electrodes arc through mercury vapor
Phosphors fluoresce in visible range
Efficacy of 60 to 100 lumens/watt (after burn-in)

17. Ref: Tao and Janis (2001)

18. Fluorescent Lamps 20,000 hour life for tubes
Output falls off significantly (lumen deprecation)
We define mean lumens at 40% expected life
Environmental hazard because of mercury
Significant improvement with lumen deprecation and life with new types of fluorescent lamps
Start of the lamp vary with type of fluorescent lamp

19. Ballasts Why do we need ballasts? Types: Transformer –higher voltage
Limit the maximum flow of current - choke
Types:
Magnetic
Noisier, cheaper, less efficient (more heat)
Electronic
Quieter, better power factor, more expensive
Lower harmonic distortion
Higher frequency

20. Comparison Incandescent: 40 W × 8760 hr/year = 350 kWh
Demand charges, maintenance, additional cooling
Uneven illumination
LED: 1 W × 8760 hr/year = 8.8 kWh
1/40th of the energy charges, lower demand, less maintenance, lower cooling bills
More even illumination

21. High Intensity Discharge (HID)
Arc through conducting vapor
High temperature and pressure
Ceramic or quartz tubes
Glass protective casing
Also need ballast (electric discharge lamps)

22. Ref: Tao and Janis (2001)

23. Types of HID Lighting Type Color Temp. (K) Efficacy (lumens/W) CRI
Lifetime
(1000 hours)
Mercury
5710
20-60
15-50 24
HPS
High pressure sodium
2100
140
22-70
16-40
LPS
Low pressure sodium
1740
(yellow)
200 ~0
10-201
Metal Halide
3600
~100
<70
10-20
1minimal decline in output with aging

24. Issues with HID lighting
Long start-up ~ minutes
Arc needs to stabilize, heat vapor
Even longer restart
Up to 40,000 hour life time

25. What is next in lamp technology
LEDs - light emitting diodes
Semiconductor technology
Exit signs
Electrodeless Lamps
Induction lighting
Microwave lighting
High efficiency
Possible interference with
wireless networks
Nuclear Light Source

26. Comparison Type Power (W) Lifetime Incandescent 40 2 – 8 months
Fluorescent
10 – 25
1 – 2 years
LED
light emitting diodes ~1
10+ years
Tritium
nuclear
10 – 20 years

27. Lamps are not the only thing
Fixtures (luminaire)
Application requirements
Mounting
Distribution