Lighting

Lighting Systems

  1. Lamps- the light source

  2. Luminaires or Fixtures- the lamp casing or housing

  3. Controller

  • Ballasts- provide an initial spike of high voltage and then regulates the current in fluorescent lighting

  • Drivers- rectify the incoming alternating current (AC) by converting into lower voltage direct current (DC) and protects against fluctuations in LED lighting

Lamp Characteristics

  • Lumens (Light Output)

    • Measure of brightness
  • Luminous Efficacy (Lumens / Watts)

    • Light output / electrical power input
  • Colour Temperature (Kelvins)

    • Shown in the CIE chromaticity diagram
  • Colour Rendering Index (CRI)

    • Relative indicator of colours distinguished under the colour temperature, index from 0 to 1
  • Cost ($)

  • Rated Life (operating hours)

    • Time it takes for 50% of a large group to burn out. LEDs are predicted when light output decreases 30%
    • Fluorescent are rated at 3 hours per start, HID at 5 hours per start. Operating at shorter periods decreases life
  • Labour required for re-lamping (time and cost)

    • Reduced maintenance cost rather than extended lifetime is a primary factor in the payback

Lamp Types

  1. Incadescent bulbs:

The glass bulb is filled with an inert gas (ex. argon). An electric current is passed through a thin metal filament (tungsten) which acts as a resistor and is heated to produce a glow of visible light

  • Pros: renders colours well, easily dimmed and controlled, inexpensive

  • Cons: low efficacy (90% heat), short lifespan, susceptible to vibration

2. Fluorescent bulbs:

The tubes are filled with mercury vapour gas that is excited once a current is passed through it, this produces short wave ultraviolet light that stimulates the phosphor coating on the inner wall to release visible light

  • Pros: high efficacy, longer life, low surface luminance

  • Cons: trace of mercury, higher initial cost with electronic ballast

3. Light Emitting Diodes- LEDs:


The epoxy case contains the semiconductor (diodes), which are polarized to allow the flow of current from an anode (+) lead to a cathode (-) lead where electrons cross the p-n junction and emit light energy.

  • Pros: most efficient, longest lifespan, versatile and durable

  • Cons: dimmer compatibility, emit in a specific direction

CIE Chromaticity Diagram

  • All colours visible to the average human eye are mapped

  • The center is the least saturated colours and emitting from white

    • Appearance of perceived light in the colour space of a blackbody radiator at that absolute temperature scale
  • The edges are the spectral locus with the most saturated colours in pure monochromatic light

    • Measured by wavelengths, in nanometers (nm)
  • Any colour can be made by 2 others

    • It is the center of a drawn line, with the end point colours mixed

HSV Cylinder

Based on Colour Appearance Parameters: Hue, Saturation, and Value


Lighting Survey

Consider what are your:

  1. Lighting needs

    • for operating/dormant lighting to provide illumination, safety, or decoration

  2. Time and length of day that lighting is required

    • in combination with natural light, and electricity use

  3. Lighting levels for productivity and safety

    • task dedicated lighting based on the visual task, and room surface characteristics

  4. Switch control measures:

    • dimming, time, motion, infrared radiation, light-sensitive photocell

  5. Type and condition of lamps, fixtures, ballasts and the lighting installation

    • aging, depreciation, and heat production in the space

    • ambient environment; movement, moisture exposure, and temperature ranges

  6. Re-lamping practice

    • spot replacement- replacing the light once it burns out

    • group replacement- reduced cost and labour with a shorter interruption, to maintain uniform lighting and lamp use