CHAPTER 4

• Table of Contents


  • 4.1 A Chronicle of Artificial Lighting
  • 4.2 Elements of Seeing
  • 4.3 Light
  • 4.4 The Color of Light
  • 4.5 Characteristics of Artificial Lighting
  • 4.6 Types of Artificial Light Sources
  • 4.7 Forms of Architectural Lighting
  • 4.8 Lighting Installations
  • 4.9 Light Distribution and Glare
  • 4.10 Illuminance and Luminance
  • 4.11 Principles of Lighting Design
  • 4.12 Lighting Design Practices and Considerations
  • 4.13 Lighting System Controls
  • 4.14 Daylighting Principles
• Lighting accounts for 20 to 25% of the electricity consumed in the United States and Canada and almost 20% of total global electricity consumption
• Fundamental reasons for providing light in a space

  To make the objects in the space visible and to conduct activities that must take place in the space
• Good architectural lighting provides the right quantity of light, with excellent color rendition and minimal glare. Quality lighting has been shown to improve productivity and enhance worker satisfaction
• This chapter introduces basic lighting terminology and the procedures of simple lighting design. This presentation highlights material that acquaints the technician with basic design principles
• A Chronicle of Artificial Lighting

  1. Light has played an important role in human activity throughout history

  2. Up until the early part of the 20th century, people have relied on natural lighting and flame sources such as wood, candle wax, whale oil, coal oil, coal gas and kerosene

  3. With the advent of electricity and incandescent lamps, communities started switching to the safer, cost-effective electricity powered lighting
• Foot-candle


  The earliest known unit of illumination still used today
• Herman Sprengel


  A German chemist who invented a more efficient vacuum pump in 1865 which was critical to the development of incandescent light bulb
• Joseph Swan


  First developed a working incandescent light bulb using carbon-filament lamp in February 5, 1879
• Thomas Alva Edison


  • First announced the successful development of an incandescent lamp with a baked carbonized cotton thread filament in December 21, 1879
  • First to develop a commercially feasible electric light, a low-cost lamp that could remain lit for a long period of time
• Edison Electric Light Company later known as Consolidated Edison Company powered incandescent streetlights and lamps in parts of London and later in New York which served as a model for future utilities


  1882
• The Niagara Falls Power Company became the first commercial utility to produce and transmit hydroelectric power


  August 26, 1895
• General Electric introduced fluorescent lighting, an electric light source that is more efficient than the incandescent lamp


  1939
• Professional organizations related to building lighting and electrical systems

  • Illuminating Engineering Society of North America (IESNA)
  • International Association of Lighting Designers (LALD)
  • National Electrical Manufacturers Association (NEMA)
  • American Lighting Association (ALA)
• National Electrical Code (NEC)


  • Model code that specifies the minimum provisions necessary for protecting people and property from the use of electricity and electrical equipment
  • Applies to both the manufacture and installation of electrical equipment
  • Most municipalities and counties require that residential and commercial electrical wiring conform to the NEC
  • In some jurisdictions, certain NEC requirements are superseded by local requirements
  • Lighting installations powered by electricity must comply with this code
• ASHRAE/IESNA 90.1


  • Addresses energy consumption in commercial and high-rise residential buildings
  • Sets minimum performance standards for building systems and components that have an impact on building energy consumption, including the building envelope, heating, ventilation and air-conditioning (HVAC) systems, and lighting
• Elements of Seeing


  Design of a good lighting system involves application of a blend between scientific principles, artistic skill, and design experience
• Optics


  • Branch of physics that relates to the properties of light and the function of vision
  • Involves a study of the human visual system and how it interacts with light
• Visual system


  Composed of the eye, optic nerve, and certain parts of the brain
• Eye


  Organ that allows a human to sense light and produce electrical impulses that will be sent through the optic nerve to the brain
• Brain


  Part of the visual system where the impulses are processed
• The eye functions much like a simple, very crude camera
• Iris


  • Surrounds the pupil and adjusts for the amount of light available
  • Opens and closes to control the quantity of light the interior of the eye receives, much like the aperture on a camera opens and closes to limit the light to which the film is exposed
• Lens


  • Transparent ellipsoidal medium that changes thickness, allowing it to bend and focus the rays of light entering the interior of the eye
  • Thickens to focus rays of light from objects nearby and narrows to focus light from distant objects
  • Concentrates the rays of light on the retina
• Retina


  • Composed of nerve cells with photoreceptors that are shaped like rods and cones
  • Photoreceptors do not discern color well, so dimly lit objects are perceived as being uncolored-that is, seen in shades of gray
  • Photoreceptors that are shaped like cones provide color vision and respond best to bright light
• Cone-shaped photoreceptors


  • Three different types in the retina, each responding to one of the primary colors of light: red, green, and blue
  • In individuals with normal vision, the electrical impulses from each cone blend together to create the sensation of other colors
• Color blindness


  • Inability to distinguish colors
  • Most common form is found in those individuals who have difficulty distinguishing red from green
  • Individuals who are completely red-green color-blind see yellows and blues normally, but have trouble differentiating reds and greens
  • Individuals who are totally color-blind see only black, white, and shades of gray
• Light


  • Form of energy known as electromagnetic radiation
  • Travels as an electromagnetic wave
  • Travels through the vacuum of space - unlike sound
  • Travels at 300 000 km/s
• Electromagnetic radiation


  • Energy radiated in the form of a wave caused by an electric field interacting with a magnetic field
  • Result of the acceleration of charged particles
  • Categorized by wavelength and frequency
• Wavelength


  • Measured as the distance from one peak of one wave to the next wave
  • Expressed in meters or nanometers (1 nm = 0.000 000 001 meter or one billionth of a meter)
• Frequency


  • Number of wave cycles per second
  • Expressed in units of hertz (Hz)
• Most light sources emit electromagnetic radiation composed of different wavelengths of light
• Sunlight striking the earth's outer atmosphere is made up of ultraviolet (about 5%), visible light (about 45%), and infrared (about 50%) radiation
• Classifications of electromagnetic radiation spectrum

  • Cosmic rays
  • Gamma rays
  • X-rays
  • Ultraviolet
  • Visible light
  • Infrared
  • Microwaves
  • TV waves
  • Radio waves
• Visible light spectrum by color

  • Violet (380-450 nm)
  • Blue (450-495 nm)
  • Green (495-570 nm)
  • Yellow (570-590 nm)
  • Orange (590-620 nm)
  • Red (620-750 nm)
• Visible light


  • Part of the electromagnetic radiation spectrum that is capable of exciting the retina and ultimately producing a visual sensation
  • The wavelengths of electromagnetic radiation to which the human eye is sensitive
• Illuminance


  The amount of light incident on (striking) a surface
• Luminance


  • How bright an object appears
  • The eye sees luminance as the light leaving an object, but the eye cannot see it without visible light reflecting off the object in the direction of the viewer
• Reflectance


  • The ratio of reflected light versus the light striking the surface
  • Specular reflection occurs when light is reflected off a polished or mirror-like surface
• Transmittance


  • The ratio of light transmitted through a body to the light illuminating the surface
  • A transparent body transmits light without distorting the image
  • Frosted glass is a type of translucent medium
  • Ordinary window glass is an example of a transparent medium