Introduction in Lighting Design Process

You can review the following previous topics for more information and good following. 

Most buildings have some type of day lighting. The majority of commercial, industrial and institutional buildings have windows and in some cases skylights and more extensive day lighting systems.

In planning lighting design for any space, the first step that a lighting designer should always first consider the potential of that space to take advantage of the many benefits of day lighting. The day lighting opportunities can best be considered as standard, advanced and integrated based on the following scenarios:

A- Standard:

The architecture, building orientation, fenestration, windows and day lighting opportunities will be fixed when the lighting design process start.

Evaluation for standard scenario:
  • Can daylight provide any useful illumination during occupied hours? 
  • If so, can some electric lighting be dimmed or turned off in response? 
  • If so, can the electric lighting be circuited to facilitate either manual or automatic control of the lights? 

B- Advanced :

The lighting designer has the opportunity to influence some of the building’s glazing properties, shade controls and other features to improve the daylighting potential.

Evaluation of advance scenario:
  • For windows, recommended external shading devices or internal window controls such as blinds to allow occupants local adjustments to avoid discomfort. 
  • For skylights or roof monitor, recommended the use of diffusing glazing materials and/or baffles or louvers to diffuse the sunlight. 
  • Work with the design team to evaluate the impact of changes in glazing performance on occupant discomfort. 
  • Can the occupant’s activities be re-positioned so that they will not be bothered by the potential glare sources? 
  • Work with the design team to evaluate the potential glare sources through the windows or skylights, such as white or bright reflective surfaces that may reflect sunlight into the space. 

C- Integrated:

An in depth analysis can be performed to maximize day lighting potential with full integration architectural elements with electric lighting and controls, to provide high quality daylighting illumination.

Evaluation of integrated scenario:
  • Evaluate if there are ways that the quality, distribution or amount of the daylighting can be improved during pr-design and schematic design phases. 
  • Utilize modeling software to evaluate full integration of daylighting, electrical lighting, control and building characteristics such as: 
  • Placing windows closer to ceiling or wall services to get better distribution. 
  • Raising the ceiling plane to allow higher windows. 
  • Increasing the visible light transmission of the windows to allow more daylight into the space. 
  • Positioning reflective surfaces, either internally or externally to direct more daylight deeper into the space. 
  • Increasing the reflectance of important interior surfaces that will help distribute the daylight deeper into the space. 

2- Factors that can be controlled in the design of a lighting system 

The second step in producing the right lighting design is to ask what the space is used for. The lighting designer can then determine direction of light, color quality, quantity and illuminance.

From the above previous topics , you can know the suitable luminaires types for each space function and you can also determine the best arrangement of it if you know how to control and enhance your designed lighting systems by controlling the following factors:

  • Direction.
  • Color.
  • Quantity (illuminance).

A- Direction:

Directionality of the lighting can enhance and emphasize an object’s perceived shape or form.

Techniques used in controlling Directionality

  1. Key.
  2. Fill.
  3. Grazing.
  4. Wall washing.
  5. Silhouette.
  6. Uplight.

1- Key Light: (see fig.1)

fig (1)

Single point source of light Provides highlights and casts shadows providing contrast and producing definite focus.

2- Fill Lighting: 
(see fig.1)

  • Multi-directional or diffuse light Reduces shadows on an object caused by the key light.
  • If totally diffuse, creates a cloudy day feeling and minimizes shadows, which may be desirable for certain tasks.

3- Grazing:

  • Occurs when light strikes a surface at a sharp angle, nearly parallel to a rough surface.
  • Enhances any variations in surface depth, revealing texture.
  • Will also emphasize flaws and unevenness in surfaces.

4- Wall Washing:

  • Occurs when light strikes a surface at a wide angle.
  • Provides even lighting on a vertical space, increase luminances of wall surfaces, and extend the space. 

5- Silhoutte:

  • Light source is used not to illuminate an object itself, but its background.
  • Applicable when one aims to reveal the outline of an object against a brighter surface and to create separation between the object and its background.

6- Uplight:

  • Places a light source below an object.
  • Produces shadows that are reversed from how an object is shadowed in daylight.
  • Creates an eerie, unnatural effect because it replaces the more familiar overhead orientation of the light source. 

Ideal Direction of the Lighting
  • Should be determined by the space function or tasks.
  • Shadows at a work task may be irritating.
  • Excessive concentration and constant re-adaptation of the eye can cause visual fatigue and a loss in performance or increase in accidents.
  • Highlights and shadows must be used sparingly depending on the task to prevent the introduction of negative factors.
  • Highlights and shadows, on the other hand, provides a pleasant visual environment located away from the major tasks.

B- Color:

Color is defined with a variety of metrics but the 2 most common are:

  1. Correlated Color Temperature (CCT).
  2. Color Rendering Index (CRI).

1- Correlated Color Temperature (CCT):

  • Represents the relative whiteness of a light source, whether the source appears warm, cool or neutral.
  • Measured in Kelvin (°K).
  • Acceptable range of CCTs for indoor environments is between 2500°K and 5000°K, with the higher value representing a cooler source.
  • Often the first criterion considered in the development of a space’s image.
  • CCT of a lamp refers to the absolute temperature of a blackbody when its visible radiation most closely matches the color of the lamp. 
  • Major mood-setting element of the space.
  • Warm color helps to create an intimate or cozy space.
  • Cool color associated with a business like environment.

2- Color Rendering Index (CRI):

  • CRI rating indicates how well an object’s colors are rendered by a source. 
  • It is a comparison of 8 specific test colors under an ideal light source in question. 
  • When color rendering is important, a source with a high CRI (e.g. 3500°K fluorescent with a CRI of 85) should be selected.
  • If not important, a CRI in the mid 70s is less expensive and may meet the client’s needs.
  • If extremely important, a CRI in the 90s may be recommended.

C- Quantity (Illuminance):

  • Quantity of light is commonly described in illuminance levels because these are easy to measure.
  • Light Level or Illuminance, is the total luminous flux incident on a work plane, per unit area. The work plane is where the most important tasks in the room or space are performed. 
  • There are recommended minimum illuminance for each place or job task that must be verified to have an acceptable lighting intensity and good lighting distribution in each place. 

Direct Glare

  • Direct glare is caused by excessive light entering the eye from a bright light source. 
  • Direct glare can be minimized with careful equipment selection and placement. In interior applications, indirectly light the walls and ceiling A limited amount of direct light can provide accent and task lighting. In exterior applications, use fully shielded luminaires that directs light downwards towards the ground or a building fa├žade. 

Please remember that A good lighting design should
  • Look good. 
  • Provide the proper amount of light in every room. 
  • Be built and constructed within budget, code, and other constraints. 
  • Be environmentally responsible. 
  • Respond to the Architecture and Interior Design. 
  • Produce good color. 
  • Achieve the desired moods of each space. 
  • Be able to control the lights. 

in the next topic, I will explain General Power (general Purposes) Loads types and classifications. so, please keep following.

Note: these topics about lighting in this course EE-1: Beginner's electrical design course is an introduction only for beginners to know general basic information about electrical lighting loads. but in other levels of our electrical design courses, we will show and explain in detail the lighting design calculations with examples for different types of buildings.

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