Types Of Control

Artificial lighting is needed when the nautral light in a space diminshes below the level required for the task. As the daylight diminishes, the artificial lighting should increase and compliment the natural lighting and maintain the illumination required. During the hours of complete darkness, the artificial light should take over providing the task are illumination. In the majority of areas, local control provides the best solution because:

  • End users prefer to have control of their own areas. If the users have local control, they often will tolerate a larger range of environmental conditions.
  • Occupants of the spaces can have more choice over their surroundings making them feel more comfortable.

Lighting controls should be implemented carefully and thought should be given to who will be operating the system. The lighting controls should:

  • Should not add any delays in responding to commands
  • Be easy to use for non technical people
  • Ensure the user knows the controls are working by giving feedback
  • Be easy to change if the building or layout of the space changes
  • Be initially commissioned correctly and maintained properly

The choice of lighting control should reflect the usage, activity performed, occupancy and the available daylight in the area. Ideally the overall area should be split down in to zones as shown in the following diagram.

Control Zones
  • Owned space: small rooms with one or two occupants, for instance a cellular office
  • Shared space: areas with multiple occupants, for instance an open plan office
  • Temporarily owned space: areas where the occupants expect to be able to control the lighting, for instance an interview or meeting room
  • Occasionally occupied space: areas where the users do not continually occupy, for instance, storerooms or toilets
  • Unowned spaces: areas where users expect the lighting to function but do not expect to operate the lighting, for instance, corridors
  • Managed spaces: areas where someone is in charge of the controls but occupants do not operate the controls, for instance, Atria, concourses, entrance halls, libraries and shops.

The tables shown can be adapted to suit the majority of applications other than office workspaces, for example education establishment. For some applications it may be needed to add functionality, in temporarily owned areas, dimming override may be required.

The tables shown show the type of lighting control which should be considered to be appropriate to each space with respect to occupancy and daylight contribution. Areas with a daylight factor of less than 0.5% have little or no daylight. Areas with a daylight factor of greater than 2% are suitable for photocell control unless the designed illumination levels are low.

Daylit High Occupancy

  • At A Glance
  • Selection Filter

At A Glance

Control
Owned
Shared
Temporarily Owned
Unowned
Managed
Presence Detection
Absence Detection
Photocell Control
Daylight Dimming
Manual Switching
Flexible Switching
Dimming Override
Timeclock Control
Centrally Managed

Selection Filter

Reset Filters
  • Presence Detection
  • Absence Detection
  • Photocell Control
  • Daylight Dimming
  • Manual Switching
  • Flexible Switching
  • Dimming Override
  • Timeclock Control
  • Centrally Managed

Daylit Low Occupancy

  • At A Glance
  • Selection Filter

At A Glance

Control
Owned
Shared
Temporarily Owned
Occasionally Visited
Unowned
Managed
Presence Detection
Absence Detection
Photocell Control
Daylight Dimming
Manual Switching
Flexible Switching
Dimming Override
Timeclock Control
Centrally Managed

Selection Filter

Reset Filters
  • Presence Detection
  • Absence Detection
  • Photocell Control
  • Daylight Dimming
  • Manual Switching
  • Flexible Switching
  • Dimming Override
  • Timeclock Control
  • Centrally Managed

Non Daylit High Occupancy

  • At A Glance
  • Selection Filter

At A Glance

Control
Owned
Shared
Temporarily Owned
Unowned
Managed
Presence Detection
Absence Detection
Photocell Control
Daylight Dimming
Manual Switching
Flexible Switching
Dimming Override
Timeclock Control
Centrally Managed

Selection Filter

Reset Filters
  • Presence Detection
  • Absence Detection
  • Photocell Control
  • Daylight Dimming
  • Manual Switching
  • Flexible Switching
  • Dimming Override
  • Timeclock Control
  • Centrally Managed

Non Daylit Low Occupancy

  • At A Glance
  • Selection Filter

At A Glance

Control
Owned
Shared
Temporarily Owned
Occasionally Visited
Unowned
Managed
Presence Detection
Absence Detection
Photocell Control
Daylight Dimming
Manual Switching
Flexible Switching
Dimming Override
Timeclock Control
Centrally Managed

Selection Filter

Reset Filters
  • Presence Detection
  • Absence Detection
  • Photocell Control
  • Daylight Dimming
  • Manual Switching
  • Flexible Switching
  • Dimming Override
  • Timeclock Control
  • Centrally Managed

Adapted from BRE Information paper 2/99 "Photoelectric control of lighting; design, setup and installation issues". © Building Research Establishment Ltd 1999.

Daylight Factor

The average daylight factor is defined as the ratio of internal illumination level to the external illumination level.

It can be defined by the following formula

DFave = T Aw Θ M ⁄ A (1-R2)

Where:

  • DFave is the chosen average daylight factor
  • T is the diffuse visable transmittance of the glazing material. For clear double glazing, a value of 0.7 is realistic
  • Aw is the glazing area
  • Θ is the vertical angle subtended by the visable sky taking in to account nearby buildings and obstructions
  • M is the maintenance factor
  • A is the total area of the interior surfaces (including glazing)
  • R is the area weighted average reflectance. This tends to be between 0.4 for dark walls and floor and 0.6 for light walls and floor.