Office Lighting

T5 Fluorescent Tubes

One of the most cost effective energy saving solutions for office lighting is the use of T5 Fluorescent Lighting.  The designation T5 relates to the size of the tube.  T5 tubes are five eighths of an inch in diameter.  They are easy to distinguish because they are much thinner than the older generation fluorescent tubes.

T5 fluorescent bulbs produce up to 100 lumens per watt, while being relatively inexpensive.  One can typically expect a 20-40% saving when converting from the older T8 tubes.

Unfortunately T5 tubes don’t fit into the older T8 fittings. An adapter is required if you don’t wish to replace the light fitting.  Most adapters include a built in electronic ballast.  Electronic ballasts are far more efficient and longer lasting than traditional magnetic ballasts used for older fluorescent tubes.

50W Halogen Downlighters

A particularly problematic light type when it comes to energy saving is the ubiquitous 50W halogen downlighter.  They have the following drawbacks:

  • A single downlighter doesn’t fill a room with light.  Its light is concentrated in a narrow bean shining straight downwards.  This means a large number of lights have to be used to get even light distribution in big rooms.  At 50 watts per downlighter, that quickly adds up to a large load, much larger than is necessary.
  • Halogen lights are very inefficient.  The bulk of the energy consumed is given off as heat.  Apart from the waste of energy, all that heat can cause problems.  Small enclosed rooms such as bathrooms, that need the lights on during the day, can become very hot in summer.  It may even become necessary to add additional airconditioning just due to the lights.  The heat given off by each downlighter also tends to eventually discolour the ceiling paint work.
  • Once all the holes have been cut in the ceiling it becomes impractical to convert to other more efficient light fittings.  There are CFL and LED downlighter alternatives available that will fit into the downlighter fittings, but they are very expensive in comparison, especially if a large number are required.

So 50W halogen downlighters are a very bad choice of lighting for any building from an energy efficiency point of view.  If you are building from scratch, then you should avoid them at all costs.  If you already have them, consider just switching them off and fitting T5 luminairs in those rooms instead. If they are required for aesthetical reasons, then you should keep their number to an absolute minimum, and consider LED or CFL alternatives.

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