Energy efficient globes


Ideally the simplest way of reducing lighting costs with downlights would be to replace the inefficient halogen globe with an efficient compact fluorescent (CFL) or LED globe (although the problems with heat loss and multitude of fittings still remain).

Downligths come as 12 or 240 volt, the type must first be identified (majority of downligths are 12 volt). Here is a guide to determine which voltage you have.

240 Volt fittings

Direct globe replacement is straight forward. Replace with a CFL or LED globe marked as 240 volt or GU10.

12 Volt fittings

Option 1.
The simplest option is to replace the standard 50watt dichroic MR 16 globe with a more efficient halogen globe such as an IRC globe (eg. 20 watt Phillips ES - LV halogen IRC halogen globe). These globes can immediately replace any halogen globe and reduce lighting energy requrirements plus reduce fire risk as they produce much less heat than standard halogen globes (light is equivalent to a 35 watt standard halogen). They go some way to reducing lighting costs, but still retain problems of air leakage and number of fittings etc.

12 Volt fittings
The tyype of transformer determines whether you can use a direct globe repalcement. To determine the type of transformer you have
  1. Examine the transformer. The transformer should work if it is
    • an iron core (ferromagnetic) transformer (older style)
    • an electronic transformer and labelled as LED-compatible or
    • the VA rating is equivalent to the wattage of the replacement globe (eg. 10 watt LED requires electronic transformer to have a VA rating of 10 or less)
  2. Trial a CFL or LED globe and see if it works without flickering
If the transformer works with the energy efficient globe, then continue replacing all globes. If it doesn't then consider these options:
  1. Replace the fixture with an energy efficient 240 volt fixture
  2. Install a 12 volt to 240 volt adaptor to install GU10 globes
  3. Replace the transformer with a low load or LED-compatible electronic transformer
  4. Remove the downlight altogether and refitting with appropriate surface mounted fittings and task lighting.
Safety hint: While replacing halogen globes with energy efficient globes eliminates the high temperatures generated by halgen globes and theoretically allows you to reduce the gap in the insualtion up to the fitting itself, there is always the possibility that someone in the future may reinstall a halogen globe!

Energy efficient globes


Things to remember when buying globes

  • Halogen globes do generate a high quality bright light and this can only be reproduced with high quality LED globes
  • CFL globes have a warm up period and can have variable colour rendering from cool to warm light
  • Buy only well known brands
  • LED gloges are coming down in price and are becoming a cost effective option (consider running costs of transformers, heating loss costs and cooling costs in summer)
  • You should go for bulbs that are at least 50 lumens per watt,
  • Select LED bulbs which use Cree, Nichia, Taiwan Edison or similar high grade LEDs. There's a lot of chinese bulbs out there that are cheap and have good light output, but they won't last anywhere near as long as a bulb with the better quality LEDs

Fluorescent tube

Standard T8 36 watt light globes can be replaced with more efficienct T5 globes. However the starter of the T8 fitting is removed and an adaptor is fitted to the T5 globes.
Suppliers

Improved IRC halogen globes eg. 20 watt Phillips ES - LV halogen IRC halogen globe
is available from local retail stores but is approx half the price from Light-online

See table of efficient globes for retalers of various globes.
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