Thursday, 17 January 2013

Saving energy with existing indirect twin-PLL fluorescent lights

Some existing lights use ‘PLL’ tubes a bit like this:

A typical indirect 2 x PLL light is not maximum efficient or bright because there’s virtually no direct light, it relies on reflections inside the fitting. It doesn’t even give any light to the wider ceiling so is not strictly ‘lighting guide 7’ for ceiling-and-upper-wall illumination:

So in my opinion replacing it with something else is not a great loss to the building.

Also replacing PLL fluorescent tubes with T5 is not possible as they have different mountings.
I don’t recommend using LED inserts as these don’t have enough space for a good heatsink and would change the way the light comes out of the light-fitting as LED inserts only shine in one direction, ie either down or up but not both ways which these lights rely on).

Many of those lights are about 2x40W.

The cheapest energy-saving solution is probably to change the whole light for a 3x14W fluorescent fitting with "low-brightness"-profile beam-angle:
These use about 42Watts, usually give slightly more light at desks but customers might not like losing the diffused effect and being able to see the tubes when looking upwards.
These sell at about than £50 for qty.

Or if budget is not tight:

LED panels

These use use 36 Watts
Installers would need to check light is the same, either by customer buying one to trial…
From memory these create about 480 Lux at about 1.2m below lights so it would be best to test the existing light-level 1.2m directly-below a light-fitting to compare (pick a light with middle-aged tubes as brightness varies with lamp-age).
These sell at about £140 for qty

1 comment:

  1. Emergency lighting is so very important when it comes to protection, safety as well as security of your home or business's visitors.

    Emergency Lights


These are just my tips based on experience as a lighting enthusiast surveying sites and speccing energy-saving lighting in hundreds of buildings over ten years, and I know other people will have had different experiences (maybe different products and technologies too) so please feel free to share your own experiences here.