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

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Emergency Lights and T5 Adapters

We are often asked if installers can fit T5 adapters to fluorescent fittings which have emergency function.
If the fittings have some tubes which are NOT controlled by the emergency system (and are standard switch-start) then you can easily convert the switch-start side (just bypass the power-factor capacitor as usual).
But the emergency tube 'side' of the old fitting usually doesn't supply the right power for running a T5 tube adapter without modification of some kind.  While we have quoted for some sites a special T5 adapter with no internal ballast, and fitting a specially-made emergency pack complete with external high-frequency ballast, it costs a lot so tends to provide poor payback.
Solutions
If you can leave the small number of emergency tubes un-converted please remember that our T5 adapters use less power than typical plastic end-cap style T5 adapters (for equivalent ground level light due to the bright silver integral reflector) so across the site you might even find energy-savings are as the customer first estimated a T5 conversion would deliver anyway.
But if it's critical to convert all tubes to emergency you could suggest fitting new bulkhead emergency light-fittings. These are cheap at about £20 each.
Using a non-maintained (always 'off') version saves a little energy too.
Bear in mind that the original emergency battery packs may have been on their last legs anyway so this is a solution that improves the emergency lighting system.
Then when you fit the T5 tube adapters to what was the 'emergency' side of the light-fitting, the qualified electrician would just bypass all the control gear, so full mains voltage is delivered to the T5 adapters.

I'm referring to the ClickSave models. A few T5 adapters may need a different approach.

www.energyatwork.co.uk