T5 fluorescent tubes save energy compared to T8 and T12 tubes, correct?
Well for starters they're more efficient than old-style tubes (I mean the ones that only last a year or two and go progressively yellow and dim).
But be careful because not all T5 tubes are more efficient than all T8 tubes. If you're comparing some of the latest 'tri-phosphor' T8 tubes, total light-output can be similar.
So why do people say fitting a retrofit T5 tube-adapter give the same light for less energy?
Before we can answer that we need to define what a T5 tube-adapter is...
There are two main formats of T5 tube adapter:
One large plastic tube one end, contains the ballast. At the other end is a similar plastic tube (empty) or a small cylindrical cap with two T8-style pins to fit the existing light-fitting (fixture).
- Easier to store and post
- Some have a tendency to sag as there's no end-to-end backplate.
- Lack of a built-in reflector compromises light reaching ground/desk-level so to generate enough light at the ground the whole unit tends to use a little more power than the tube is rated at. (You can often buy a clip-on reflector at extra cost, maybe about £5 for a 5ft version).
- These usually only strike the tube from one end, so it needs a larger 'kick' and we haven't heard of any that feature 'pre-heat' either... this gives a gentle start to tubes making the last a lot longer if regularly started (critical if you have PIRs).
- The end-cap containing the control ballast is sometimes too bulky to fit light-fittings with no clearance either above or below the existing tubes.
- Heat resistant (tubes can't 'stick' inside the adapters)
- Can have built-in reflectors to make maximum use of the light by guiding most towards the ground
- The extra light-efficiency means the unit can be made to run at a lower power and still create enough light at the ground/desks
- Rigid yet light
- For adapting 6ft and 8ft lights two shorter T5 tubes can be used end-to-end
- The best examples have a pre-heat system for longer tube life
- Some brands offer two or even three different profiles of the same lenght adapter, to allow them to fit light-fittings with lack of clearance either above or below the original tube
- All this sophistication can come at a highter price, but this is usually offset by the improved energy-savings as these often use less energy than the end-cap-style adapters
- They are as large to store and move as a T12 fluorescent tube, but that's usually more of a problem for the suppliers than the end-user