Are we talking about during the heating season or during the time when no heating is needed?

Are you interested in just the amount of light (lux) per watt or how good it is when fitted into a home. There seems to be a big difference between what is produced in the lab and what is produced in your living room.

ST, lux is another measure for Lumen I presume.

Posted By: SteamyTeahow good it

What do you mean by that ST? 'Good' in the way you put it, is IMO a function of the user! That is, getting the right angle on the beam; the right colour; the right location; and understanding ambient, display, task etc.

To me Lumen per watt is the first thing I look at (from a green perspective). It seems in retro fit lamps eg GU10 100lm/w is now the 'norm' for high performance. For all in one fittings (are they called luminares?) where you just plug into 240V, 50-75lm/w is the range I am finding. Where possible (not often) a fluorescent tube still seems to have the edge yet LED replacements for fluorescent tubes are available, why?

ST is absolutely right that it matters where the light goes in a room. More of that in a moment.

However, if you are comparing fittings, a good start is to measure how much light comes out in relation to the electrical power that goes in. That is measured in lumens per watt.

Efficient LED chips can be let down by an inefficient power supply unit or a light fitting (luminaire) which absorbs a lot of light before it reaches the room. For this reason it is good practice to specify 'luminaire lumens per circuit watt' for the light fitting and PSU taken as a whole. This figure will always be less than the rating for the bare LED chips or LED 'bulb', but at least you know that a 60 LLPCW fitting which draws, say, 7 watts of mains electricity will put 420 lumens worth of light into the room.

By the way, the human eye is most sensitive to green light and least sensitive to deep red and violet. The definition of the lumen allows for this, so a 500 lumen warm white fitting and an otherwise identical 500 lumen cool white fitting should have the same subjective brightness. Cool white LEDs generally deliver more lumens per watt than the warm white equivalent, so cool whites of the same wattage will be subjectively a little brighter. But it's a small difference. Your priority should be to get the atmosphere you want, and match any other light sources in the room.

Choosing efficient fittings is important. But lighting design - choosing suitable types of fitting and positioning them to deliver the lighting you want - is really, really important. You see rooms, with recessed spotlights all over the ceiling, which still feel *dark*. That's because the light shoots straight down into the floor which, depending on the floor covering, may absorb up to 90% before it has lit anything useful. You only see anything when a party guest with sparkly jewels steps under the light. OK for ballrooms, but not for your average living room where it might be better to instal tiltable spotlights 500-600mm from the walls. There they can wash the walls with light (which then floods the room) or usefully illuminate shelves and pictures. Just one example, will stop there

Posted By: rhamduwill stop there

please don't! (and my posting overlapped yours)
Surely a GU10 bulb is a What You See is What You Get (WYSIWYG) thing as PSU is integral, most such fittings have the bulb fully exposed (no shading), operates within temp range so nil impact on the lm/W? Same with a 240V input LED luminaire with defuser - ie 240 volts in, light comes out of fitting through its fitted defuser, volts in and Lm out as per spec sheet - WYSIWYG. Hope so because I have never seen LLPCW on a spec sheet before!

So for a 240volt in luminaire with diffuser what's a goof lm/W and for a GU10/screw fitting 240volt bulb, what is a good Lm/W? Remember, us ordinary people just buy a 240 Volt luminaire or a GU10 fitting and a LED GU10 bulb.

And the original question, which I repeated - are fluorescent Tubes still more efficient or 'better' in some way compared to LEDs?

>In many cases, in field rather than lab conditions, high frequency driven, efficient phosphor T5 with daylight ?regulating still outperforms LED (often significantly) in terms of energy consumption.

And in many cases probably gives a 'better' light in terms of colour rendition? The advantages of LED should be life and reduced fragility. Old style linear tubes always seemed to last for ages though. Even my expensive, high quality, compact fluorescent bulbs seem to have a terrible failure rate.

I completely agree about the ceiling spot downlights - if I had my way they would virtually never be specified in domestic settings. My aim would usually be to combine some more diffuse pendant lights with uplighters and/or concealed light sources.

I also get the point about the amount of light coming out of the luminaire being different from the light output of the lamp itself. However as others have commented it seems difficult to find this specified.

At the moment I'm looking for some linear type light sources which will be concealed (ie the light fitting itself will not be directly visible). So the choice is between something like a T5 and equivalent LED striplights. LED striplights for this kind of situation seem to be increasingly popular, but I wonder if that's more to do with size than efficiency.

Posted By: GotanewlifeSurely a GU10 bulb is a What You See is What You Get (WYSIWYG) thing as PSU is integral, most such fittings have the bulb fully exposed (no shading), operates within temp range so nil impact on the lm/W?

All good points. But the bulb may not be fully exposed in fire / acoustic / IP-rated (bathroom) fittings. Also you may want a baffle to prevent glare. And there's Barney's point about ULOR - upward light is wasted in a recessed fitting, but not totally wasted in a surface fitting.
It remains true that if you have two bulbs of the same physical shape and the same beam angle, but one has higher lumens per watt, you can expect that bulb to keep its performance advantage when the two bulbs are put in identical fittings.

Posted By: GotanewlifeLED replacements for fluorescent tubes are available, why?

It's not always just about efficiency. I put compact fluorescent overhead in my kitchen, but swapped some out for LEDs sharpish. The CFLs took too long to warm up. In some places and for some jobs you want instant light. So for that you always want LED over fluorescent.

Posted By: GotanewlifeIt seems in retro fit lamps eg GU10 100lm/w is now the 'norm' for high performance.

Got any examples of that, please?

Posted By: SteamyTeaThe new cheap 8W ones from MacSalvers (a strange Cornish store) do not seem to have a warm up time

There's a compromise between the expected life of the lamp and the time they take to warm up. So the manufacturers make versions with different components in the control circuits. The often-called 'instant start' ones come on quickly but won't last as long. The slower starting ones (which get the tube to the optimal conditions before starting) will last longer.

So it depends if you want instant gratification or a long life!

Posted By: djhGot any examples of that, please?

Below quote from last junk E Mail from one of the lighting people I use they call it a "Newsletter from www.uklightbulbs.co.uk" and heavily edited it says:

"We believe to have (sic) the best..blaaaaah...We now have stock of these with BC, SES AND ES caps...blah...60SMDs...blah...The GU10 version we have is the best to date we found...blah...Power 240v 3watt Lumen light output of white 420Lm Aluminum Construction Glass Lens".

I nearly didn't read the killer line at the bottom, but it made me sit up when I did. I'm afraid the IKEA ones aren't even half as efficient.

Posted By: CWatterspaying attention to the beam angle

ditto, in retrofit beam angle v important to get result you were expecting.

Posted By: lineweight(The Sylvania one actually has a shorter claimed lifespan than the unbranded one)

Probably to preserve reputation and limit warrantee claims.

The best LEDs are better than the best flourescents. Most LEDs are still worse than good flourescents in simple lm/W terms. Rhamdu gave lots of good advice, but I disagree that "it's a small difference' between cool and warm white. It varies between 10% and 30% difference. Newer devices possibly showing less difference, from a quick perusal of http://www.leds.de/en/High-Power-LEDs/Cree-High-Power-LEDs/

As you can see from that table bare LED lm/W varies from 23 to 158. I wouldn't buy anything under 100lm/W these days. But this is ignoring luminaires and optics which make a big difference, as explained. I just put very efficient LEDs behind a simple diffuser with a decent (> 85% efficiency driver) and find it makes very nice room lighting. I have no idea what luminaire lumens per circuit watt I am actually getting as I have no facilities to test the optical efficiency of my luminaire.

Has anyone tried just stringing LEDs all the way round the outside of a room for general lighting? This seems to me light it ought to work well (along with a bit of task lighting), but I've not actually got round to trying it yet.