LED LLMF....?

[Nick1c]

We are getting to the point where we will be speccing the lighting. The two biggest questions are is it worth investing in a smart (probably Casambi based) system and should we go for integral light engines or GU10 lamps. 
Until yesterday I had come down on the side of the integral option - initially more expensive, but better value in the longer term, Aurora seems to be a popular choice. However a conversation with a wholesaler (who sells both types) has made me uncertain again. Apparently led’s tend to dim over time rather than suffer catastrophic failure, an arbitrary reduction in output of 30% is the point at which they are considered ripe for replacement - this is the lamp lumen maintenance factor LLMF. As I understand it the potential problem occurs if one light on a circuit fails, once it is replaced (assuming spares are available), it will be generating the original levels of light, which will be greater than the older lights on that circuit, meaning that all the units may need replacing to make it even once again.

Another benefit of the GU10 option is that dim to warm is available.

The wholesaler was talking about the ease of upgrading the lights should better technology become available with GU10. 
As someone who is new to, & relatively ignorant of, LED technology I would like to hear the opinions & experiences of those on here who are better informed - GU10 or integral lamps & why...

[Jeremy Harris]

There are a great many more options than just the GU10 downlighter LEDs available.  The main issue with 230 VAC GU10 LEDs is that they are a bodge, in that the base has to contain a shoehorned in LED driver, plus GU10 downlighter fittings were originally designed for halogen lamps, that like to run very hot.  As a consequence, driver failure due to overheating in the base can be a problem with GU10s.  An alternative, in the same front face form factor, is to use MR16 12 VDC LEDs, with an external power supply.  An even better alternative for downlighter type LEDs is to look at using low profile panel lights.

 

We started out with MR16 LEDs in standard downlighters, with a separate 12 VDC power supply.  They are OK, and we still have a few, but I changed all the ones in the kitchen/dining room for flat panel LEDs, and we've found that they give a much better spread of light.  There are dozens of makes of these, all fairly similar, with a choice of light colour.  They also come in a range of different sizes and shapes, ranging from small round ones that are pretty much a direct replacement for standard downlights, to large rectangular panels.  The round 6 W ones are a pretty good compromise, as they are a bit larger than a standard downlight, but still look fairly neat, and they give significantly more light, over a wider arc, than downlights.

 

I made up a test panel and fitted samples of 6 lights to it, with a rotary switch so that I could select each in turn.  This made it easy to compare lights and decide which we wanted.

[ProDave]

I chose the all GU10 LED option.  And in 2 years have not had a singe failure.  I like the ability just by choosing what lamp, to have different brightness and colour.

 

I have fitted (for others) many of the LED flat panel fittings.  They do seem to work very well indeed and give a nice light.  But my concern would be, are they still going to be available in the same size and style in 10 years time?  I would pretty much guarantee the humble GU10 or MR16 lamps will be.  So if I were fitting flat panel fittings, I think I would want a good number of spares just in case.

[MJNewton]

4 hours ago, Nick1c said:

Another benefit of the GU10 option is that dim to warm is available.

 

Being very picky about light quality and fans of the warming colour temp of incandescents this feature is of interest to us too. So far we've only tried two types - Philips Master LED Dimtone and Ikea Ledare. We much prefer the latter in terms of dimmable range, linearity and overall colour rendition. Indeed, Ikea LED bulbs have knocked spots of all the Philips varieties we've tried so far (half a dozen or so, including one from their Expert Color range) and they generally have a >90 CRI so really do represent decent quality bulbs in my view. The only issue is that some of the ones we tried are no longer available and whilst replacements are creeping in they look physically different and so presumably are different so I am crossing my fingers they are still as good (haven't bought any to try out yet).

[Nick1c]

Have any mid-long term led users changed a single light on a group circuit and either noticed (or not) a different level of light from new to old? 
While GU10 leds may well have initially been  replacements for the halogen lamps as @jsharris suggests presumably by now the housings are being designed to keep the lamps cool, reducing unreliability. 
It doesn’t appear that MR16 (GU5.3) is a simple option, as far as I can see you need to choose the luminaire, lamp holder, lamp & transformers individually, is it worthwhile?

[MJNewton]

7 minutes ago, Nick1c said:

While GU10 leds may well have initially been  replacements for the halogen lamps as @jsharris suggests presumably by now the housings are being designed to keep the lamps cool, reducing unreliability.

 

Many GU10 housings, even fire rated ones, are completely open-back these days so should prevent heat build-up e.g. Integral's Evofire range:

 

 

That said, perhaps integrated fittings might be better able to exploit the benefits of integrated heat sinks to improve cooling even further, as well as move the electronics further away from the LEDs.

Edited March 5, 2020 by MJNewton

[Nick1c]

My main concern is the loss of lumens over time with any of the solutions (integrated, GU10 or GU5.3). If this is noticeable in real life  the cost of replacing defective units changes significantly & pushes my decision towards separate lamps. 
The wholesaler also thought that it would be easier to take advantage of future developments with separate lamps as they felt the fittings are here to stay. 

[Jeremy Harris]

I've had LED lighting installed in this house, and in our old house, for several years now.  I've not noticed any loss of illumination at all.  The older CFL lamps that I replaced with LEDs in the last house definitely did reduce in light output after a year or two, though.

 

My experience has been that LEDs seem to fail pretty catastrophically when they do fail, and either just stop working or sometimes one or more LEDs in an array will die, creating a dark spot.  I've yet to see any failures in this house, and all our lights are LED.  Most have been in and working here since fairly early in the build, so are now around 5 years old.  We've had one failure, a small, "filament" type globe LED lamp that I fitted to a Tiffany bedside table light.  That failed about a month after I fitted it, and I replaced it with an identical spare and it's worked fine since.  Most of our LED lights are fairly inexpensive ones.  The standard "bulb" type ones came from Screwfix (none have failed yet) and the panel lights in the kitchen/dining room ceiling came from China (they were dirt cheap, so I bought far more than needed, so have loads of spares).  The only problems I had were with a mismatch between some 12 V drivers and some MR16 LEDs, that was caused by the drivers being designed to run halogen lamps.  It turned out that they delivered high frequency (~20 kHz) "AC" (really a pulse train) that upset the slow rectifiers in the MR16 LEDs.  Changing to 12 VDC drivers fixed that problem, and also got rid of some bad radio interference that these drivers created.

[Ferdinand]

3 hours ago, Nick1c said:

My main concern is the loss of lumens over time with any of the solutions (integrated, GU10 or GU5.3). If this is noticeable in real life  the cost of replacing defective units changes significantly & pushes my decision towards separate lamps. 
The wholesaler also thought that it would be easier to take advantage of future developments with separate lamps as they felt the fittings are here to stay. 

 

I have had LED GU10s in since 2013, and I still have a pile of original spares because they just don't pop very often.

 

I have not noticed a loss of brightness either.

 

The one problem I have noticed with LED bulbs is getting big ones over say 100W. The type with the strings of LEDs seem to cost more and go pop more often in my experience.

[Temp]

The main issue with GU10 in my experience is that when one or two fail you discover that make and model are no longer made or no longer identical. 

 

The other issue is that I much prefer wide beam angle bulbs >90 degrees and most companies seem to be moving to narrower angles like 36 degrees. In my opinion this makes them too spotty and not uniform enough. If that trend continues flat panels will be a better bet for many applications if not already.

[Carrerahill]

20 hours ago, Nick1c said:

We are getting to the point where we will be speccing the lighting. The two biggest questions are is it worth investing in a smart (probably Casambi based) system and should we go for integral light engines or GU10 lamps. 
Until yesterday I had come down on the side of the integral option - initially more expensive, but better value in the longer term, Aurora seems to be a popular choice. However a conversation with a wholesaler (who sells both types) has made me uncertain again. Apparently led’s tend to dim over time rather than suffer catastrophic failure, an arbitrary reduction in output of 30% is the point at which they are considered ripe for replacement - this is the lamp lumen maintenance factor LLMF. As I understand it the potential problem occurs if one light on a circuit fails, once it is replaced (assuming spares are available), it will be generating the original levels of light, which will be greater than the older lights on that circuit, meaning that all the units may need replacing to make it even once again.

Another benefit of the GU10 option is that dim to warm is available.

The wholesaler was talking about the ease of upgrading the lights should better technology become available with GU10. 
As someone who is new to, & relatively ignorant of, LED technology I would like to hear the opinions & experiences of those on here who are better informed - GU10 or integral lamps & why...

What your wholesaler has tried to explain to you is true but the GU10 will cause more grief over time and also suffers lumen loss. A domestic downlight will probably average about 300-500Lm - so say a reduction of 30% (L70 I'd suggest if after 50,000hrs) so 150Lm loss, at that you would be hard pushed to actually see a difference albeit yes it would be there. The fact your wholesaler seems to well versed in this suggests that the integrated products they are selling are not very good and thus this issue is rearing it's ugly head too soon.

 

I was on a site that had been handed over to the client 2 weeks ago, reception staff complained their desk was too bright, we had run the calcs and inline with CIBSE guides had designed the reception to 300Lux Avg with uniformity greater than 0.6. So in we went one evening with a light meter (only way to measure light in rooms with natural daylight penetration) and took a reading, on the desk we got readings of 250-350lux - fine, CIBSE LG07 would recommend 300-500lux for office spaces depending on use, so even allowing for the peak area of 350lux it was still well within spec, what I suggested the problem really was was the high gloss white reception desk reflecting light into her eyes! We rolled out a piece of cardboard immediately the issue was gone! However, on the lead up to this I advised the electrician to go into the fitting, and turn down the drive current from 1050mA to 750mA - now I didn't have the current/lumen curve so I don't know what lumen reduction that would have resulted in but at a 300mA drop we couldn't "see" any light drop - we eventually dropped it to 500mA and we began to notice it if we looked, others still could not see a drop - the humen eye is actually not that good at these relatively small light changes.

 

The issue I have with GU10 is the little "driver" it is often no more than a cap and a resistor and some other bits, prone to being inefficient, getting hot and potentially being a big of a weakspot as the "driver" circuit usually fails before the LED.

 

Aurora, JCC, Enlite etc. are "popular" among contractors as they are cheap and cheerful, you will generally not find Aurora speced on a job unless it was D&B or contractor lead - do not get me wrong I think they do fine, but as I see it they are really only suitable for the domestic market and often the optics and distribution is a bit rough. 

 

So most LED products that we would spec would be L90 - 100,000 - very basically it means that the LED will output 90% of it's initial lumens for 100,000hrs. L90 industry standard was always 50,000 - so if someone quotes L90 with no figure after it then it is only 50,000. You will also get L80, L70... 

 

Now even at 50,000hrs that is 11.41 years at 12 hours a day! 

 

So if the wholesaler is telling you about 30% lumen loss, then just how soon are they expecting this drop that you would start to individually replace lights? If I got say 15 years out a set I would probably be happy to replace it with the 2035 version which is 0.5W for 500Lm!

 

Something to bear in mind is that all light sources degrade with time, florescents were terrible for it, people just saw they lit up and assumed they were fine but in fact they were well beyond their service life and could be as low as 50% of original lamp lumens. 

 

The high quality range of LED downlights use an LED engine/module which can be changed out, the Aurora units are largely all glued up and sealed - once dead, you bin them.

 

A nice option for dometic installs is to buy a nice GU10 downlight and then buy the likes of a Tridonic LED engine and driver. You end up with a cost effective product with the light output and quality of for example a Flos or Erco down light which can cost £200 each!

 

Like this:

 

 

Note it has a decent heat-sink on it and optic etc. all built in.

 

You can get a nice downlight for about £12.00-£15.00 and the Tridonic module and driver is about £15.00-£20.00 depending on lumen output - also, try and stick to around 3000K unless you want a white commercial feel.

 

 

 

 

 

 

 

 

Edited March 6, 2020 by Carrerahill

[joth]

6 hours ago, Carrerahill said:

then buy the likes of a Tridonic LED engine and driver.

Excuse the ignorant question, but is the driver built into the unit pictured or is it a separate?

Afaict the tridonic LEDs take 220V in so not sure what sort of driver you'd add. (Dimmer aside)

 

[Nick1c]

Thank you @Carrerahill, that is very helpful. 
Having read this I reconsidered one of the first manufacturers I came across (Chiara) as they use that modular design. Unfortunately the model I had been considering requires a depth of 125mm, & I will have a maximum of 112mm available. This made two things come to mind:

- The tridonic unit you have shown is, I think, the one they use & has the electronics & light generator in the same unit, I have seen some where the two elements are separate, allowing the electronics to sit off to the side. This arrangement allows for less headroom, are there any downsides to these units?

- Glare. Is this principally managed via the reflector in the lamp or the position of the lamp in the fitting? The higher the light generator sits in the fitting the narrower the cone of direct light, but there is the possibility of it bouncing off the internal walls of the luminaire to create a more diffused light? 
 

I believe the bathrooms need IP65 lights, which I assume require more headroom.....
 

There seems to be a wide variation in quality (not necessarily related to price) & a paralysing range of choice in lights. Any pointers as to where to start looking would be useful!

 

[Mike]

On 06/03/2020 at 15:22, Carrerahill said:

nice option for dometic installs is to buy a nice GU10 downlight and then buy the likes of a Tridonic LED engine and driver. You end up with a cost effective product with the light output and quality of for example a Flos or Erco down light which can cost £200 each!

Hi @Carrerahill - I'm reawakening this thread as I like the idea!

 

Do the Tridonic modules clip in place using a standard spring clip (similar to the type normally used to retain GU10 bulbs)? Or at least can they be changed from below without disturbing the fitting?

 

I ask because I'm planning to use some plaster-in downlighters, so removing them to fit or change a light engine would be... very problematic.

[Carrerahill]

On 03/02/2023 at 22:27, Mike said:

Hi @Carrerahill - I'm reawakening this thread as I like the idea!

 

Do the Tridonic modules clip in place using a standard spring clip (similar to the type normally used to retain GU10 bulbs)? Or at least can they be changed from below without disturbing the fitting?

 

I ask because I'm planning to use some plaster-in downlighters, so removing them to fit or change a light engine would be... very problematic.

Yes they do. However, there are some brands which are plaster in, but still have a retaining ring which permits removal of the LED engine & driver from beneath. I'll find out who they were as I spec'ed them on a hotel project last year.

 

 

[Carrerahill]

On 03/02/2023 at 22:27, Mike said:

Hi @Carrerahill - I'm reawakening this thread as I like the idea!

 

Do the Tridonic modules clip in place using a standard spring clip (similar to the type normally used to retain GU10 bulbs)? Or at least can they be changed from below without disturbing the fitting?

 

I ask because I'm planning to use some plaster-in downlighters, so removing them to fit or change a light engine would be... very problematic.

https://ledsc4.com/en/collection/play-0

 

LEDS C4 Play - all accessible from below. Proper LED engine version available.

Edited February 6, 2023 by Carrerahill

[Mike]

Thanks @Carrerahill, that very helpful :)

 

Sounds like it could well be the way to go.

[PaulD]

I'm also at the early stages of design, and I'm investigating the extensive use of plastered in LED strips. Apparently dotless strips with good quality drivers. I'd be interested in knowing if anyone has used these as their primary lighting source, as well as mood lighting of course ? I've attached a pic found on google and initial render from my kitchen designer. Will also be using them vertically in walls.

 

 

 

[Temp]

Wish my dad was still alive. He was lighting engineer/manager at BBC and could probably make a fortune designing lighting for houses. He did some garden lighting in the 1980s tor people but was getting offered projects on £ multi million houses and was meant to be retired.

[Temp]

Im not a lighting engineer but my guide/sanity check for kitchens goes like this... lighting experts look away now :-)... 

 

Google recommends about 500 lux for a food preparation area.  500 Lux = 500 Lumens/sqm.

 

Our kitchen is about 4x3.5 = 14sqm so my rule of thumb says we needed 14*500= 7,000 Lumens in total. We fitted 15 led rated at abut 400-450 Lumens each. That works out at about 6500 lumens. We're happy with the result but its just a simple grid of LED down lights. I choose wide beam angle bulbs to eliminate shadows and "spotty" lighting but at the expense of a bit of glare.

 

LED Lighting tapes/strips typically quote "Lumens per meter" in the specification so you can  get a rough idea how many meters of linear lighting you would need in that central rectangle. 

 

Experts will tell you this is all wrong and that beam angles, ceiling heights and the emissivity of walls matter.. but if your lighting designer says you need a very different figure for the total Lumens you can at least ask him to explain how he arrived at his figure. If he can justify it then he's probably right.

 

You might find a company that will do you a lighting design "free" if you buy their lights?

Edited August 15, 2023 by Temp

[Mike]

On 15/08/2023 at 15:44, PaulD said:

I'd be interested in knowing if anyone has used these as their primary lighting source, as well as mood lighting of course ?

I've seen some pics on here before, so you're not the first, but too long ago to remember all the details. I have a feeling they were in a hallway though?

 

I'm likely to fit a single strip as the main lighting in my galley kitchen later this year. Mainly on the grounds of practicality - there will be too many MVHR ducts and cable runs in the ceiling to fit decent downlighters, and I don't want anything projecting down to block the wall unit doors. Though I've not entirely ruled out a concealed strip.

 

Add LED strip with a high CRI (Colour Rendering Index) to your list of requirements - that is, a CRI of at least 90.

[markharro]

Slightly random addition to this thread but I am currently trying to work out the lighting for our utility room. The room is about 5m x 1.5m but it has a very high ceiling (3.5m). I "asked" Chat GPT and got this - 

 

Certainly! Let's adjust the calculation for a room with a reduced area of 8 square meters, a height of 3.5 meters, and aiming for an illuminance level of 500 lux:

Room Volume (cubic meters)=Room Area (square meters)×Height (meters)Room Volume (cubic meters)=Room Area (square meters)×Height (meters)

Room Volume (cubic meters)=8 square meters×3.5 meters=28 cubic metersRoom Volume (cubic meters)=8square meters×3.5meters=28cubic meters

Now, use the illuminance formula to calculate the required lumens:

Lumens=Illuminance (lux)×Room Volume (cubic meters)Lumens=Illuminance (lux)×Room Volume (cubic meters)

Lumens=500 lux×28 cubic meters=14,000 lumensLumens=500lux×28cubic meters=14,000lumens

So, for a room with a reduced area of 8 square meters, a height of 3.5 meters, and aiming for an illuminance level of 500 lux, you would need approximately 14,000 lumens of light. Adjustments can be made based on specific room characteristics and lighting preferences.

 

14,000 lumens sound like a lot so I thought I would ask what some of the experts on this thread thought? If its relevant I am planning to fit 3 flush ceiling lights (probably LED panels) then we will have a couple of directional wall lights lower down.

 

thanks

[JohnMo]

Just put in 2 or 3 125 to 150mm round flush fit led on the ceiling, job done.

 

5 x 1.5m is more like a small corridor, you will get plenty of light bouncing if the walls to make it bright. 

[Mike]

20 hours ago, markharro said:

Lumens=Illuminance (lux)×Room Volume (cubic meters)

Ignore!

 

Height does play a small factor, but floor area is the biggest factor by far.

 

20 hours ago, markharro said:

I am planning to fit 3 flush ceiling lights (probably LED panels) then we will have a couple of directional wall lights lower down.

Doesn't sound unreasonable for a utility room.

[Temp]

We have a similar size utility room. It's slightly more square and 2.8m ceiling.

 

We have a single 3600 lumnen LED batten in the middle. It's one of these...

 

https://www.amazon.co.uk/gp/aw/d/B07WMMLJFZ?psc=1&ref=ppx_pop_mob_b_asin_title

 

Plenty bright enough.

 

The only issue with that particular model is it's designed to be linked together so the  power goes in via a socket on the end rather than just a hole on the top.  

 

I think you will be fine with two panels around 2000-2500 lumens each.