Useful Lumens Guide

The term 'Useful Lumens' is a new term dreamt up by the EU as a means to try to stop poor quality directional lighting (spotlights and GU10s) appearing on the market.  

Some years ago it was looking like the LED market's reputation was going to be destroyed by the onslaught of cheap poor quality GU10 lamps that were making wild claims about the lifetime and the output, duping consumers into buying what they thought was a great GU10 bulb only to find that it was terrible.  This then led to the reputation of LEDs to start falling because most people that purchased these lamps were put off by the technology.

On the 12th December 2012, the EU introduced commission regulation (EU) No 1194/2012, which in turn introduced the term 'Useful Lumens'.  Now you will have to bear with us at this point because it becomes complicated but we will endeavour to un-complicate it for you in this article, so the document 1194/2012 defines it as follows:

'Useful Luminous Flux' (what we call useful lumens) means the part of the luminous flux of a lamp falling within the cone used for calculating the lamp's energy efficiency in point 1.1 of Annex III.

So Annex III defines it further as:

- Directional lamps with a beam angle ≥ 90° other than filament lamps and carrying a warning on their packaging in accordance with point 3.1.2(j) of this Annex: rated luminous flux in a 120° cone.

- Other directional lamps: rated luminous flux in a 90° cone. 

So that is the technical explanation, let us tell you what this means in terms of lighting and LED light bulbs.

Essentially what this regulation does is separate the wheat from the chaff when it comes to directional LEDs.  Below is a series of diagrams that we have drawn up for you to explain what this means.

Firstly consider, for example, an LED GU10 lamp.  It throws light forwards in all angles:

As you can see there is light sent out in all directions forward.  Initially when GU10 LEDs first came out there were thousands of different types of LED GU10 bulbs that were making spurious claims about equivalent wattage and although technically correct really did no justice to how great an LED GU10 could be.  Take a look at the example below:

These bulbs both may have the exact same lumen value however as you can see the beam and in turn the light output is very different and can make a huge difference in your room lighting.  LED bulb (a) has a beam angle of over 120° and LED bulb (b) has a beam angle of 40°, however both LEDs have the same lumen value (total light) in this example of 400 lumens.

To understand lumens better click here to read our article on Lumens.

In the example above, LED bulb (a) would not be suitable for directional lighting, it would only be suitable for perhaps general high up lighting.  LED bulb (b) would be suitable for accent lighting, for general lighting and for bar lighting.  How would you tell just by looking at the box?  Would the retailer be able to tell you?  I'm unsure that if you walked into your supermarket that they would be able to help.  So the EU stepped in an made this regulation about useful lumens, because not only is it removing the poor LED GU10 and LED directional lamps from the market, it is also guiding you to the right purchase for your lamps.

Useful lumens now means that we aren't interested in the light that goes off in a sideways direction, we are only interested in the light that would be if you drew a 90° cone in front of the LED GU10.  Here is the image above with this 90° cone:

As you can see there is a lot of wasted 'spill' light from the sides of the light bulb (a) but not from light bulb (b).  Most of the light from light bulb (b) is forward and so when it comes to the 'Useful Lumens' value, this will be higher.  As most of the 'Lumens' is caught within this 90° cone, nearly all the 'Lumens' will be 'Useful Lumens'.  So in this example, for both LED bulbs with 400 Lumens, LED GU10 bulb (a) will have a 'Useful Lumen' value of 200lm, and LED GU10 bulb (b) will have a 'Useful Lumen' value of 300lm.

The EU kindly have laid out what this means in equivalence value, or what your LED might be similar to if it was compared to a halogen GU10 bulb.  This is laid out in the following table:

As you can see from the table above, in our example, LED bulb (a) would only be able to be classed as a 35W equivalent GU10 under these new laws, however LED bulb (b) would be able to be classed as a 50W equivalent GU10, despite both LED lamps having the same 'Lumen' value, they have completely different 'Useful Lumen' values.

In conclusion, it is vital that you ensure that when you are purchasing LED spotlights you check the lumen value to make sure that it is the 'Useful Lumen' value, as getting it wrong could prove costly.  If you are unsure then please check with the person selling it.  If you get it wrong then you may be stuck with a dull, dim light bulb when you could be getting a brilliant bright LED.

For reference purposes the following table is a list of all the equivalent wattages for all the different types of directional light bulbs: