Calculate Energy Efficiency of Lights

It might be hard to find how labels E, D, C, B, A, A+, A++ are actually calculated. Herefore we created a small tool using the documents available from the European Union; regulation No 874/2012 in particular. (Scroll down to get to the actual calculations.)

The columns contain the following information, the first three of which are inputs:

1. Stated power by the manufacturer.
2. A correction factor (with LEDs this is normally equal to one, except if the driving circuitry is separate from the LED).
3. The luminosity of the light (in lumen).
4. The calculated corrected power.
5. The reference power through a calculation depending on luminosity.
6. The Energy Efficiency Index (EEI).
7. The label that corresponds to this energy efficiency index. For example A++ corresponds to an EEI smaller than 0.11 for non-directional lamps (our case).

Do not get too wind up about exact labels. Although the difference in A+ and A++ is still significant in terms of energy efficiency, it does not touch upon lifetime or other aspects of the product.

Go to the Google spreadsheet to play with values yourself. You will see that labels stated by webshops are often not right!