Yes, Alan is of cource once again right.

Lutron estimates 20% for transformer loss (MLV)
Vantage estimates 30% (for MLV)
Another system we do advices us for 10% (for ELV)

Alan do both kind of transformers (magnetic and electronic) waste energy? Aren't the electronic ones a bit more efficient?

Advice on electronic transformers:
First check if the transformer is dimmable.

Then check if it is dimmable by leading or trainling edge dimmers- usually good transformers indicate this on their casing: dimmable by leading and trailing edge dimmers.

If you only see on the case "dimmable" there is a big chance the transformer is not very good and of questionable (not good quality) origin.

If there is nothing written on the case about dimming, change transformer. You will almost certainly have problems if you try to dim this.

Connect the transformer and see if the buzzing is bearable. If there is a lot of buzzing from the transformer or the dimmer this probably means that the transformer is not good and that it will fail after a few months (this really happens). Also obesrve the lamp when you dim and fade up and see if the process is natural.

Do not use trailing edge transformers on a leading edge dimmer. They will gradually fail or even not work at all.

Homeworks is a leading edge system but there are modules (HRPM4A, GXI3504, NGELVI) that can be used with trailing edge transformers.

The best transformers we have tried and the most silent ones are the Lutron ones, but they are quite expensive.