MR16 Halogen Light bulbs - are they energy efficient?

I currently moved into a new house with several MR16 20W 12V Halogen spotlights installed. There are around 25 of such light bulbs around the house with 7 in the living room.
I will be using the lighting in the living room for prolonged period of time, at least 9-10 hours per day. I am worried that the running costs of the current lighting set up will prove expensive.

After looking online at various forums, I understand GU10 LED light bulbs are being suggested as an alternative?
In my previous home I had GLS LED 9W bulbs, and one light bulb per room was enough for me.

I would prefer to use those lights again in the new house, however there are no bayonet or screw attachment fittings in the house.
Since it is a rented home, I can not install completely new wiring systems without landlord's permission.

What would you suggest I should do? Are the MR16 light bulbs currently installed use up lot of electricity?

Thank you for your advice.


Just get MR16 LEDs...…NEg

But if you really want to convert, just buy a convertor to the bulb you " like " (screw etc).…ter
Edited by: "soled73" 19th Aug 2016

Original Poster

Thanks soled73.
Whist looking at the ledhut website, it suggested some transformers might not be LED compatible. Is there a way I could check if I look at the transformer that's installed?

I was reading this website, but could not understand it properly.

So for example, I have 5 20W MR16 bulbs installed in one room, so is that 5 * 20 = 100 VA (watts).
Therefore the transformer should be able to handle 33 of the 3W LED light bulbs you recommended?

I know it might sound obvious, but I just want to be sure.


Or just remove some of the bulbs if you aren't going to be in the house long term

Original Poster


Or just remove some of the bulbs if you aren't going to be in the house … Or just remove some of the bulbs if you aren't going to be in the house long term

I have tried that but the rooms seems dark for my needs.
I would be mainly working from home and usually stay until very late at night depending on the work load.
So good lighting is essential to avoid straining my eyes in the long term.

The problem with replacing MR16's is that often the transformer needs a minimum wattage load to operate properly - so in your example with 5 x 20W bulbs the 100W transformer will be marked 20-100W with a minimum of 20W load needed.

If you replace 5 MR16 halogens with 5 MR16 3W leds then you will only have a load of 5 x 3W = 15W which is below the 20W minimum and may mean no lights, flickering lights or the lights turning off after a few minutes.

Depends on the transformers fitted and whether you can access them easily......

Usual way is to replace 4 of the 5 bulbs with leds and leave 1 halogen in place - that way you will have at least a 20W load from the halogen bulb..

I thought you just replaced the transformers for LED drivers on low voltage systems? But yes best thing I ever done was replace my whole lighting to LED, went from like 960w of bulbs to 120w and have far better lighting too...good luck…tml

Looks like "heavy iron" transformers are pretty much guaranteed to work, while some electronic ones may have difficulty.

Leaving one halogen (if it's a single transformer setup) might stabilise a transformer that has difficulty driving a 100% LED load.

20W halogens consume 20W per bulb, so the 7 in the living room would be 140W - or a KWH every 7 hours.
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