Thursday, January 20, 2011

Improving energy efficiency: LED downlights

A 12V halogen example
I’ve been watching developments of LED lighting for some time, not least because my home has more than 20 of those stupid 12V recessed halogen downlights (illustrated, right), that are a fire hazard and not a very efficient way of lighting a whole room, even allowing that 50W of halogen lighting isn’t a lot of lighting compared with a few watts of LED. Why is a ceiling full of spotlights a better way of lighting a room than one or two lights with a wide spread, I ask with tears in my voice?

One of the obstacles to replacing them is mine have an electronic transformer creating the 12V DC these things need (a small fraction use AC, and I replaced those, though with LEDs that aren’t that bright).

Last night, one of the 12V models failed again, so I decided it was time to reopen my look at LEDs. Some have appeared on the market that have better electronics and can tolerate electronic transformers, but they aren’t cheap. On one web site with prices, replacing all of mine would cost over $700.

It would probably make more sense in terms of cost to pull all of them out and replace them with sensible fittings but I’d like to explore LED options a bit before going that way.

I will add to this article as I find out more, but if anyone has hints or insights, please post comments.


  1. Phil, I know that Ngaire from Sustainable Jamboree has a bunch of LED lights at her place. She was giving quite detailed explanations about them on sustainable house day. Perhaps she might have some insights?

  2. Thanks, I'll see what Ngaire can tell me. Something else occurred to me: if we have a house with photovoltaics and battery backup, and a high fraction of household appliances work on 12V or less, why not have a low voltage circuit around the house you can plug into directly (possibly with cleverly designed sockets that depending on the plug connect you to one of a choice of voltages)?

    Taking that as a starting point could lead you to a very different house. It seems to me a bizarre inefficiency that we convert everything to mains voltage, then a lot of our usage requires a transformer and rectifier to DC, when at least some of our sources are relatively low voltage DC already.