After some discussion on power-hungry low-voltage halogen downlights in the comments section of my [We Now Have Solar Power](http://green-change.com/2009/05/18/we-now-have-solar-power/) post, I thought it was high time I did something about them. CFL downlights seemed like the logical replacement.
A while ago I measured that our 50W halogen lights are actually drawing 65W each – the extra 15W is lost in the transformer. So a string of 4 lights uses 260 Watts! We have about 30 of these downlights throughout our house. Ouch!
As part of the [Sustainable Illawarra Super Challenge](http://www.sustainableillawarra.com.au/The-SuperChallenge.html) we’re participating in, we got $100 worth of vouchers for energy-efficient lighting solutions from Cosmo Lighting (Shop 3/9-11 Princes Hwy, Albion Park Rail ph 4257-9111). Serge (the company director) was really helpful, and spent a lot of time showing me the options for converting halogen downlights to something more efficient.
There are three main options for making halogen downlights more efficient:
– **Use lower wattage halogen lamps.** It’s kind of obvious, but I could have replaced some of the 50W halogen lamps with 35W halogen lamps, and saved 15W per downlight. There are new Infra Red Coated (IRC) lamps that claim to give the same light output at 35W as a normal 50W lamp, so I could have even used 20W IRC lamps for some areas and 35W IRCs where the extra brightness is needed. This is an easy thing to do, since no fittings need to be changed, but the IRC lamps cost more and the energy saving is not huge.
– **Use LED lamps.** You can now get LED lamps that fit into the same fittings as halogen downlights, but use as little as 3W. It sounds great, but most transformers designed for halogen lights work best under a 35-50W load. When run at just 3W, their output voltage increases and they’ll greatly shorten the life of your LED lamps. This is not a good thing, as 3W LEDs (equivalent to 20W halogens) cost around $50 each, and 6.5W LEDs (equivalent to 35W halogens) cost over $100 each! To get around this problem, you need to buy and install new transformers specifically designed for LEDs.
– **Convert the fittings to 240V and use Compact Fluorescent CFL downlights.** You can pull out the 12V transformers and wire in GU10 kits, which provide a 240V plug for lamps but use the same downlight fittings to hold the lamp. You can then install 11W or 13W CFL downlights (a 13W CFL is roughly equivalent to a 50W halogen in terms of light output). This option currently gives the best bang for the buck – it uses twice the energy of a 6.5W LED for the same light level, but costs under $10 for the kit plus about $3-10 for the CFL lamp (depending upon brand and brightness).
I was talking to Serge about some of the stuff we’d been doing (and were planning) to reduce our energy consumption, and he really wanted to help me out. In the end he gave me an awesome price on 10x GU10 downlight kits, 6x 11W CFL lamps and 4x 13W CFL lamps.
So today I got up in the roof and changed some fittings over. It’s a pretty simple process, but if you’re not qualified you should get an electrician to do this for you.
I chose our most-used lights for this – 4 in the loungeroom, 4 in the dining room, and 2 in the play room. The dining room is where we need the most light, for when the kids are doing craft etc at the table, so that’s where I put the 13W CFL downlights. I decided not to change anything in the kitchen for now – even though we use those lights a lot, we want it bright in there so you can see what you’re doing, so I didn’t want to risk it for this first trial.
>Tip: Before you get up in the roof, pull the globes out of the fittings you want to convert. This makes it much easier to find the right ones when you’re up in the roof!
Then I just had to wait for nightfall so I could test them out.
The verdict? We’re pretty happy with them. We made the right decision putting the 13W lamps in the dining room. The 11W ones are a bit dimmer – fine for where we put them, but I think I’ll just buy 13W lamps from now on. Like all CFLs, they take a moment to start and another couple of minutes before they reach full brightness.
Compared to the original 4x 50W lamps (totalling 260 Watts including transformer losses), the 4x 11W CFL downlights (totalling 44 Watts) use only 17% of the electricity. I can live with a few minor drawbacks for that kind of savings!
I’m hoping that one day in the not-too-distant future I’ll be able to buy LED lamps for the GU10 fittings at a reasonable price and save even more energy. But until then, the CFL downlights are a workable solution.
It’ll be interesting to see what effect these 10 lights will have on our electricity usage.
Note: CFL downlights contain mercury, a toxic substance – if you install them, make sure you know the procedure to safely clean up a broken CFL.