Author: Darren
• Monday, May 25th, 2009
After some discussion on power-hungry low-voltage halogen downlights in the comments section of my We Now Have Solar Power post, I thought it was high time I did something about them.
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 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). 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 kits, 6x 11W lamps and 4x 13W lamps"
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