Trick of the lights

G Magazine

When did changing a light bulb get so complicated? G sheds some light on the subject.


Top to bottom: CFL, Halogen, LED.

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It may be a classic (even clichéd) green gesture, but changing a light bulb remains one of the easiest eco actions we can take. Yet, we’re still not bright sparks when it comes to green lighting. The Federal Government estimates most homes could reduce their lighting energy needs by at least 50 per cent, simply by getting lighting savvy.

Perhaps they haven’t walked into a hardware store lately. Choosing the right eco lighting sometimes feels like an exercise in mental gymnastics as you count Kelvins, compare eco options and convert wattages. Hardly fodder for feeling smart.

Given that confusion over eco lighting options remains, we thought we’d shed some light (bad pun!) on the situation.

Watt makes lighting eco?

Lighting uses about seven per cent of our total home energy use. The key to keeping things green starts with understanding wattage. The lower the watts (units of power), the less energy you’ll use. Easy? Yes. Except that the wattages used before 2009 (when most of the traditional pear-shaped incandescent light bulbs of your childhood were banned in Australia) don’t equate to wattages used in most common eco-lighting, Compact Fluorescent Lamps (CFLs). To convert a CFL’s wattage to the wattage of the past, times it by about 4.5. Annoying? Absolutely. But the new measurements aren’t going away so we suggest you recalibrate, lest you end up like your (much loved) mum, constantly converting metric to imperial.

Lighting choices explained

Understanding these three terms - CFLs, Halogens and LEDs (light-emitting diodes) – will allow you to talk lighting like a pro.


CFLs are currently the most common eco lighting used in Australian homes, although LEDs are expected to be the lighting of the future. Using only 25 per cent of the energy of an old-school light bulb, CFLs are now available in most shapes and sizes, and can last up to 20,000 hours. On the downside, they take a while to “warm up”, contain a wee bit of mercury and require you do some lighting design as you calculate how ‘warm’ or ‘cool’ you’d like your room (see below). For the technically minded, CFLs work by causing a phosphor coating on the inside of a glass tube to glow. For wordsmiths, the mechanics behind CFLs are the main reason why light bulbs are now ‘technically’ not known as bulbs, but lamps.


Those who like their lighting instant and dimmable will gravitate towards halogens. These incandescent lights use halogen gas and can last around 4000 hours. But be wary, halogen lighting (often called downlights) don’t have anywhere near the energy gains of CFLs. Part of the problem is that you need lots of them. If you want to spotlight a special painting or light a small target area (like a desk), halogens are mildly more efficient than old-style lightbulbs, but in terms of energy, you’d be better off seeing if you can substitute a CFL or LED specially designed for this purpose.


Given the futuristic moniker, it’s no surprise that Light Emitting Diodes (LEDs) are fast being recognised as the future of green lighting. These small light sources, which move electronics through a semiconductor, are already used widely in everything from mobile phones to traffic lights. To date cost has kept LEDs from being widely taken up in homes. Currently, you’ll pay far more for LEDs than CFLs, although prices are expected to tumble within the next year or two. Once they do (and when ever-tightening standards around lighting claims ensure claims LEDs last 100,000 hours can be verified) you’ll be able to pop an LED bulb directly into a standard light fitting.


For better or worse, modern lighting requires everyone to become an ‘in-home lighting designer’. This means you need to understand light colours, which are measured in Kelvins (K). Lower Kelvins led to ‘yellowish’ (or softer) light, while higher Kelvins mean the light is whiter or bluer. Clear as mud? Try this cheat sheet:
Going for a standard light bulb look? Go for 2700-3000K.
Lighting a kitchen or workspace? Ramp it up to 3500-4100K.
After that ‘blue sky at noon’ atmosphere? (aka: natural/daylight). Choose 5000-6500K.

To explore colour further, check out the interactive ‘Choose a light’ guide from the US Environmental Protection Agency. It lets you play with warm and cool lighting in a room. Super fun for all lighting-designers-in-training. www.drmediaserver.com/CFLGuide/index.html


Although new standards mean the CFLs widely used in homes can contain a maximum of 5 milligrams of mercury, there’s still the problem of what to do with them at the end of their lifecycle. Stick a CFL in the bin, and it’ll end up leaching mercury into the soil, so the obvious answer is recycling.

Unfortunately, this is harder than it sounds, because no-one quite knows how to deal with the mercury (except at scale). A recent government and industry push kicked off in June 2010 (http://flourocycle.com.au) encourages recycling of mercury-based lighting, but although it’s a good big picture initiative, it’s of little help to householders. Check www.environment.gov.au/settlements/waste/lamp-mercury.html for options in your state, or call your local council for their advice. for further CFL recycling info visit www.gmagazine.com.au.