Why This Matters to You
If your house still has halogen downlights, you're paying to heat your ceiling. A halogen converts most of the energy it draws into heat rather than light, and in a house with twenty of them the running cost adds up to real money every year.
Below are the numbers, with the assumptions stated so you can adjust them to your own house, plus the part most articles skip: what a proper LED upgrade actually involves, and where the cheap version goes wrong.
What Halogens Actually Cost You
A standard halogen downlight draws around 50 watts. An equivalent LED does the same job on roughly 8 watts. That's about 42 watts saved per fitting.
Working it through, and being clear these are assumptions rather than a quote: twenty downlights, averaging four hours a day across the house, at 45 cents per kilowatt hour, which is in the range South Australian households have been paying.
That's 840 watts saved when they're all running, about 3.4 kilowatt hours a day, and roughly 1,200 kilowatt hours across a year. At 45 cents, somewhere near 550 dollars a year.
Your house will differ. Fewer lights, or fewer hours, and the figure comes down accordingly. But the shape of it holds: on a full house of halogens the saving is usually in the hundreds per year rather than the tens, and South Australian electricity prices make the case stronger here than in most of the country.
They Last Long Enough to Matter
Halogen globes typically give 1,000 to 2,000 hours. A decent LED fitting is rated for 25,000 hours or more. On the four hours a day above, that's a globe change every year or so versus something that should outlast the next fifteen.
The practical benefit isn't really the cost of globes. It's never having to get the ladder out, work out which of the three fittings above the stairwell has gone this time, and find that the replacement is a slightly different colour to the rest.
The Safety Case Is Stronger Than the Savings Case
Halogen downlights run extremely hot, up to around 300 degrees at the fitting. That heat sits in your roof space, directly against whatever is up there. Older installations frequently have insulation pushed against fittings that were never designed to tolerate it, and insulation in contact with a halogen is a genuine fire risk.
It's also why you sometimes find a neat square of missing insulation around each downlight in an older house, which is doing exactly what it should for fire safety while quietly undermining the thermal performance you paid for.
LEDs run cool enough that appropriately rated fittings can be covered by insulation, so you get the full benefit of the insulation and lose the hot spots. In an Adelaide summer that's worth something beyond the lighting bill.
Light Quality, and Choosing a Colour Temperature
Modern LEDs come in a range of colour temperatures, and this is the choice people most often get wrong, because it's made on a shelf under fluorescent lighting rather than in the room.
Warm white, around 3000K, is closest to the halogen look people are used to, and suits bedrooms and living areas. Cool white, around 4000K, is cleaner and works well in kitchens, laundries and bathrooms. Daylight, 5000K and above, is bright and clinical, and in a home it usually reads as harsh outside of a garage or workshop.
Mixing temperatures across an open plan area is the other common mistake. If the kitchen and living room see each other, they should match. Many current fittings are switchable across all three, which takes the risk out of the decision, and it's worth asking for those.
Colour rendering matters too, particularly in kitchens and bathrooms. A poor LED makes food and skin tones look wrong in a way that's hard to name but easy to notice.
What a Proper Upgrade Involves
Swapping a halogen for an LED isn't always just changing the globe. Depending on what you have, the job may involve removing old transformers, which continue drawing power and are a common failure point, replacing the whole fitting rather than the lamp, and checking that the existing cabling and the way the fittings were installed is sound.
Older downlight installs are also a reasonable place to find work that was done poorly. Once the fittings are out and we can see into the ceiling, problems that were invisible from below tend to surface.
If you're changing the number or position of fittings rather than swapping like for like, that's a lighting design question as much as an electrical one, and it's worth getting right while the ceiling is open. Our downlight installation page covers the layout side, and feature lighting and LED strip covers the work that goes beyond general lighting.
Where the Cheap Version Goes Wrong
The failure modes with budget LED fittings are predictable. Flicker, which some people see and some don't, and which is genuinely unpleasant if you're one of the people who does. Buzzing on dimmers, because the dimmer was designed for a resistive halogen load and an LED isn't one. Colour drift, where fittings that matched on day one no longer match after two years. And early driver failure, where the LED chip is fine but the electronics behind it aren't, at which point you're replacing the fitting anyway.
If you're dimming, the dimmer and the fitting need to be a compatible pair. That's the single most common reason a new LED install disappoints, and it's entirely avoidable by choosing them together.
The Short Version
On a full house of halogens the energy saving usually pays for the upgrade within a few years, the fire risk in the roof space goes away, and the maintenance stops. The savings make it sensible. The heat is the reason not to put it off.
