We all know the obvious power hogs like plug-in electric heaters, but what about the less obvious ones? Do mobile phone or ipod chargers really save you much if you unplug them?

Our tables show typical running costs for a range of appliances - bathroom, kitchen and laundry; heating, cooling and lights; and general household appliances - so you can see where the dollars go. There are also ways you can make changes to knock back the bill:

Plasma TVs

Maybe you like to have a TV music channel playing in the background when you’re home. If it’s a plasma TV, it could be costing you more than five times as much as playing a CD on the stereo. Plasma TVs are an example of products that cost more to run than the technology they replaced. Other products, like the newest fridges, cost less.

Here’s a surprise: A 42” plasma screen, watched an average of five hours a day, could cost $181/year - $70 more per year than a new medium-sized fridge running all day. Playing games on a Playstation3 through the plasma five hours a day adds another $79 - total cost $260! Nintendo Wii on a 32” LCD, by comparison, costs $60.

Appliances on standby

There are appliances you aren’t supposed to turn off – like the DVD recorder or VCR. If you switch them off at the wall, your timer settings are lost and it can be a hassle to re-set them. Fortunately DVD recorders use next to nothing on standby.

Set-top boxes or decoders are nowhere near as efficient. Sky says you shouldn’t turn off your set-top box as it needs to be updated regularly. We wish Sky could design a low-power standby mode like Energy Star TVs. A set-top box can cost $43/year to run, while an energy-efficient TV on standby costs less than $2.

Chargers

We’re often told to unplug those mobile phone and ipod chargers. But the new-generation chargers use so little it’s barely worth the bother. It’s less than a cent a week – though for safety reasons you should unplug.

Tip: Feel the charger or appliance after it’s been plugged in a while. If it’s warm, you’ll save money if you unplug it.

Hot water

Hot water is a big power consumer. A 10-minute shower costs around half the price of a deep soak in the bath. A five-minute shower is even better. But you should have a water-efficient shower head, or it won’t be as cheap.

If you hand-wash dishes then rinse them in hot water, we estimate it’s costing 28c (a 15-litre sink filled twice). To wash and rinse the number of dishes you can load into a modern dishwasher, we think at least two lots of wash and rinse water are needed. A good dishwasher can do the job for half the cost – as long as you don’t run it half full.

Tip: avoid the half-load setting – it usually costs almost as much as a full load.

Most of us already cold-wash clothes, but we’ve done the sums to show how much it costs using warm water. In a large top loader, the hot water could cost more than that new super-concentrate detergent. If you use a dryer, add another 75  to 90c every time.