Where does the energy go?

The HEEP study tells us we use most of our energy on space heating (34 percent) and hot water (29 percent). Solid fuel (56 percent) is the main way we heat our living spaces. But it also found energy trickling away elsewhere.

HEEP found the average house had a continuous electricity use of 112W. This is like leaving a 100W bulb lit up 24/7. If you've responded to the campaign to convert households to compact fluorescent bulbs (which we fully support) there go the savings from at least one bulb!

Appliances on standby

Half of this 112W was from appliances sitting around on standby. Heated towel rails and faulty fridges are other villains that need to be rounded up.

If you have a heated towel rail, you could try turning it on only when needed or adding a timer to regulate the "on" periods. It's harder to spot a faulty fridge. Seals gradually deteriorate, insulation fails over time, the refrigerant gas leaks out a little. The main clue is when the fridge runs most of the time; it should cycle on and off.

But wait ... there's more. If your fridge is over 10 years old, a new one will be far far more efficient. It's quite possible to save the price of a new fridge in running costs over the life of a new one.

Read more about appliance running costs here.

Household electronics

Just because computer and entertainment products are relatively small, don't assume they use less power. Many of them consume more power than a small family-sized refrigerator.

Our test of 15 electronics products found the most power-hungry device when in use was the plasma TV, followed closely by the PlayStation 3 and Xbox 360 (see Electronics power use for the full table).

The PlayStation 3 consumed more than 10 times as much power as the Nintendo Wii. That's incredible.

Leaving a PlayStation 3 and the plasma TV on all day, every day would cost $652 a year in electricity bills. This is almost 10 times as much as it would take to run a small fridge-freezer for a year.

The 42" plasma TV consumed five times more power than a traditional 29" CRT TV and almost three times as much as a large fridge freezer.

The average desktop PC also used lots of power. Interestingly, its Apple equivalent the iMac (an all-in-one computer that includes a built-in display) consumed less than half as much power as the Windows-based PC plus an LCD computer monitor. The LCD monitor was far more energy efficient than a CRT, using less than half the power.

Just having a PC, its LCD monitor, a wireless modem, a plasma TV and a DVD player in use for 24 hours every day costs $605 a year. Shutting down the PC and leaving all the other devices on standby would cost around $20 for the same period - not to mention the savings in energy use.

For comparisons, we used fridge-freezers from Fisher & Paykel. From our tests a small (250 litre) model costs $67 per year to run, and a 520 litre model just $116.