Heating & energy

Power use

Updated 08 Oct 2008

Introduction

Household energy can trickle away in ways we don't even think about. Tracking down some of the culprits could save you hundreds of dollars a year.

Where this energy goes has been extensively investigated by HEEP (Household Energy End-use Project). They monitored 400 houses over a 10-year period and identified some sneaky thieves of electricity.

New!

We've now tested 15 household electronic products to see how much energy each consumed - both when in use and "off".

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

Electronics use a surprising amount of power

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.

Electronics power use

We tested 15 household electronic products to reveal how much energy each consumes. Two tests were conducted on each device.

"Off"/standby: Turned on at the wall with the device itself "asleep": it's not active but the LED light (in most cases) is showing. This is what you achieve when you turn off a TV using a remote. We replicated it in our PC, iMac and laptop by shutting down the computer - and not turning off the master switch at the rear of the PC.
In use: The device switched on and in active use.

We then calculated how much energy (kWh) was being used and the cost at 18c per kWh (the average cost of electricity).

Guide to the table

Our test was conducted by the Australian consumer organisation Choice. Products were chosen to give an idea of their energy use. Other brands may produce different results. Note: The test did not include an LCD TV.

Mode

A - PC drive switched off and LED light not showing but master switch at the rear left on (also left on at wall).
B - cordless phone charges when on standby.
C - Nintendo Wii on standby with WiiConnect24 turned off.
D - Nintendo Wii on standby with WiiConnect24 turned on (WiiConnect24 is a feature that allows the Wii to receive messages and email while in standby mode).

Our house audit

In March 2007 we decided to do our own house audit - just to see where energy was being wasted in a typical household.

We focused not so much on the bigger items (such as hot water cylinders and space heating) but on the accumulation of small bits and pieces like appliances on standby. The list is surprisingly long.

Modern appliances are never actually "off".

Unless you turn them off at the wall, computers and monitors remain on - even if they hardly use any power. So do printers and scanners. Many run through a small transformer that's easy to plug in and forget. You may need to be cautious about this though, as some printers prefer being on standby rather than being physically switched on and off.

A computer with the monitor, scanner and printer can use up to 20W while apparently being off. Our household had two computer setups, so we start with 40W that could be saved.

Around the house?

TVs, DVD players, VCRs, stereos, game machines all use power on standby.

New models with an Energy Star label often use very little - down around 1W. Older models can use 15 to 25W. Our audit found three TVs, a decoder, a VCR, a DVD recorder, a Playstation, a home theatre amplifier, a CD player, and a cassette deck ... all humming away on standby.

All up, 74W. Just like leaving a light bulb on 24 hours a day. All except the decoder and VCR could be switched off at the wall. Even the VCR can, if you don't mind resetting the clock.

The decoder can also be switched off, although Sky prefers you to leave it going. It burns up a toasty 17 watts on standby. Most surprisingly, it only used another 0.4 of a watt when running. Not worth turning to standby! And is clearly a prime target for EECA's Energy Star.

You may not want to go to all this bother for the VCR and some of the stereo gear, but it does show the potential savings that can be made.

How about the kitchen?

We found a microwave clock, stove clock, cordless phone, a dustbuster, and four chargers - for the toothbrush, iPod, and mobile phone (plus a battery charger to feed the digital camera). This household has five mobile phones for four people.

(Mobile phone chargers are not always an energy thief. Of the phones in our CDMA test, none used more than 1 watt if left on without a phone connected. Some used nothing.)

If all these are left on, that's another 20W. The washing machine may also be on standby... not common, but possible. And then there's the doorbell - it has its own small transformer.

Out in the garage?

Is the cordless drill charger plugged in? Beer fridges can be real villains: they're often old and highly inefficient fridges retired to beer-cooling duty.

Standby waste

The potential standby waste in our house is 130W - that's two 60W light bulbs on all the time. This will cost you around $220 a year in electricity. Of course we use all these appliances, so the savings are a bit less in reality. Nonetheless, it shows the potential for savings if all appliances have the Energy Star.

Your own power meter?

You can check out your household energy use yourself by using a power meter. See our report on Power meters for more information.

Energy labelling

Energy labelling not only allows consumers to make better choices about energy-efficient products, it's also encouraged whitegoods' manufacturers to become more eco-friendly.

However, while star-rating energy labels are mandatory in New Zealand for selected whitegoods, they're not yet required for computing equipment.

An Australian report by ACNielsen last year found that 95 percent of the consumers it surveyed were in favour of a mandatory energy-labelling system being introduced for computing equipment.

Energy Star

This is an internationally recognised standard awarded only to the most energy efficient appliances. Energy Star can be identified by the symbol on the product's packaging.

This symbol may also be visible when you turn on your computer. Many of the world's leading manufacturers produce computers that are Energy Star compliant - including Compaq, Apple, Sony, IBM, HP and Toshiba.

TV sets currently qualify for Energy Star based on very low standby power use. In November 2008, the rules change, and only models which use 30% less energy when operating and have very low standby consumption will qualify.

We've been highlighting the most energy-efficient products for years. You can always check our tests and guides for confirmation.

Energy saving tips

Identifying the appliances that cost you the most is the first step. Next, think about what to do. You can reduce use by turning appliances off at the wall. You can also gradually switch to more efficient models. Energy-efficient light bulbs are an excellent and simple starting point.

Hot tips for energy saving

If your hot water cylinder is old and feels warm to the touch, buy it an insulating wrap.
Turn on heated towel rails only when they're needed.
Switch off the heat-drying part of the dishwasher cycle.
Check that your washing machine is set to cold washes.
Hunt down everything that is on standby and turn it off at the wall if you can - especially if it's warm to the touch.
Fit compact fluorescent bulbs in any room that's frequently used.
Get rid of the beer fridge, or use it only when really necessary.
When replacing appliances look for high "star ratings" or Energy Star labels.

Reducing electronics power use

Turn off when not in use: Put equipment like TVs, amplifiers, speakers, game consoles and DVD or CD players into standby mode when you're not using them. Better still, turn them off at the wall - as our table shows, some devices left on standby still consume a bit of power.
Enable energy-saving features: Enabling the power-management settings on your computer reduces energy use by putting your computer into a power-saving "sleep mode" after several minutes of inactivity. Both Windows and Mac offer easy to use power-saving features.
Upgrade your monitor: Bulky CRT monitors can consume more than twice as much power as LCDs. LCD monitors may be more costly up-front but can save you money in the long run. Reducing the brightness of your display also reduces energy usage.
Sell your old computer: Once your computer becomes obsolete, there are many alternatives to dumping it. Selling old computers on Trade Me can fetch good results, as obsolete hardware may be worth much more than you think. Whether they're working or not, computers and their parts can be of value to others - and can provide you with cash towards your next computer purchase.

Recycling is also becoming an option, with groups such as The Ark taking old computers off your hands. So you don't have to see them added to a landfill.
Video meetings: Using webcams to conduct virtual meetings instead of travelling to a meeting by car can help reduce fuel consumption. Videoconferencing is effective and simple to set up: it requires just a webcam, instant messaging software and a computer. Many notebook computers also include built-in webcams.

More information

Energy Star www.energystar.govt.nz
Energy calculator www.energywise.org.nz

More from consumer.org.nz

We list running costs (energy use) for most of the large appliances we test, including: