How much power do your appliances use?

How much power does my appliance use?

You’ll find a label on every appliance that tells you how much power it generates (in watts).

The most power an appliance with a regular three-pin plug can generate is 2400W (240 volts x 10 amps). One kilowatt (kW) is 1000 watts.

Your electricity bill shows how much energy you’ve used in kilowatt-hours (kWh). Therefore, an appliance rated at 2400W would use 2.4kW in an hour, and you’d be billed for 2.4kWh of electricity. On average in Aotearoa, 1kWh costs 25¢, so that appliance, running for an hour, cost 60¢.

You can calculate the energy used by an appliance (kWh) by multiplying its power in kilowatts by how many hours it’s in use.

For example, a kettle is rated at 2.4 kW. If it takes four minutes to boil, it uses 2.4 kW x (4 ÷ 60) hours = 0.16 kWh. That means it costs 4¢ (0.16kWh x 25¢) to boil a kettle. Rest assured, your tea addiction isn’t blowing your power bill through the roof!

Always-on appliances

Refrigeration

You probably aren’t going to replace your fridge-freezer just because a new one will cost less to run. But if you need to replace your old one, it pays to choose an energy-efficient model.

Choosing the most energy-efficient medium-sized (376-450L) fridge-freezer we’ve tested would save $119 every year compared with a similarly sized 15-year-old model. Even an averagely efficient new model would save you $85 each year.

If you’re running an old fridge or freezer in the garage, think hard about how much you need it. It could be sucking power at an alarming rate.

Router

A router quietly connects your home to the world at all hours of the day and night. It does this using just 7-8W of power – that’s an annual energy cost of $18.

Landline

If you’re still using a cordless landline, it isn’t likely to factor into any unexpectedly large power bills. The models we’ve tested cost no more than a couple of dollars every year.

Chargers

Charging mobile devices won’t blow your power bill through the roof. Charging a phone like the iPhone 14 from empty every day for a year costs about a dollar, while a tablet like an iPad Air, with a much larger battery, would cost no more than $3. And what about the habit of leaving chargers plugged in but not connected to a device? We measured the power use of a few typical chargers. None of the disconnected phone, tablet, laptop or generic USB chargers we tested generated more than 0.5W. The highest power use we found was a bike light charger that drew 1.9W.

Leaving disconnected chargers plugged in at the wall will use some energy – it’s not a lot, but it’s all a waste.

TIP: It’s easy to tell if your charger is a drain – if it feels warm, it’s using energy, so turn it off.

Cost of hot water

Hot water is a big power consumer. To minimise hot water heating make sure your cylinder and pipes are well insulated (you can fit an insulation jacket) so you’re heating water, not the air around it. But the easiest way to reduce the cost of hot water is to use less of it.

Baths and showers

Fit a water-efficient WELS 3-star rated shower head. A 10-minute shower using a 1-star shower head costs about $1.25. A 5-minute shower with a water-efficient 3-star shower head will cost just a third of that – 40c.

TIP: Time how long it takes to fill a bucket to the brim with your shower. If you can fill a bucket in less than a minute, you’ll save money by fitting a flow-reducing valve or replacing your showerhead with a low-flow model (look for a 3-star WELS rating).

If you like to soak in a bath, be aware that each one is likely to cost about a dollar.

Dish and clothes washing

If you handwash dishes then rinse them in hot water, we estimate it’s costing 30c (a 15-litre sink filled twice). To wash and rinse the number of dishes you can load into a dishwasher, you’ll need at least two lots of wash and rinse water. A good dishwasher can do the job for half the cost.

TIP: Avoid the half-load dishwasher setting – it can cost as much as a full load. Use an auto-sensing cycle and the dishwasher will adjust its energy and water use to suit the load.

Energy ratings

If you’re shopping for a new whiteware appliance, TV, computer monitor or heat pump, you’ll see an Energy Rating label prominently displayed on the products.

The label shows a simple star rating – the more stars, the more energy-efficient the appliance. The label also features an annual energy consumption (kWh per year), calculated from average expected use.

When comparing models of the same type – for example, small top-mount fridge-freezers – the one with the most stars will be the cheapest to run. But if you’re comparing two appliances of different size or type – for example, a small top-mount with a large French-door fridge-freezer – you can’t compare stars and need to use the kWh per year figure to find the cheapest to run.

Typical running costs

Our tables compare typical running costs for a range of appliances using the average electricity cost of 25c/kWh.

Bathroom

Heating

Kitchen

Lighting

Laundry

Entertainment