No, they're not Twilight-themed appliances. 

However, like Edward Cullen, appliances left on stand-by are a big red flag. 

Working behind the scenes while you're sleeping, vampire appliances are consuming energy even when they're turned off. 

So what are they and will turning them off at the wall make any difference to your power bills? Let's find out.

What are vampire appliances?

These particular appliances enter a stand-by mode rather than fully powering down, meaning they continue to consume energy even while turned off. 

Essentially, it means you're paying for electricity that you're not even using. 

According to Canstar Blue's estimates, appliances on stand-by could cost you up to 10 per cent of your electricity bill: That's more than $100 annually. 

This depends on various factors, including the number of appliances left on stand-by, each appliance's efficiency rating and the rate you pay for electricity. 

Nevertheless, it's unnecessary power usage that's costing you more. 

Why do appliances use electricity on stand-by?

If an appliance has a remote control, LED light, touch-on button or similar function, then it uses stand-by electricity. 

Another way you can tell is if you can feel heat coming from an appliance that you aren't using, such as your laptop charger when it's not plugged into your laptop. 

Why do they do this? Because these devices constantly run background functions while on stand-by.

Wi-Fi checks, downloading content and continually having to prepare for remote, touch or voice activation all contribute to stand-by electricity usage. 

While the amount of electricity that feeds into most devices is minuscule, some devices may cost you more than others.

In 2021, Canstar Blue examined the stand-by costs of common household appliances. Its findings revealed some of the most expensive appliances and devices were:

• gaming consoles
• washing machines
• dishwashers

Should I switch off power at the wall?

Yes. The best way to save on stand-by costs is to make a habit of switching appliances and devices off at the power outlet when they're not in use.

Phones at 100 per cent battery still plugged into chargers, cordless vacuum cleaners sitting quietly in the corner, your Google Home patiently waiting for your daily "What's the weather today?" question — individually, these devices on stand-by draw a small amount of energy.

However, Choice's home products expert, Denis Gallagher, says that, if you've got more than a dozen appliances around the house, it's going to start adding up. 

"We've seen an average of 15 to 17 connected devices in the home in 2020."

"In just a few years time, that amount is going to double," he said.

And let's not forget the bigger cost: Choice says the stand-by energy used across Australia collectively amounts to tonnes of extra greenhouse gases in Earth's atmosphere.

Ultimately, it pays to shop around and check the star rating of appliances. 

What else can I do to reduce stand-by energy costs?

Check energy-efficient models

The Australian Energy Star Rating System is intended to indicate electricity usage running costs. However, it also provides a useful guide to stand-by costs. Essentially, the more energy efficient an appliance is, the less electricity it will use on stand-by.

Adjust your current stand-by settings

You can modify the settings on some smart televisions and smart consoles to minimise their stand-by functionality. You can do this to stop them from running background functions, such as scanning for Wi-Fi. 

Check your smart boards

Some electricity boards can detect when an appliance has entered stand-by mode and will cut its electricity feed entirely. It can also detect when you’re trying to turn the device back on and recommence its feed of electricity.