Smart meters and energy monitors explained

Knowing exactly how much energy you're using — in real time, in pounds or euros or dollars — changes how you think about it. A smart meter or energy monitor is the tool that makes that visible. The savings, though, come from what you do next.

What a smart meter is

A smart meter replaces your existing gas and electricity meters with a newer model that records your consumption and automatically sends the readings to your energy supplier — usually every 30 minutes, though settings vary. You no longer have to submit manual meter readings, and your bills are based on actual rather than estimated consumption.

Smart meters also communicate with an in-home display (IHD) — a small screen, usually placed somewhere visible like the kitchen counter, that shows your energy use and estimated cost in near-real time. This is the part that's actually useful for changing behaviour.

Smart meter rollouts are progressing across much of Europe, the UK, North America and beyond, but availability and how they work varies by country and supplier. In most places you request one through your supplier; it's typically installed free of charge by a trained engineer.

The in-home display: why it helps

Research consistently shows that having visible feedback on energy use changes behaviour — people who actively use their display tend to use less energy than those who ignore it. The IHD makes the abstract concept of kilowatt-hours tangible by showing cost in your currency, often updating every few seconds.

What you can typically see on an IHD:

• Current power draw — how many watts or kilowatts your home is using right now, and the equivalent cost per hour.
• Today's total — how much energy and money you've used since midnight.
• Weekly and monthly history — so you can see trends and compare periods.
• Gas and electricity — many homes have both; a good IHD shows both separately.

The insight this gives you is real. When you switch on an appliance and watch the number jump, you understand its cost in a way that an annual bill never conveys. For more on how to use this to cut standby power and identify energy-hungry devices, see also our home energy audit guide.

Smart meter vs. a plug-in energy monitor

You don't necessarily need a smart meter to get energy visibility. There are two common types of cheaper, DIY energy monitors:

• Clip-on whole-home electricity monitors — a sensor clamps around the main electricity cable at your meter or consumer unit and transmits data wirelessly to a display. Setup takes about 10 minutes, no engineer needed, and they cost relatively little. They show whole-home electricity use in real time, similar to an IHD. They don't automatically send readings to your supplier, and most don't cover gas.
• Plug-in power meters — small devices that sit between an appliance's plug and the socket, measuring how much electricity that specific appliance uses. Excellent for testing individual devices: kettles, televisions, fridge-freezers, gaming consoles on standby. Cost is typically very low.

If you don't yet have a smart meter and want to understand your usage, a clip-on monitor or a set of plug-in meters is a perfectly good starting point. The smart meter adds automatic billing and data sharing with your supplier, but the energy insight they provide is comparable.

Smart meters and time-of-use tariffs

A smart meter is a prerequisite for time-of-use electricity tariffs — deals where the price of electricity varies by time of day, with cheap overnight rates and more expensive peak-hour rates. Because a smart meter records exactly when you use electricity (not just how much), your supplier can bill you accurately at different rates for different periods.

This opens up real savings for households that can shift flexible loads — running the dishwasher or washing machine overnight, charging an electric car off-peak, or using a home battery charged at the cheap rate. Without a smart meter, these tariffs aren't available.

Honest limits

• A smart meter by itself saves nothing. The meter is a measurement tool, not an efficiency device. Savings only materialise when you act on the information it provides — changing habits, eliminating standby waste, adjusting thermostat settings and so on.
• Not all in-home displays are equally useful. The quality of the IHD varies considerably between suppliers and meter generations. Some show cost clearly; others show only kilowatt-hours that are harder to interpret. If yours is hard to read, your supplier may be able to offer an alternative app or data view.
• Data and privacy. Smart meters send half-hourly consumption data to your supplier. This data, in aggregate, can reveal a lot about your household's activity patterns. Most countries have data protection rules governing how it can be used, but it's worth checking your supplier's privacy policy. In many places you can opt to send readings less frequently (daily or monthly) while still getting automated billing, at the cost of losing real-time tariff features.
• Signal and compatibility issues. Smart meters communicate via a dedicated radio network. Coverage gaps exist in some areas, particularly in basements or rural locations. Ask your supplier before installation if coverage is a concern.

Getting a smart meter

In most countries with active rollout programmes, smart meters are offered free by your energy supplier — the cost is recovered through your energy bills collectively, not charged individually. Contact your supplier to request one; waiting times vary.

Installation is done by a trained engineer, takes roughly an hour, and involves a short period with no electricity or gas supply. You should not need to do anything yourself. After installation, the engineer should explain how the IHD works and how to read it.

If you switch suppliers after getting a smart meter, check whether the new supplier can operate your meter in "smart mode" — some older generation meters (called SMETS1 in the UK) may revert to "dumb mode" temporarily with a new supplier, though most countries are resolving this.

How to do an energy-spotting session with your display

1. Pick a quiet time. Choose a moment when no one is cooking or using major appliances — early morning or mid-afternoon works well.
2. Note your baseline. Look at the current power draw on the display with everything you think is off. What's the reading? This is your standby load — the power your home uses continuously even when you think it's idle. A high standby figure (more than 50–100W for a typical home) indicates significant waste worth investigating.
3. Test appliances one at a time. Switch things on or off one at a time and watch how the display figure changes. Note the biggest contributors — a tumble dryer, electric shower, or immersion heater will spike the reading dramatically; a phone charger barely moves it.
4. Find the standby offenders. With appliances switched off at the wall (not just on standby), note how the baseline drops. Devices left on standby — TVs, set-top boxes, games consoles, smart speakers — can collectively add meaningful waste.
5. Check peak-usage periods. Look at your weekly history on the display. When are your highest-consumption periods? Often it's the morning rush and early evening. Understanding this helps you decide whether a time-of-use tariff could save you money by shifting loads.
6. Write down your targets. Make a short list of the three to five biggest users you've spotted and decide what to do about each. Then check in again next week to see whether the baseline has improved.

Checklist for making the most of your meter

• Place the in-home display somewhere you actually look — kitchen counter or hallway.
• Do an energy-spotting session to find your standby baseline and biggest appliance loads.
• Fix any standby waste you find — switched power strips are the easiest solution.
• Check your weekly history to spot high-consumption periods and investigate what drives them.
• Ask your supplier about time-of-use tariffs if you can shift loads to off-peak times.
• Review your supplier's privacy settings for how frequently data is shared.
• If your display is hard to read or has stopped syncing, contact your supplier for a replacement or app alternative.
• Use a plug-in power meter to test specific appliances the whole-home display can't isolate.