UK energy prices remain significantly higher than pre-2022 levels, and for most households, heating and standby power are the two biggest areas of waste. Smart home technology can make a meaningful dent in both — not through gimmicks, but through better scheduling, presence awareness, and real-time visibility into what’s actually using energy. This guide covers what actually works and what the realistic savings look like.
Where Your Energy Actually Goes
Before spending money on smart home kit, it’s worth understanding where UK household energy goes. According to the Energy Saving Trust, a typical UK home spends energy roughly as follows:
| Category | Approx % of energy bill |
|---|---|
| Space heating | 61% |
| Water heating | 18% |
| Appliances and lighting | 13% |
| Cooking | 5% |
| Other | 3% |
The implication is clear: heating is where the money is. Smart home investments that reduce heating waste will have a far greater impact than turning off standby lights. That said, both are worth addressing.
1. Smart Thermostat: The Highest-Impact Upgrade
A smart thermostat is the single most impactful smart home purchase for reducing energy bills. The key mechanisms:
Geofencing and auto-away
Conventional thermostats heat your home to a schedule. If you leave early or come home late, you’re either heating an empty house or coming home to a cold one. A smart thermostat with geofencing — Tado is the best UK example — uses your phone’s location to detect when you leave and automatically drops the temperature. When you’re heading back, it starts heating in time for your arrival. Tado claims average savings of 31%; independent testing suggests 15–25% is realistic for most UK households. At current gas prices, that’s potentially £150–£300/year.
OpenTherm boiler modulation
Standard thermostats switch your boiler fully on until the target temperature is reached, then fully off. Thermostats that support OpenTherm (Tado and Nest both do) can communicate directly with a compatible boiler and modulate its output — running at lower temperatures for longer rather than full blast. This is more efficient, particularly for homes with good insulation, and can reduce gas consumption meaningfully over a heating season.
Room-by-room control
Smart thermostatic radiator valves (TRVs) — available from Tado, Drayton Wiser, and others — let you set different temperatures in different rooms and only heat rooms that are actually occupied. Stopping the heating in the spare bedroom or home office when nobody’s in them adds up significantly over a winter.
The Tado Smart Thermostat X (around £119) is our recommended starting point. See our full smart thermostat guide for a full comparison.
2. Smart Energy Monitor: Know What’s Costing You
Before you can reduce energy waste, you need to know what’s causing it. A smart energy monitor clips onto your electricity meter and gives you real-time and historical data on your whole-home electricity consumption — by appliance if you use smart plugs alongside it.
Hildebrand Glow
If you have a smart meter (most UK homes now do), the Hildebrand Glow (around £35) is the best option. It reads your smart meter data directly via your in-home display signal and feeds consumption data into their app and into Home Assistant via an integration. No clip-on sensor needed. The data includes both gas and electricity in real time, down to 10-second intervals.
Sense Energy Monitor
For homes without a smart meter, the Sense Energy Monitor clips onto your consumer unit (fuse box) and uses machine learning to identify individual appliances from their electrical signatures. It’s more expensive (around £250) and requires installation near the consumer unit, but the appliance-level breakdown is genuinely illuminating — most people are surprised by what they discover.
3. Smart Plugs with Energy Monitoring: Kill Standby Waste
Standby power is a smaller part of the energy bill than heating, but it’s also the easiest to address. UK households leave an average of £65/year in standby power running, according to Energy Saving Trust estimates. Smart plugs with energy monitoring let you see exactly what each device consumes and schedule them off when not in use.
The TP-Link Tapo P110 (around £16) is the best budget option with energy monitoring. Identify your biggest standby offenders — typically older televisions, gaming consoles, and desktop computers — and schedule them off overnight or when you’re at work.
A practical tip: plug your TV entertainment system (TV, soundbar, console, streaming stick) into a single smart plug. When you turn the TV off via the smart plug, everything on that circuit cuts power completely rather than sitting on standby. This is one of the highest-impact single-plug uses.
4. Octopus Agile: The Smart Home Energy Tariff
If you’re on a variable electricity tariff like Octopus Agile, the smart home opportunity goes much further. Agile prices electricity by the half-hour based on wholesale market rates — typically cheapest between midnight and 6am, and most expensive during weekday evenings (4–7pm). Prices occasionally go negative, meaning you get paid to use electricity.
Home Assistant’s Octopus Energy integration exposes real-time Agile prices and allows automations based on them. Practical examples:
- Run the dishwasher and washing machine only during cheap-rate periods
- Charge an EV overnight when prices are lowest
- Boost your hot water cylinder during negative-price periods
- Delay electric heaters until the cheap-rate window opens
UK households with EVs or heat pumps report saving £300–£600/year on Agile versus a standard flat tariff, with Home Assistant automations handling the scheduling entirely. For gas-heating households without an EV, the savings are smaller but still meaningful — typically £50–£150/year on the electricity bill.
5. Smart Lighting: Smaller Impact, Still Worth Doing
Switching to LED smart bulbs saves energy versus incandescent or halogen bulbs — a 60W halogen replaced by a 9W LED equivalent saves around £8–12/year per bulb at current UK electricity prices. The smart element adds scheduling (lights off when you leave) and motion activation (lights only on when a room is occupied), which can add a further 20–30% reduction in lighting energy.
The honest note: lighting is typically only 10–15% of a household electricity bill, and electricity is a smaller part of the total energy bill than gas. The savings from smart lighting are real but modest — don’t expect smart bulbs to transform your energy bill the way a smart thermostat can.
Realistic Savings Summary
| Upgrade | Estimated UK Annual Saving | Typical Cost |
|---|---|---|
| Smart thermostat with geofencing | £150–£300 | £120–£220 |
| Smart TRVs (whole home) | £80–£150 | £200–£400 |
| Smart plugs (standby elimination) | £30–£80 | £50–£100 |
| Smart energy monitor | £50–£150 (behaviour change) | £35–£250 |
| Octopus Agile + HA automation | £50–£600 (depends on usage) | £0 (tariff switch) |
| LED smart bulbs (replacing halogen) | £40–£100 | £100–£300 |
A realistic whole-home smart energy setup — smart thermostat, a few TRVs, and smart plugs on your biggest standby offenders — typically pays for itself within 18–24 months at current UK energy prices. After that, the savings are ongoing.
Where to Start
If you’re only going to do one thing, do the smart thermostat. It’s the highest-impact upgrade by a significant margin. If you have a smart meter, add the Hildebrand Glow to understand your baseline. Then work through smart plugs on your biggest standby devices. Everything else is incremental improvement on that foundation.