Smart Home Energy Savings: Which Controls Reduce Energy Use

• Smart thermostats — control when and to what temperature the heating runs. They can reduce heating when nobody is home or asleep. They cannot change insulation, heat loss or the efficiency of the boiler or heat pump. Potential depends on how the heating was controlled before. With a heat pump, large setbacks can sometimes increase energy use; follow the manufacturer's control guidance.
• Heating schedules and zoning — heat only the rooms in use, at the times they are used. Useful where parts of the home are empty for long periods; little effect in a small, fully occupied home.
• Smart plugs — switch a device fully off on a schedule or remotely. They only affect devices that would otherwise sit on standby or be left on; the plug itself draws a little power.
• Standby and load monitoring — shows what devices draw; it saves nothing until you act on what it shows.
• Smart lighting controls — occupancy sensors, schedules and dimming. The effect depends on how often lights are left on and on the lamps' wattage.
• Smart EV charging — shifts charging to cheaper or lower-carbon times. It usually changes when energy is used and what it costs, not how much the car needs.
• Smart hot-water controls — schedule water heating to demand and tariff. Effect depends on the system (cylinder, immersion, heat pump) and use pattern.
• Home energy monitors — show whole-home use in real time; useful for diagnosis, with no saving by themselves.

1. Find large energy loads — meter readings and appliance measurements; see the DIY home energy audit guide.
2. Identify controllable waste — energy used when nobody benefits from it.
3. Match a control to that waste — a control only helps with the waste it can reach.
4. Estimate the kWh affected — power × hours of waste removed.
5. Compare with device cost — kWh × your own price per kWh, against what the device costs.
6. Verify after installation — compare meter readings for comparable periods; for heating, account for weather.

The Standby Power Audit turns measured standby watts into kWh and cost, and the Home Energy Audit calculator estimates annual use per appliance. For heating, compare meter readings over similar weather, or use degree days, before concluding that a thermostat changed anything.

Smart charging moves the car's charging into a chosen window. The energy the car needs stays about the same; the cost and the emissions per kWh depend on the tariff and the grid at that time. To check whether a charging window is long enough for your driving, use the Home Charger Sizing Tool; the EV charging time and cost guide explains session cost.

They do not reduce heat loss through walls, windows or roofs, improve a boiler's or heat pump's efficiency, or make an appliance itself more efficient. Where waste is small, the saving is small, and the devices draw some standby power of their own. The Home Energy hub collects related tools; sources are on the methodology page.