Know what a smart thermostat can and can't save before you buy one
Independent studies find little or no saving from smart or programmable thermostats over a well-used ordinary one; what saves energy is a lower setting, a night and away setback, and control per room.
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Manufacturers often promise savings of 25 to 40%, but those figures rest on unrealistic assumptions. A 2018 review of the research found moderate-quality evidence that smart thermostats do not save energy compared with standard thermostats, and a UK government review found little or no saving from programmable thermostats in practice, partly because most people rarely set a schedule. If you already turn the heating down at night and when you're out, a smart thermostat will add little, and comfort features can even raise your use.
What does save energy is how the heating is set. The Flemish government advises a digital thermostat with at least two programs: turn it down to 14 to 16 °C an hour before bed and when the house is empty during the day. Thermostatic radiator valves let you control each room separately and pay for themselves in under two years. Zone control per room can save energy when it is set up properly.
A smart thermostat can still be worth it if it gets you to use a schedule you otherwise wouldn't, or if you want remote control. In a poorly insulated home, insulation will save far more.
Details
| Impact | Indirect · This saves no energy by itself: it is a rule, a service, a contract, or a health or safety item. How we rate impact |
|---|---|
| Estimated saving | A 2018 review of the evidence found that smart thermostats do not save energy compared with standard ones; savings come from how you set the heating. (confidence: medium) |
| Who acts | You and your landlord |
| Needs landlord's agreement | No |
| Type | Rules explained |
| Constant or subject to change | Constant · Good practice that barely changes with new laws, prices or services. |
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Sources
- Verwarmingstips (in Dutch) · Vlaamse overheid (vlaanderen.be) (official source) · checked on
- Do domestic heating controls save energy? A review of the evidence · Lomas et al., Renewable and Sustainable Energy Reviews 93 (2018) (research) · checked on
- Heating Controls: International Evidence Base · UK Department for Business, Energy and Industrial Strategy (2017) (research) · checked on
- Hoe bespaar je energie met een slimme thermostaat of radiatorknop? (in Dutch) · Testaankoop (consumer organisation) · checked on