Smart Heating: Are Smart Thermostats Really Worth It?
For many households, heating costs are one of the biggest expenses of the year, and at the same time radiators often run at full power when nobody is at home. This is exactly where smart thermostats come in. But are smart thermostats really worth it, or are they mainly a convenient toy for technology fans? The answer depends heavily on how you live, what your daily routine looks like and how well your heating system is already set up.
In this guide, you will find out what smart thermostats do differently from conventional thermostatic heads, how much saving is realistic and for whom the purchase pays off. We also show which technical requirements apply, how to set the devices up sensibly and which obligations and funding options exist in 2026 for room temperature control.
What smart thermostats do differently from conventional thermostatic heads
A conventional thermostatic head works purely mechanically: an expansion element reacts to the room temperature and opens or closes the valve. It therefore maintains a set temperature but knows nothing about your daily life. Whether you leave the house at seven in the morning or only come home late in the evening makes no difference to it. We explain in detail how to understand the numbers on the dial in the guide Setting Your Thermostat Correctly.
A smart thermostat replaces this head with an electronic actuator with a temperature sensor. It can be operated via an app, a hub or voice control and works according to time schedules. Many models detect an open window from the rapid drop in temperature and close the valve until airing is finished. Some systems also use your smartphone's location to turn up the heating before you return. The decisive difference is therefore not the technology itself, but the ability to provide heat specifically only when it is needed.
How much can you really save with smart thermostats?
Manufacturers often advertise high savings rates. However, these figures usually arise under favourable conditions, for example compared with a flat that was previously heated all day. Independent assessments are more cautious: Consumer advocates expect electronic thermostats to save up to around ten per cent of heating energy. How much of this you actually achieve depends above all on how big the difference is between your previous heating behaviour and a well-tuned time schedule.
If you already consistently turn down the thermostats when you leave the house, you will hardly save any more. If, on the other hand, you heat empty rooms during the day or regularly forget to turn the heating down, you will benefit considerably more. The following overview will help you assess this:
| Situation | Benefit of smart thermostats |
|---|---|
| Working people who are regularly out during the day | high, because time schedules reliably lower the temperature during empty hours |
| Changing working hours or working from home on some days | medium to high, app control compensates for deviations |
| Rarely used rooms such as guest rooms or hobby rooms | high, these rooms are only heated when needed |
| Flat occupied all day with a constant daily routine | low, the effect is limited to the night-time setback |
| Underfloor heating or heat pump with a low flow temperature | rather low, sluggish systems react slowly to short setbacks |
Who smart thermostats are worth it for, and who hardly benefits
The purchase costs consist of the individual radiator thermostats and, for many systems, a hub that connects the devices to the home network. The more rooms you equip, the more important the question of payback becomes. The calculation works out well in flats and houses with pronounced periods of absence and several rooms that are only used for a few hours. Time schedules are also particularly effective in older buildings with radiators that respond quickly to changes.
The investment is less worthwhile in well-insulated new buildings with surface heating. There, the screed and heating surfaces react so sluggishly that short setbacks save hardly any energy and reheating partly cancels out the effect. Here, a well-adjusted heating curve and a low flow temperature usually achieve more than individual smart thermostats. For tenants: most models can be fitted without tools and swapped back for the old heads when moving out.
Requirements: valve, heating system and wireless standard
Before you buy, it is worth taking a look at the existing valve. Most radiator valves in Germany have the standard M30 x 1.5 connection. Adapters are available for valves from other manufacturers and are often already included in the scope of delivery. With very old or stiff valves, it can make sense to have the valve insert checked by a specialist company beforehand so that the actuator works properly.
With underfloor heating, smart room thermostats on the wall are used instead of radiator thermostats; they control the individual circuits via actuators on the heating circuit manifold. Also pay attention to the wireless standard: systems that support open standards such as Matter are easier to combine with devices from other manufacturers. Data protection and reliability are also important. Check whether the thermostats can still be operated locally if the internet fails and which data is transferred to the manufacturer's cloud. Battery-powered devices also need new batteries regularly; the stated battery life is a good comparison criterion.
Setting up smart thermostats correctly
The best technology saves nothing if the time schedules do not suit your daily life. Set separate times for each room and lower the temperature moderately during periods of absence, for example by a few degrees. Letting rooms cool down completely does not make sense, because walls and furniture then have to be warmed up again with considerable effort and the risk of mould increases in cool corners. Bedrooms may be cooler than living rooms, and bathrooms benefit from short warm phases in the morning and evening.
The basic setting of the heating system is just as important. Hydraulic balancing ensures that each radiator receives the right amount of water. Only then can smart thermostats regulate evenly and quietly. After setup, check the history data in the app during the first few weeks: it shows whether rooms warm up in time or whether the preheating times should be adjusted.
Obligations and funding: what applies in 2026?
Section 63 of the German Building Energy Act (GEG) requires heating systems using water as the heat transfer medium to be equipped with an automatic device for controlling the room temperature room by room. Conventional thermostatic valves already meet this requirement. If such a control is missing, the owner must retrofit it. Exceptions apply, among others, to underfloor heating in rooms with less than six square metres of usable floor space. Smart thermostats are therefore not mandatory; they are a more convenient form of the prescribed room control.
As a rule, there is no dedicated funding for buying individual smart thermostats. If they are installed as part of a more comprehensive heating optimisation, for example together with hydraulic balancing by a specialist company, funding via the Federal Funding for Efficient Buildings (BEG) may be possible. The guideline was amended in July 2026. Before commissioning the work, you should therefore check the current conditions with the BAFA and submit your application in good time before work begins.
Frequently asked questions
Are smart thermostats worth it in a rented flat?
Yes, if you are regularly away from home or rarely use certain rooms. Most models can be fitted without tools and removed again when you move out. Keep the old thermostatic heads safe for this purpose.
How much heating energy do smart thermostats save?
Consumer advocates expect up to around ten per cent. The actual figure depends heavily on your previous heating behaviour, the building's insulation and the heating system.
Do smart thermostats work with a heat pump?
Yes, although the benefit is usually smaller. Heat pumps work most efficiently with constant, low temperatures. Large setbacks can cause the system to operate unfavourably when reheating. Moderate schedules are the better choice here.
Do I need a specialist company for smart thermostats?
As a rule, not for fitting them to standard valves. With underfloor heating, old valves or in combination with hydraulic balancing, however, a specialist company makes sense.
Conclusion
Smart thermostats are worthwhile above all where rooms are empty at times and have previously simply been heated continuously. A saving of up to around ten per cent is realistic, and often considerably less in well-insulated houses with surface heating. You will achieve the greatest effect if the time schedules suit your daily life and the heating system is hydraulically balanced. Before buying, check the valve connection, wireless standard and data protection so that the system works reliably in the long term. You will find controllers and components for your heating system in our Heating & Solar, Solar Controllers and Heat Pumps categories.
