Mandatory from 2030: Smart heating thermostats could become quite expensive for households.

What begins as a climate-protection idea could end up as an expensive forced purchase for many people.

Tighter control of heating, lower energy use, less CO₂ - that is the political promise. Yet the plan to make connected thermostats mandatory in every room raises a question that matters far more to many homeowners and tenants: who pays for it all - and does the investment actually pay off?

Mandatory smart thermostats: what the requirement is really about

France has already set out a clear direction: by 2030, a very large number of flats must have connected thermostats fitted to every radiator. Similar debates are under way in Germany too - driven by climate targets, rising energy prices and a push for better control of consumption.

The political logic sounds straightforward at first: if every heat source can be controlled individually and digitally, residents can set temperatures room by room, adjust heating schedules, analyse usage data and reduce energy consumption. Traditional twist thermostats respond slowly and offer little transparency; smart models are sold as a route to higher efficiency.

"The idea: set precisely, room by room, when and how much to heat - and cut heating bills over the long term."

Using an app, a wireless hub or a smart-home system, residents can, for example:

• set a separate temperature for each room,
• tailor heating times to their daily routine,
• turn the heating down while out,
• analyse consumption data and identify "energy-guzzling rooms".

Governments point to exactly this added value to justify a requirement. The argument is that savings driven by behaviour are cheaper than subsidising insulation or new heating systems everywhere.

The unpleasant downside: subsidies disappear, but the bill remains

France also shows how quickly a sensible-sounding measure can turn into a cost trap. The state initially planned to subsidise the purchase and installation of connected thermostats. After major fraud cases, the government withdrew that support again.

That leaves households to cover the full cost - and it can be substantial:

Number of radiators	Average cost per thermostat	Total cost per flat
2	around 300 euros	around 600 euros
4	around 300 euros	around 1,200 euros
6	around 300 euros	around 1,800 euros

For a typical flat with four radiators, the bill comes to roughly 1,200 euros. In larger flats or houses with more radiators, the total quickly rises to levels that are hard to manage, especially for households on tighter budgets.

Who would be exempt - and who would not

The French rules include certain exemptions that could serve as a template elsewhere. No requirement applies there to:

• buildings heated mainly with a wood-burning stove,
• situations where the investment is not expected to pay for itself within ten years.

The aim is to avoid forcing people to change heating controls where there is little technical potential to save energy, or where the system is rarely used. Even so, for most households with standard radiators and central heating, the obligation would still apply.

"Anyone using normal radiators and a central heating system will, in many cases, not be able to argue their way out of the requirement."

Political backlash: "regulatory frenzy" and interference in everyday life

Opposition to a mandate is coming not only from consumer advocates, but also from economists and politicians. Critics describe it as a "regulatory frenzy" and warn that the state is increasingly dictating how private homes are arranged - from the type of heating system right down to the thermostat on each individual radiator.

What is especially contentious is that the state sets requirements while increasingly stepping back from the costs. Grant schemes are being cut back, yet obligations remain in place - or are even tightened. Many people feel they are being left to deal with the consequences alone.

Regulatory costs keep piling up for homeowners and tenants

A smart-thermostat requirement would not arrive in isolation. Already, expensive building and energy rules are stacking up - from insulation standards and new heating rules to refurbishment obligations. In France, many residential developments must, for instance, produce a so-called multi-year plan for upcoming modernisation work. Comparable debates are taking place in Germany in connection with the Building Energy Act and wider climate requirements.

For owners, that can mean one thing: no sooner is one renovation finished than the next rule appears. In the end, the costs land either directly with the owner or indirectly with tenants through higher service charges and rents.

• smart thermostats
• insulation measures
• replacing heating systems
• mandatory surveys and energy performance certificates
• modernisation surcharges in rented buildings

Consumer organisations warn that this accumulation of individual measures puts particular strain on middle- and lower-income households. Often, the only options are to take on debt or postpone essential repairs in order to fund new obligations.

Do the devices really save as much as promised?

On paper, the calculation sounds appealing: estimates suggest that heating rooms according to actual need can cut energy use by 10 to 30 per cent. In practice, however, the outcome depends heavily on the starting point.

Key factors that determine the real-world savings include:

• Were people already heating carefully, or were radiators previously left running at full blast?
• Is the home well insulated, or does a large share of heat escape through walls and windows?
• Are the thermostats’ features actually used consistently?
• How high will energy prices be over the coming years?

If someone was already heating frugally, the extra benefit is often limited. In poorly insulated older buildings, part of any saving effectively leaks straight out through the fabric of the building. And if residents stop using the app after the first few weeks, little of the theoretical potential remains.

"Only when technology, building standards and user behaviour work together do smart thermostats deliver their full saving potential."

What households should check if a requirement is on the horizon

Even if the exact rules vary from country to country, anyone expecting a future mandate - or already planning a modernisation - should clarify a few points in advance:

• Carry out a stocktake: How many radiators are there, which valves are fitted, and how old is the heating system?
• Assess the system option: Standalone wireless thermostats, a central gateway, or integration into an existing smart home - depending on the property, one approach may be cheaper and simpler.
• Calculate payback: What will devices and installation cost, and what would a realistic annual saving be at current energy prices?
• Clarify the tenancy arrangement: In rented homes, the owner decides. Tenants should discuss early on whether and how costs will be shared.
• Keep data protection in mind: Many systems collect detailed usage data. Anyone who values privacy should look closely before buying.

Opportunities and risks of connected heating technology

Beyond the political argument, smart thermostats do offer genuine benefits: they make energy use more visible, make it easier to heat according to need, and can protect comfort and the climate - for example, through set-back programmes when nobody is home. In blocks of flats, data can also help faults get spotted sooner.

At the same time, new dependencies emerge: on wireless networks, apps, cloud services and manufacturers that must provide updates. Anyone relying entirely on connected controls could, in the event of outages, end up cold or only able to use devices in a limited way.

There is also a social dimension. Technical requirements costing several hundred or several thousand euros hit people on low incomes harder than well-off owners. Without fair support, the risk grows that climate action will be seen as a luxury for the affluent - and public acceptance will fall further.

For policymakers, that creates a twofold challenge: to use the savings potential of smart technology sensibly without financially overwhelming households, and to design rules so that investments genuinely pay off - rather than becoming yet another costly tick-box on a long list of obligations.