Skip to content


Berliner Energietage: smart thermostat control actively involves residents in climate protection 

On May 5 2023 the digital version of Berliner Energietage came to a successful end. More than 60 events took place over the three days of the online congress. In the panel discussion “Digital Control: Housing Companies and Tenant Households Working Together for the Heat Transition in Existing Buildings”, Dr. Dirk Then, CEO of the noventic group, together with Dr. Christian Osthus, General Counsel (Justiziar) at the IVD Federal Association, Ralf Michels, Member of the Executive Committee of the VDIV and Professor Kunibert Lennerts, Professor of Facility Management at the Karlsruhe Institute of Technology (KIT), looked into the role of residents in climate protection in the housing industry and how to involve them in the heating transition.

One topic that the panellists could not overlook was the German Federal Climate Change Act (Klimaschutzgesetz 2045) and the associated Federal Government provisions. The most recent example is the amendment of the Building Energy Act (Gebäudeenergiegesetz). The sometimes short lead times pose challenges for those responsible for implementation, as IVD legal advisor Dr. Osthus confirmed: “We accept the overriding goals of climate protection. That has to be done.

The problem is the speed that the Building Energy Act demands from the owners and managers who have to implement it.

Dr. Osthus

“This must be orchestrated. It adds a major workload on top of what the administrators already have to do. In addition, we need clarity very quickly. This is all still somewhat tenuous and rather vague. We would like to quickly see legal certainty and a little leeway as far as implementation is concerned, plus clear perspectives regarding financing.”

Snap survey with a shock result

VDIV expert Michels added:

We have a great deal of uncertainty in the market, especially regarding the tight schedule involved: Homeowners' associations do not move quickly, even if you try to be quick – as a rule, there is one meeting a year. We conducted a snap survey of VDIV members and asked how they see the situation. This was a shock: 96% said that they would not be able to implement this financially in their owners’ association. Of course there are plans to increase allocations to reserves. Nevertheless, this has to be paid for first, and on top of this come staff shortages: 46% say they cannot cope with it in the short term. We have to find a way that can be implemented.

Ralf Michels

So far, little attention has been paid to the role of tenants

In light of these pressing concerns it is rather surprising that government provisions for building sector decarbonisation focus chiefly on structural and technical optimisation. To date scarcely any thought has been given to the actual residents.

noventic CEO Dr. Then notes that: “It is important for us to address building physics. However, over recent years we have found that optimising the structural physics of the building envelope or the relevant energy technology is not in itself enough.

Not enough attention has been paid to human psychology. Nowhere more than in the real estate industry, though, getting households involved is hugely important!

Dr. Dirk Then

A study by Professor Pfnür shows that residents are clearly aware of their role and want to take action. We don't pay enough attention to them when devising our solutions. We still don't give them adequate resources.

Low-investment and immediately available via retrofitting

One way of getting residents involved in the building sector heating transition is through smart thermostats. Dr. Then explains: “Affordable housing has become a central issue of political debate, one that will keep us occupied over the next few years. Thinking about residents’ involvement, what tools do they get?

If we assume 6% savings for one degree of heat reduction, the question remains: How am I supposed to regulate this one degree if I only have the abstract numbers one to five on my thermostat?

Dr. Dirk Then

“That's what I mean by tenant involvement: we're making things too difficult and too abstract. We’re still not making enough use of the opportunities offered by digital technology.” Smart thermostats could help here: “What we need must firstly be low-investment, secondly immediately available and, above all, retrofittable, i.e. It must work with existing radiator valves. Given these three criteria, the smart thermostat solution is ideal for the large building stock. It will allow energy costs and carbon footprint to be optimised even for the worst-performing buildings in energy terms. If we rely solely on renovation of the building envelope we will be unable to move fast enough given the climate targets in place.” His conclusion: “This is a great solution that can help us to achieve immediate results.”

Experiences from flagship projects

In intensive pilot and flagship projects the consumer product was specially adapted to the residential housing industry's needs. In one of these pilot projects Ralf Michels managed to gain initial experience with the device after it had undergone further development. “We are also property developers. We build holiday properties which are seldom occupied, people only come for weekends, and not at all in bad weather. To ensure that the apartments and buildings do not cool down unnecessarily, many simply leave their heaters on. That's what induced us to install smart thermostats. The residents can use an app to switch on their heaters half an hour before they arrive, and they are delighted because they walk into to a warm apartment while saving a lot of energy. We installed the smart thermostats in ten apartments, eight went along with it, and five actively and frequently used the app.

I'm a big fan of smart thermostats. I think that basically, the willingness is there. I would cater for those who feel like it. I reckon that’s more than we think.

Ralf Michels

Effectiveness of smart thermostats scientifically confirmed

Experiences in practical use were scientifically investigated by KIT during the 2022/2023 heating season, and their findings have since been published in a study. The results confirm the experience gained from the first pilot phase. Professor Lennerts: “Over a period of three months we compared two apartment buildings partially fitted with smart thermostats with one apartment building not fitted with them. All three were built in 1972 and were of energy efficiency class D. 19% of all apartment buildings in Germany are in this energy efficiency class. During the test period, the partially equipped houses achieved a heating energy saving of 21% as compared with the reference property, namely the unequipped apartment building. Purely due to the smart thermostats. If we now hypothetically assume that the apartment buildings had been fully fitted, and we extrapolate the findings, this would give us a saving of no less than 31.5%. To be on the safe side, we compared the consumption figures with the buildings’ historical consumption data. 

Adjusting for weather-related factors and the special circumstances of the energy crisis, and resultant changes in heating behaviour in some cases, the study still reveals a significant saving of 15.5% for the apartments fitted [with smart thermostats].

Prof. Lennerts

The question of whether the solution will also fall on fertile ground in practice for those who will order it at the end of the day, i.e. the landlords and managers, was answered by Dr. Osthus as follows: “I absolutely can imagine [them going for] smart thermostats. This allows you to take people with you. We advise our members to use smart thermostats in their homes because we believe that we can achieve a lot with them.”

Panellists’ conclusions regarding the issue of digitisation

At the end of the panel discussion, the panellists came to address the digitisation of the building sector. Everyone agreed that there was no alternative if the German government's ambitious climate targets are to be achieved. Dr. Osthus' assessment: “The degree of digitisation in our real estate is extremely low. The building stock was constructed at a time when there was hardly any digitisation. We are driving digitisation in the building sector because we see enormous potential savings there. However, we know that many administrators are still reluctant because they are overwhelmed by everything they have to do on a day-to-day basis.” Dr. Then added: “We are entering an era when tenants have charging stations in their basements. These are situations that didn't exist five to ten years ago. We're seeing a convergence of complex electricity-based assets in real estate that we must somehow orchestrate. The issue of digitisation in real estate is one that every owner and manager will have to address over the coming years.

As an industrial company our task will be to offer tools and facilitate the work of managers and owners. It’s about forming networked systems.

Dr. Osthus

“We must reach a point where we provide such systems with open interfaces and design them to be open-system and offered in a spirit of partnership.” 

We would like to thank Berliner Energietage and all the panellists, as well as viewers of the live stream, for the successful discussion.

To overview

Thomas Ahlborn

Head of Corporate Marketing, noventic group

Since 2013, Thomas Ahlborn has held various positions for companies of the noventic group, focusing on the theme of new supply concepts for neighbourhoods and buildings.

Also interesting