Heating is the single largest operating cost in residential buildings – and, paradoxically, often the least intelligent system in the house. For decades, heating has been controlled by a combination of outdoor temperature sensors, pre-set heating curves, and individual thermostats. But these systems know little about what actually happens indoors.
That is starting to change.
From reactive to predictive heating
The basic idea of Leanheat, a smart heating control system, is disarmingly simple: use indoor temperature data to steer heating, and let AI learn how each building responds to weather, outdoor temperature swings, and even local conditions. Instead of reacting after the fact, Leanheat predicts and adjusts beforehand.
Real data, real results
At EG EnerKey we have data from over 1,500 residential buildings using Leanheat. For this article we analysed a sample of ~100 buildings where Leanheat was installed in late 2022, using 2021 consumption as a benchmark.
The results:
In 2021, annual normalized heating consumption across these buildings was 31.5 GWh.
By 2025, after 2.5 years with Leanheat, it had dropped to 28.4 GWh.
That’s a reduction of 3.1 GWh annually – nearly 10% on average.
More than energy savings
Of course, there is variation. In some buildings the savings reached -20%, while in a small group consumption actually rose. But this increase was not due to inefficiency, it reflected cases where indoor temperatures had originally been too low. With sensor data, those gaps became visible and were corrected, leading to more comfortable homes and fewer complaints.
Instead of wondering why their home feels too cold or too hot, residents can now rely on stable, comfortable temperatures all season, a change that improves everyday life as much as it reduces energy bills.
Importantly, the savings are not achieved by lowering temperatures across the board. Data from Leanheat, integrated into EG EnerKey, shows that indoor temperatures remain stable and comfortable throughout the heating season.
Average indoor temperature:
November 2024: 21.76 °C
December 2024: 21.73 °C
January 2025: 21.76 °C
February 2025: 21.75 °C
March 2025: 21.86 °C
April 2025: 21.98 °C
For residents, that means apartments consistently remain within the comfort zone – warm enough in winter, never overheated in spring – without unnecessary energy waste.
Peak power makes all the difference
Another common effect after Leanheat installation is a significant drop in hourly maximum heating power. Traditional systems simply react to changes in outdoor temperature as they happen. Leanheat, on the other hand, knows what’s coming and adjusts in advance.
The result: lower peaks in heating demand. For buildings connected to district heating, that translates directly into lower tariff costs.
Example: at outdoor temperatures around -15 °C, hourly demand in one building dropped from 90–160 kW before Leanheat (H1/2021) to 80–100 kW after (H1/2025).
Smarter heating, stronger value
The evidence is clear: smart heating control does more than reduce energy use. It improves comfort, prevents complaints, and lowers tariff costs – all while giving building owners a fact-based tool to understand and optimize their portfolios.
Behind every data point are people: fewer complaints to property managers, happier tenants, and a smoother daily life for residents.
With data from 1,500 buildings and counting, EG EnerKey can show that AI-driven heating is not a promise for the future. It is already here, delivering measurable results for residential property owners today.
So if smarter heating can cut both costs and complaints – why keep paying extra?
