Finland’s constitution instructs that “the public authorities shall promote the right for everyone to housing and the opportunity to arrange their own housing” (Constitution of Finland, Section 19). It is a modest sentence and it has been taken seriously for a very long time, through loans, land purchases and allocation rules rather than declarations. Across Europe, where rents have outpaced incomes for a decade, that record is now being read with new attention: the European Commission presented its first European Affordable Housing Plan in December 2025.
What that constitutional promise looks like in practice, seventy years on, can be seen in an ordinary apartment block in Laajasalo, on the eastern edge of Helsinki, and in what a European
research project, named BuildON, is doing there.

A stock worth keeping
The decisive instrument arrived in 1949, when the Arava Act introduced low-interest state housing loans. As Finns left the countryside in large numbers, Helsinki’s housing production office used them to build almost 20,000 homes between 1960 and 1980, mostly in precast concrete, in Kontula, Pihlajamäki, Myllypuro and Laajasalo (City of Helsinki). The programme combined state-supported financing, municipal land policy and standardised construction methods to meet rapidly growing housing demand.

Today, that legacy is also a challenge: more than a quarter of Helsinki’s homes date back to 1960 to 1979 (Helsinki facts and figures 2024). Across Europe, many estates of this generation have been demolished, sold or allowed to decline. Helsinki, which owns 64.9% of its own land, has instead maintained and developed its housing stock consistently over the long term.
There is a financial logic to that, and it is a social one. In Finland’s state-supported rental housing – financed through interest subsidy loans rather than direct subsidy – rents follow the cost-price principle: they cover construction, maintenance, repairs and management, with no profit added. Heka, the City of Helsinki's housing company and Finland’s largest rental housing provider, owns around 55,000 homes housing some 96,000 residents, at rents about a third below market rates (Heka annual report 2025). Because costs are pooled across the portfolio, efficiency gains can help support affordability across the housing stock. Energy is a significant part of the costs that rents ultimately have to cover.

What a renovation settles and what it leaves
Gunillantie 6 is one of nine blocks on a single Heka site, built between 1969 and 1970. The pilot building has 32 flats, every one identical and designed for a family: 71 square metres, two bedrooms, a living room, a kitchen and a bathroom.
Between 2021 and 2024 the whole site was comprehensively renovated. Ground-source heat pumps became the main source of heat, with district heating retained as back-up for the coldest periods; mechanical ventilation with heat recovery replaced the original arrangement; solar panels went onto the roofs. Measured in the pilot building, district heating consumption fell by roughly 55% compared with the period before the renovation, according to Kirsi Korpisalo, the energy expert at Heka who runs the site’s involvement in the project. Electricity use has risen, because the heat pump runs on it, and comparable figures for that are not yet available.

The major renovation work has been done. What it did not settle is how the building is run from one day to the next, or how evenly the warmth it produces is shared between the flats. That is the question BuildON is testing here, together with Heka and the Finnish research centre VTT.

What the project adds
Anyone who has lived in an old block of flats knows the problem. Some flats can be too hot and others too cold; the building’s average temperature can look correct while few people inside it are comfortable.

At Gunillantie 6, electronic thermostats have been fitted to the radiators in every flat and in the common and service spaces, connected to the building’s monitoring system, alongside better measurement and a digital record of the building’s technical history. The main result Korpisalo reports is more even heating: the thermostats “decreased overheating and reduced the temperature variation between apartments and in the apartments”, between one flat and the next, and between rooms within the same flat. Because each radiator can now be controlled individually, unoccupied flats can be held at 18 °C while occupied ones stay at 21 °C.
There is a second reason for the timing. Since Helsinki closed its last coal-fired power plant in April 2025, the question is no longer only how much heat a building uses, but when it uses it. With VTT, the pilot is modelling energy flexibility and testing how to ease heating demand at the hours when the district heating network is under most pressure, without residents noticing.
The honest accounting matters: the 55% belongs to the renovation, not to the thermostats, and Korpisalo plainly says that the contribution of the controls alone is hard to isolate in a site of ten buildings. The renovation accounts for the reduction in energy use; the digital layer is improving how evenly that heat is distributed.

What the residents did and didn’t do
Residents were informed about the system before installation and given manuals afterwards, and again after a follow-up questionnaire. The questionnaire found that several of them were unsure how to use the equipment and, in some cases, were not aware that they were allowed to use it. Only a couple of flats use the controls actively.
Heka does not regard this as a failure. “We don’t see this as a problem because the system works independently, and Heka professionals keep track of the system and control the temperatures,” Korpisalo says. “Our aim is to provide smooth everyday living.”
That is worth noting, because much smart-building design assumes an engaged resident who will read the data and act on it. In blocks of flats generally, and perhaps especially in social housing, the better test may be how little anyone has to think about the system at all: for a large housing provider it has to work reliably without requiring continuous attention from residents. That does not remove the need for clear information: the question about resident engagement is not only whether people use the controls, but whether they know what they are allowed to control and how their indoor conditions are managed.

Beyond one block
The measure of a pilot is what the organisation does next. Heka is now preparing a tender to fit electronic thermostats at five more sites, and testing a service model alongside it, to establish how much energy the approach saves and whether it can help balance heating across its buildings.
The same question remains in most of the apartment blocks Europe built in the second half of the twentieth century: how to make them more efficient and more comfortable without replacing them. Answering it is slower work than building anew, and it depends on institutions willing to keep improving what they already own. Keeping the homes that already exist warm, affordable and worth living in is the less visible half of the right to housing. Helsinki has been practising that principle for decades.