Stena Fastigheter owns and manages more than 380 properties in Sweden and abroad. In total, the company consumed nearly 63 million kilowatt hours for its Swedish properties last year. By the end of this year, the company expects to have solar panels on close to 80 of its Swedish properties, with a capacity to produce around 3 million kilowatt hours per year. 

“In three years’ time, 2026, the goal is for half of our electricity to be self-generated,” says Jakob Nilsson, Chief Financial Officer at Stena Fastigheter. “This will contribute to a reduced carbon footprint, more satisfied customers and lower energy costs.”

UNIQUE INVESTMENT IN SOLAR POWER PLANT IN URBAN ENVIRONMENT 

In Uppsala, Stena Fastigheter is now exploring the possibility of building its largest rooftop plant to date. 

“If the solar power plant becomes a reality, it will be unique in that it will be built in an urban environment,” says Mattias Sikström, Energy and Environment Manager at Stena Fastigheter Stockholm. “It will be installed on some 40 rooftops with a capacity to produce 2.1 million kilowatt hours per year. That’s more electricity than we presently use in these buildings. Part of our preparatory work therefore involves determining how the surplus energy will be used. Can it be transferred to other of our properties, or sold locally in Uppsala? Previously, Swedish legislation had prevented this, but the legislation has now been modified so that it will be easier to produce sustainable solar power in one building and then transfer it to others.”

Another large solar power plant could become reality in the Ekebo district of Stockholm, where Stena Fastigheter is looking into the possibility of creating a solar power plant on 50 rooftops with almost the same capacity as in Uppsala. 

“We installed our first solar panels on two properties in Stockholm three years ago,” says Mattias Sikström, Energy and Environment Manager at Stena Fastigheter Stockholm. “By the end of 2022, we will have solar panels on 54 buildings in the Stockholm area. Together they have the capacity to produce 1.8 million kilowatt hours per year. If we build the Uppsala and Ekebo solar power plants, we will triple our production of solar power. We’re also looking at other properties where solar cells can be installed.”

The initiative for solar cells applies all the company’s properties, which are mainly in the major cities of Stockholm, Göteborg and Malmö. 

REDUCED USE OF HEATING NEEDS WITH THE HELP OF AI

Over the past decade, Stena Fastigheter has worked strategically to reduce the use of heating, electricity and water, and with very good results. Between 2010 and 2020, heating was reduced by 30%, building electricity by 38% and water consumption by 21%. Stena Fastigheter is now taking the next step and working with artificial intelligence (AI) to reduce the use of heating.

“Our traditional ways of regulation have been rather blunt,” says Henrik Hansen, IT architect at Stena Fastigheter. “In short, when it has been a certain temperature outside, we have sent out hot water with a certain temperature to the radiators, in some cases with a certain adjustment for the current average indoor temperature. But there is a thermal inertia in the buildings, and by the time the heat has warmed up the apartments, the temperature outside has already changed. With the help of a mathematical algorithm that learns how the building reacts, we can more accurately steer towards what the conditions will be in the future. The tenants get a more even indoor climate at the same time as we don’t have to use more heat than necessary.”

TEST PERIOD DURING THE WINTER

In the spring of this year, Stena Fastigheter tested the algorithm, which among other things, continuously weighs in the building thermal inertia, the outside temperature, the indoor temperature in the apartments and weather forecasts. The test, which was carried out at two properties in Stockholm, showed that the company saved 10-15% in heating compared to traditional regulation. In the coming autumn and winter, work will be scaled up as 20–30 more properties will be connected to AI.