When the zero-energy neighbourhood Solallén was being built in Växjö, Assemblin contributed with heat and sanitation installations. This included, among other things, free cooling, which is a sustainable way to create a comfortable indoor climate. In 2017, the project was named one of Sweden’s most sustainable.

  • Skanska

A competition was organised by Sweden Green Building Council to find Sweden’s five most sustainable building projects. Solallén, which was built by Skanska, was one of them. The projects later represented Swedish sustainable construction at the World Sustainable Built Environment conference in Hong Kong in 2017.

Free cooling

When the Solallén townhouse neighbourhood was built, Assemblin was responsible for the heating and sanitation installations. One idea that was developed was to install free cooling, which is a sustainable way to create a comfortable indoor climate using a geothermal heat pump system.

“During the summer, the cold water in the rock is used to lower the temperature. The refrigerant is circulated into boreholes and cools the ventilation air for the residents. During the colder months of the year, the geothermal heat pump heats up the buildings using underfloor heating,” says Daniel Fredriksson, Project Engineer at Assemblin VS in Växjö.

Free-cooling technology is especially useful in new buildings with a large number of windows, which can easily get hot during the summer.

“But it is also possible to install a system like this in existing buildings, if they have a geothermal heat pump installed,” says Daniel.

A partner with the right experience

Assemblin was awarded the assignment because Skanska needed a partner with experience of this particular technology,” says Lars Nilsson, Project Manager at Skanska in Växjö, adding:

“The collaboration with Assemblin has worked very well during both the design and production phase.

The Solallén neighbourhood, which is self-sufficient in terms of energy, was built and designed by Skanska in 2014 and 2015 and is the first in Sweden to be built according to Netto Nollenergi, a net zero energy scheme. This means that the buildings produce more electricity than they need for heating, hot water and communal electricity. This is possible thanks to the solar cells on the roof, supply and exhaust ventilation (FTX) and the aforementioned geothermal heat pump and free cooling. Surplus electricity during the summer months can be sold on the energy market.

Solallén is the first residential area to achieve the highest level, deep green, on the Skanska Color Palette, which shows how sustainable a project is.