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Energy efficiency and improved
indoor climate in a historic building

Historic building
Easy Access
Envistar Flex
ThermoCooler HP reversible heat pump

Formannen | Stockholm

Formannen in Stockholm is a historic building with a history dating back to the 17th century. Today, the Swedish Society for Nature Conservation is located in the building. This is Sweden's largest environmental organisation, and they also have Sweden's most sustainable office. When it was time to improve the building’s energy efficiency and indoor climate, they contacted the consulting firm Exengo in Stockholm to help them overcome the challenges.


Sustainable indoor climate all year round

The Nature Conservation Association wanted to find an overall solution with heating and cooling combined, to create a pleasant and sustainable indoor climate all year round. Also, they didn’t want to damage the historic building by tearing down walls or opening up the ceiling.

"One of the challenges was that the plant room for this air handling unit was located in the middle of the building on the third floor, making it difficult to access", says Thomas Adermark at Exengo.


In this video, Bernd Hake, together with representatives from the consulting firm Exengo, shows a project for energy efficiency and improvement of the indoor climate in an older building in Stockholm.


Module-based site transportation with Easy Access

The solution was the Envistar Flex air handling unit with the integrated reversible heat pump ThermoCooler HP, in an Easy Access configuration. In that way, the unit could be transported in modules through narrow passages and then easily assembled in the plant room.

Heating and cooling combined with ThermoCooler HP.

The reversible heat pump ThermoCooler HP can be integrated into our Envistar Top and Envistar Flex air handling units. A unit with an integrated reversible heat pump is more energy-efficient than a traditional cooling installation with an external cooling unit and heating battery.


Air handling unit with low installation and operating costs

Victor Andersson at Exengo says that:

"with ThermoCooler HP, we delivered a complete and cost-effective solution where the reversible heat pump cools the supply air in the summer and heats it in the winter. A heating battery and associated piping were not needed."

The new ventilation solution provided major savings:

"The combination of Easy Access and ThermoCooler HP resulted in low installation and operating costs," Victor adds.

The HVAC Designers Victor and Thomas from Exengo together with Bernd from IV Produkt.

The HVAC Designers Victor and Thomas from Exengo together with Bernd from IV Produkt.



  • Easy site transportation through narrow passages.
  • A complete solution for cooling and additional heating.
  • No need for an extra heating battery.
  • Associated piping was not necessary.
  • Low installation and operating costs.

Envistar Flex and ThermoCooler HP with cooling and additional heating combined.

Envistar Flex with the integrated reversible heat pump ThermoCooler HP in the plant room at Formannen in Stockholm.


In this project
End customer: Naturskyddsföreningen
Consultant: Exengo Installationskonsult AB
Installer: Airteam Creovent AB

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