Nastolan Aurinkolinna’s story is truly remarkable. The Art Nouveau building, which was built in the early 1920s to treat children with tuberculosis, has served as a military hospital, a nursing home and a reception center for asylum seekers during its hundred years of existence. In the early 2010s, the abandoned building was restored to its old glory when the castle was completely renovated into a residential building. A comprehensive HVAC renovation, upgrade of doors and windows, and insulation work are only a small part of the measures taken to revitalize Aurinkolinna.

One of the greatest secrets of Aurinkolinna seamlessly intertwines history and modern technology. As a part of the renovation, a state-of-the-art heating system was introduced in Aurinkolinna. The system which utilizes heat recovery of the exhaust air in the heating of the property. Matti Pietilä, a resident of the house, is excited about the advanced system.

– The introduction of a modern heating system as part of the renovation was a significant thing for us also on a symbolic level: the old building got a new life, but without sacrificing its soul. The benefits of heat recovery are easy to see: we save a lot of energy and thousands of euros a year in energy by extracting heat from the exhaust air instead of wasting it through ventilation. In addition, the entire system is of Finnish origin.

Finnish innovations

The system was supplied by HögforsGST, who have been manufacturing heating systems for almost twenty years. According to CEO Antti Hartman, the project was challenging but rewarding.

– Old and historically valuable sites should always be treated with respect, so making compromises is quite usual. We have implemented several different heat recovery projects for old properties, each with their own special characteristics. Experience has shown that you should always prepare for surprises, Hartman says with a smile.

– In this case, the façade is protected, so for example the pipelines of the heat recovery system could not be built to run along the external walls of the building, as we usually do.

The problem was solved by taking the pipeline through a stairwell to the heat distribution room. According to Pietilä and Hartman, the solution works, as the pipes was encapsulated in such a way that the clean overall look of the stairwell was maintained. The piping is also easily accessible for maintenance.

Fiksu Control System improves living comfort

The living spaces are heated by water circulating underfloor heating, which is controlled by Fiksu Control System developed by HögforsGST. The system collects temperature data from both apartment-specific temperature sensors and outdoor air. Based on the data collected, the system is able to optimize energy consumption, which improves the energy efficiency of the property.

– The operation of modern hybrid heating systems can be compared to, for example, a hybrid car: the control system switches between district heating and heat pump energy just like a hybrid car does with electricity and gasoline, Harman compares.

With the automatic heating system, the living comfort of the old building is also on a same level, if not better, than new 21st century properties. The system is completely remotely controllable, so the heating of the entire property can be controlled from a phone or tablet. In addition, the system produces reliable consumption reports, savings calculations and energy saving tips. The system also sends an automatic alarm of fault situations, which contributes to increased housing safety.

HybridHEAT is also well suited for old properties

Hartman, who has implemented several heat recovery systems with HögforsGST, thinks Nastolan Aurinkolinna is a great example of a successful renovation.

– The old building got a new life as an energy-efficient home. This proves that the smart heat recovery system is also well-suited for older properties. Kurjenlinna residential area, which is currently being built in Turku, is another example of the successful combination of an old property and modern technology.

Matti Pietilä is satisfied with the functionality of the entire system and the energy savings it makes possible.

– We save a lot of energy compared to a ”regular” heating system, up to 50%.

Pietilä is also proud of the environmental friendliness.

– There has been a lot of public talk about climate issues. With this new heating system, we can say that we have done a real environmental act. As energy consumption decreased, Aurinkolinna’s carbon dioxide emissions decreased by multiple tonnes at the same time.