Renovation improves the energy efficiency and comfort of student housing in Jyväskylä

The 50-year-old student housing towers in the Kortepohja district of Jyväskylä have been refurbished one at a time in recent years. In addition to the updated yards and shared use facilities, Sweco’s HVAC and building services engineers found energy-efficient and comfort-improving technical solutions for the buildings.

The Soihtu business unit of the Student Union of the University of Jyväskylä (JYY) began planning the renovation of the Kortepohja student housing towers in 2016. The aim was to modernise the technical solutions of the five buildings (A–E) completed between 1968 and 1972. Construction was not considered because the building facades are protected and the students are satisfied with the distribution of the housing units.

“Demand remains highest for studio flats, of which the towers contain 720 in total,” says Soihtu’s Chief Real Estate Officer Kimmo Moilanen. At the same time, the Rentukka restaurant between the A and B buildings was refurbished to serve as a living room for the students. “The average floor area of the flats is only 21 square metres, so we added services such as a lunch restaurant and gym to Rentukka to facilitate day-to-day living.”

The renovation will also improve the buildings’ yard areas, and Sweco’s HVAC experts helped design stormwater management on the challenging plot. The area features a web of criss-crossing power, district heating and water pipes. “Moreover, groundwater is fairly high up in the area, which means that rainwater cannot be absorbed into the soil, but retention is possible,” says Sweco’s Hannu Purola, who was responsible for the control of HVAC and building services engineering.

Suitable indoor temperatures in summer and winter

One of the most important targets of the renovation was the buildings’ HVAC and building services solutions. Clogs and leaks had been observed in the old cast iron sewer piping. “We wanted to improve comfort and energy efficiency, and connect the technical solutions to a remotely-monitored building automation system,” Moilanen says.

In terms of indoor conditions, it was key to take the buildings’ vast wall surfaces into account, as they increase indoor temperatures during warm periods in summer. “We carried out temperature simulations and opted to equip the flats with extractor hoods that enable 6–8 hours of overnight cooling instead of the normal 90–120 minutes,” Purola explains. The occupants are also advised on how to use the new technology and save energy.

In order to confirm the conditions and gain an overview of the building’s heat balance, the HVAC engineers measured the room temperatures of the corner flats, which cool down first in winter. “The heating system’s faults are revealed quickly when the automation notifies maintenance of the corner flats becoming colder.”

Building age does not preclude energy-efficient technical solutions

In 2020, JYY published a climate sustainability roadmap which aims for carbon neutrality by 2025. “For the towers, the relevant values have been adhered to from the start,” Moilanen says.

Energy-efficient technology has been used in every tower, even though many of the solutions are more typical in the construction of new buildings. “We were able to make the mechanical air supply and extraction work despite the buildings being old and protected,” Purola explains. “In addition to this, we were able to equip the towers with modern heat recovery solutions.”

Different solutions were needed in the first two towers, because sauna facilities were built in the attic floor: we had to make room for the ventilation machinery elsewhere. “16 ventilation units have been distributed across the corridor ceilings of buildings A and B, and extraction is handled with two roof extractors,” Purola says. “The heat pump recycles up to 70% of the heat inside the building.”

Information models facilitate worksite control

The need for arranging competitive bidding for the engineering and control was assessed separately for each tower. For this reason, the parties involved have remained largely the same. “This has enabled us to refine the details with each new building to be renovated,” Moilanen says. He also feels that the decision to centralise HVAC and building services engineering and oversight to Sweco was a good one. “All aspects of the worksite and design collaboration have worked well.”

In terms of control, the information models have been very helpful. “Building services engineering contractors in Jyväskylä are well-informed, and the information model has been used by the supervisors and worksite manager through their smartphones,” Purola explains happily. The model has helped with modifying the plans as needed. “We have been able to use the information model to determine alternative routes for the technical solutions, should the need arise.”

HVAC and building services contracting in Jyväskylä is at such a good level that the overseer mostly only needs to ensure that the overall HVAC processes work in the way intended by the designer. “This ensures that all individual solutions serve a successful end result.”

“We wanted to improve comfort and energy efficiency, and connect the technological solutions to a remotely-monitored building automation system.”
– Kimmo Moilanen, Soihtu

“In 2020, JYY published a climate sustainability roadmap which aims for carbon neutrality by 2025. For the towers, the relevant values have been adhered to from the start,” Moilanen says.
– Kimmo Moilanen, Soihtu

“Since the parties involved have remained largely the same, we have been able to refine the details with each new building to be renovated.”
– Kimmo Moilanen, Soihtu

“All aspects of the worksite and design collaboration have worked well.”
– Kimmo Moilanen, Soihtu