Enormous energy efficiency when buildings and rock store energy for the commercial Metropol building in Sundsvall

There is feverish activity in the expansive commercial building Metropol located on Universitetsallén in Sundsvall. Entrepreneurs, students, associations and restaurant-goers meet in a welcoming, creative environment. A metropolis that enjoys energy efficiency above the standard with its air heating and cooling.

”Because the 16,000 square metres of property are heated and cooled through ventilation and not via radiators, it required a great deal of courage to invest in ground source heating and solar. But Diös Fastigheter had just that courage and it has become a wonderful example of attaining worldclass energy efficiency using ground source heating and system solutions,” says Tommy Landin, salesperson from NIBE Energy Systems.

Up until 2015, the Metropol building on Universitetsallén had its entire heating demand met by the local district heating grid. When the building was in need of cooling, their 200 kilowatt air conditioners needed to kick in. With its expressed sustainability profile and annual energy consumption reduction (a target of minus 3 percent in 2019), the listed property company Diös decided to start drilling. NIBE’s powerful F1345 ground source heat pumps and 940 solar panels were installed. Diös Fastigheter’s energy optimiser Fredrik Karlström claims that they now have very high energy efficiency.

”Following our responsible action framework, we optimise our properties to make energy consumption more efficient and to provide a good indoor climate for our tenants. We are also decreasing our environmental footprint and contributing to a more sustainable economy through efficient use of energy. As it is rather uncommon to have air heating and cooling in such a large building, we are very pleased with our investment. It is an excellent system solution that utilises the energy found in the rock for heating and cooling. The greatest benefit is all the passive cooling we get during the summer. We have been able to replace our previous cooling units,” says Fredrik Karlström, energy optimiser of Diös Fastigheter in Sundsvall.

Passive cooling appreciated

Air heating and cooling make for a good indoor climate. In the winter, energy is supplied to the building through the main ventilation and heating batteries that heat the supply air of each floor. In the summer, the supply air is cooled from passive cooling from the rock. By ventilating the building through the floor, the construction itself is warmed and cooled. At the same time, the concrete building has a storage effect due to the inherent inertia and the rock it rests upon. Thanks to NIBE’s heat pumps and a cohesive ventilation and control system, it was possible to remove the old cooling units.

”Cooling units are expensive to operate and have a limited life span. We now charge the boreholes with cooling during the winter while we extract heat to then use the cooling during the summer. In the autumn the cycle starts again and we extract stored heat from the rock. An amazing cycle, thanks to the heat pumps. The accumulation effect really is valuable, sustainable and reliable,” says Fredrik Karlström.

Diös Fastigheter invests in responsible action

Diös wants to be part of creating cities in which companies wish to establish themselves and people want to live, work and socialise in for the long-term. Environmental certification is an assessment of how environmentally sustainable a building is. From a certification system, buildings are awarded certificates that show environmental performance. The commercial Metropol building currently carries the BREEAM In-Use certification.

”Our environmental efforts are ongoing. In addition to installing ground source heat pumps, solar panels and exhaust air recycling, we have exchanged old heat and ventilation fans with new, efficient fans in order to reduce our total energy consumption. We have a great number of NIBE’s heat pumps in our ranks. Their function and energy efficiency are excellent, they are reliable and they play an important role in our long-term sustainability efforts. Our experiences with NIBE’s air/water heat pumps are just as good and they are well suited in many projects, such as recycling extract air from ventilation units or as an alternative to ground-source heating,” Fredrik Karlström, energy optimiser of Diös Fastigheter in Sundsvall, concludes.

Commercial Metropol building, Sundsvall

• Commercial Metropol building, built in 1986, is on Campus.
• 16,000 square metres and about 50 operations.
• Owned by Diös Fastigheter, who invested in a new energy system in 2015.
• 4 x NIBE F1345-60 kW. 26 bore holes. A solar panel installation of 940 panels and output of 132 kW.
• BREEAM In-Use certificate.