Change is in the air in Stock­holm, Sweden’s capital city. Energy company Stock­holm Exergi is making the supply of heat to a total of 800,000 people and produc­tion of elec­tricity to the power market more sustain­able and effi­cient. The company is pursuing an ambi­tious goal – namely, to be climate-neutral by 2032.

Driven by this vision, Stock­holm Exergi is relying almost entirely on renew­able or recy­cled energy and on modern­izing the city with inno­v­a­tive tech­nolo­gies. “This includes setting up battery parks to store more energy from sustain­able sources and retro­fitting build­ings to better distribute and use elec­tricity and heat,” says Nils Berge, energy systems engi­neer at Stock­holm Exergi. However, climate neutrality will not be the only benefit for the metro­pol­itan region, as Erik Brisen­heim, Tech­nical Director at ebm-papst Sweden, explains: “For Stock­holm, a more effi­cient energy supply also means more inde­pen­dence, espe­cially in the winter months when many house­holds need heating at the same time. Until now, the Swedish capital has been depen­dent on addi­tional energy from abroad.”

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Better use of energy thanks to retrofit

In addi­tion to new district heating connec­tions, Stock­holm Exergi is relying primarily on modern venti­lation and air-condi­tioning systems for its building retro­fits. These systems are partic­u­larly needed on cold Scan­di­na­vian days. This is because venti­lating with open windows would cool down inte­riors too much and require more energy to heat them up again. Swedish build­ings there­fore nowa­days use venti­lation systems with heat exchangers, which heat the fresh air before it reaches the inte­rior. However, build­ings built in the 1970s and earlier only have an exhaust fan without heat recovery. “In addi­tion, many systems still use old AC roof fans that are diffi­cult or impos­sible to control, so they run at full power or not at all. There is often nothing in between to cover the actual demand for fresh air. And that costs the oper­a­tors and resi­dents unnec­es­sary energy and money,” adds Nils Berge.

In an older resi­den­tial building in the Öster­malm district, however, Stock­holm Exergi shows how “effi­cient venti­lation” can set a prece­dent. For the retrofit project at Gyllen­stierns­gatan, the company is relying on a complete solu­tion from ebm-papst with the MXRC III EC rooftop fan and the new Intel­li­gate Air X gateway controller from ebm-papst neo, including sensors and cloud connec­tion. The rooftop fan is not only impres­sive due to its energy-effi­cient perfor­mance. “It is also very quiet and vibrates very little so as not to disturb the resi­dents,” adds Erik Brisen­heim.

The gateway controller can send data without having to interact with the customer’s network.

Erik Brisen­heim, Tech­nical Director at ebm-papst Sweden

The gateway controller also connects the fan to various external sensors and to the cloud. Thanks to the inte­grated Narrow Band IoT modem, the Intel­li­gate Air X can commu­ni­cate with the cloud and transmit sensor data inde­pen­dently of the local network. “This also means that the gateway controller can send data without having to interact with the customer’s network,” says Erik Brisen­heim. “The data trans­mitted allows the venti­lation system to be moni­tored remotely and controlled contin­u­ously and auto­mat­i­cally. This makes it easy to provide venti­lation exactly when it is actu­ally needed, thereby saving a lot of energy.”

Improving life, one project at a time

The retrofit is a win-win situ­a­tion for all parties. Thanks to the avail­ability of measure­ment data and analyses via the cloud, owners have a perfect overview of how often the building is venti­lated and how much energy this consumes. “For resi­dents, the main benefit of the new venti­lation system is greater living comfort because it improves the indoor air quality. This is because the sensors and gateway controller measure several para­me­ters in the exhaust air and controls the flow for the venti­lation as required,” says Erik Brisen­heim. “The system can also detect what the weather is like outside and adjust the venti­lation accord­ingly. As a result, resi­dents also save overall utility costs, as the system is not constantly running and consuming elec­tricity.”

The MXRC III EC rooftop fan supplies the entire resi­den­tial building in Gyllen­stierns­gatan with fresh air.

The system can be contin­u­ously adjusted to venti­late as required. This saves elec­tricity and money.

Always in view: The venti­lation system data can be viewed and eval­u­ated live via the cloud.

The retrofit project in Gyllen­stierns­gatan was just the begin­ning: Stock­holm Exergi and ebm-papst are plan­ning to make further build­ings in Stock­holm more energy-effi­cient.

So the retrofit in Gyllen­stierns­gatan will not be the last. On the contrary: together with ebm-papst, Stock­holm Exergi is already plan­ning more retrofit projects in Stock­holm, mainly in build­ings belonging to Swedish housing coop­er­a­tives, or “Bostad­srätts­förening” (BRF). The resi­den­tial building in Gyllen­stierns­gatan was there­fore just the begin­ning and a blue­print for Stock­holm Exergi to modernize other build­ings and make them more energy-effi­cient – all with the main aim of reducing Stockholm’s emis­sions.