This is what our suppliers say about Open District Heating

H&M – “Closing the Loop” with heat recovery

Reuse of resources and renewable energy are obvious choices for H&M

Global fashion brand H&M has been a supplier to Open District Heating since the initiative was launched in 2013. The company was one of the first to join when Stockholm Exergi invited data center operators to collaborate on developing a new concept for recovering excess heat.

Reusing resources and using renewable energy is part of H&M’s business strategy. For example, H&M was first among multinational companies to launch a global program to collect used clothes for recycling. Based on this initiative, in 2014 H&M launched its first recycled fashion collection. Today, new denim items that are made from material from collected garments are available to buy in their stores.

H&M is now present in 59 countries. As the company continues to grow globally, its online turnover is increasing and expanding in markets outside Europe and the US. As a leading international fashion company, with one of the EU’s most valuable retail brands, it has been critical for the company’s commercial and strategic success to develop a reliable, efficient, and sustainable information and communication technology (ICT) infrastructure.

”We’re delighted with the results of Open District Heating. It gives us the opportunity to make an already efficient data center even better. The simple connection to Stockholm Exergi’s network has given us the opportunity to recover energy that would otherwise go to waste. As a bonus, we’ve doubled our cooling system’s redundancy rate.”

Johan Holmberg, Data Center Specialist, H&M

Reducing the company’s environmental impact: a top priority
Reliable power supply and competitive prices for renewables is what has driven H&M to continue to consolidate its data centers in Sweden. The country’s outdoor climate also offers favorable conditions to use technologies such as free cooling and heat recovery.

In 2010, H&M opened a new global data center in Stockholm. The facility is designed for the long-term in terms of efficiency and sustainability. Reducing the company’s environmental impact and successfully “closing the loop” are two of H&M’s top priorities.

The data center only uses electricity produced from renewable sources and consumes lower amounts of power than in the past. This is partly due to a focus on achieving higher utilization rates, improved spatial planning, more energy efficient hardware, and cooling with a combination of free cooling and heat recovery. Furthermore, H&M continually monitors and optimizes operations at the facility.

During the first two years that the data center was operating, 2011-2012, it was exclusively cooled by a local cooling system. Cooling coils in the computer room are cooled with cold water, which circulates in a closed system. Using heat exchange, the cooling water system is cooled by an external loop that is connected to cooling towers, located outside. The two cooling towers thereby provide free cooling throughout much of a typical year in Stockholm.

A supplier to Open District Heating since 2013
H&M was one of the very first companies to join Open District Heating in 2013. Through its co-operation with Stockholm Exergi, its cooling system at the data center was fitted with a connection to the district heating network. This enables the data center to recover excess heat on days when the ambient outside temperature falls below 7°C. This amounts to some 4,300 hours in a typical year.

Furthermore, the new installation and the agreement with Open District Heating now means that the data center has an extra cooling option, available as a reserve during the remaining hours of the year.

It was straightforward to connect H&M’s facility to Open District Heating. The existing cooling loop was connected to a heat exchanger and a circulation pump at the same time. The other side of the heat exchanger was connected directly to Stockholm Exergi’s district heating network.

Cooling of the data center now allows cooling water to be heated to a temperature of 20°C before excess energy is transferred to Stockholm Exergi’s system and transported to a large heat recovery plant in Hjorthagen, just outside central Stockholm. With help of four large heat pumps that have a combined recovery capacity of 24MW, the temperature of returned heat from the data center is increased to an intermediate level, prior to being mixed with high temperature water from the Hjorthagen plant’s cogeneration process for distribution to district heating customers.

Between 2013 and 2015, the data center’s load virtually doubled. H&M is now able to recover energy and make annual deliveries of up to 1,700MWh in heat to Stockholm Exergi’s network. This amounts to the heat use of some 350 Stockholm inhabitants.

After several years’ experience of heat recovery at the data center, in 2017 H&M decided that their next data center, planned to open in 2018, would also recover heat. For this data center, H&M is investing in an installation where they generate data center cooling themselves with heat pumps in a redundant N+1 solution and deliver excess heat directly to Stockholm Exergi’s district heating network. Under this model, Stockholm Exergi pays for capacity (kW) and energy (kWh) dependent upon outside temperatures. The data center is scheduled to have an IT capacity of 1MW, and projected to be able to heat some 2,500 modern apartments.

Bahnhof Pionen – Profitable recovery with Open District Heating

Open District Heating gives the data center a competitive advantage

Below the Vita Bergen park in Södermalm in Stockholm, the internet supplier Bahnhof has transformed an old rock cavity into a futuristic data center, Bahnhof Pionen. The space now houses row upon row of cabinets, filled with computer equipment put there by Bahnhof’s customers. And the cabinets are heated up. With increasingly densely packed and powerful hardware, a modern data center becomes very energy intensive, and the cooling system has to be dimensioned to handle this.

When Bahnhof took over Pionen in 2007 and rebuilt the rock cavity into a data center, conventional cooling equipment was installed. The excess heat from the cooling plant facility was carried away by fans and released into the air outside the door to Pionen, where a characteristic plume of steam revealed that the business inside was wasting heat. But already from the start, Bahnhof was thinking about doing something better with the surplus heat. There was enough surplus to provide heating to hundreds of apartments and Pionen is located in one of Sweden’s most densely populated areas, in Södermalm in Stockholm.

So why not re-use the energy? At the same time, Stockholm Exergi was looking for pilots for its project Open District Heating®, which gives companies an opportunity to sell their surplus heat to the city’s district heating network.

The amount of compensation that Stockholm Exergi pays Bahnhof for the supplied heat depends on the outdoor temperature. On a cold winter’s day one megawatt hour can be worth ten times as much as on an ordinary summer’s day. Bahnhof still knows that it has made a good investment.

”We are talking about a new business model that makes it more financially viable to build a data center near a district heating network than on a site where land is cheap.”

Gustav Bergquist, Chief Technology Officer, Bahnhof

Bahnhof has deliberately chosen to locate its server halls in central locations. Primarily because it enables the company to be close to its customers. But the sale of excess heat via Open District Heating® has also resulted in a new way of looking at the financial aspect which strongly supports Bahnhof’s strategy. Bahnhof believes that the financial conditions for IT operations will change substantially thanks to the opportunity to sell energy.

Sustainability aspects are also becoming increasingly important. Today customers of the IT companies demand that suppliers ensure that their production is sustainable and adapted to the environment, which gives Bahnhof yet another clear competitive advantage.

Interxion Kista – Cost-efficient cooling and heat recovery as a service

Cost-efficiency and heat recovery with Process Cooling 14°C

Today it is not enough for data centers to offer stable and reliable services. There is also increasing demand for solutions to be sustainable and energy efficient. This is fully in line with the use of Process Cooling 14°C by Stockholm Exergi, a service specially tailored for data centers.

Interxion is a leading European supplier of data center services with operations in eleven countries. In Kista, just north of Stockholm, Interxion has more than doubled the area and capacity of its data center in the past few years. Since fall 2015 Interxion is using Process Cooling 14°C in Kista. The partnership with Stockholm Exergi for delivery of both cooling and heat recovery as a single service is unique in its kind.

The cooling and heat recovery for Interxion’s data center in Kista is provided by Stockholm Exergi’s heat recovery plant in Akalla and is delivered via the district cooling network. Process Cooling 14°C is a simple, safe and clean method based on chilled water cooling. At Interxion, a heat exchanger and a circulation pump is all that is required to cool the data center’s internal chilled water loop.

In the process the excess heat from the data center is recovered and returned to Stockholm Exergi where it enters large heat pumps that produces district heating. In this way heat that was previously simply rejected into the open air can now heat thousands of homes. At the same time, Interxion’s costs are reduced, as it is compensated for the recovered heat.

Process Cooling 14°C offers a solution in which environmental and financial interests go hand in hand.

Driftsäkerheten för Processkyla 14°C är hög året runt och skötselbehovet minimalt. Tjänsten innebär en minskning av både energiförbrukning och driftskostnader och erbjuder en mer miljövänlig kylning jämfört med lokala kylmaskiner. Ytterligare en fördel är att installationen tar mindre plats än traditionella kyllösningar. Dessutom minskar behovet av att köra fläktar vilket förbättrar närmiljön.

GleSYS invests in innovation for the long-term

GleSYS is an excellent example of smart, long-term thinking based on heat recovery

GleSYS is one of Sweden’s leading providers of cloud services and server hosting, and has two wholly owned date centers, one in Falkenberg, southwest Sweden, and one in Västberga in Stockholm. Since June 2017, GleSYS has supplied excess heat from its data center in Västberga to Stockholm Exergi’s district heating network. In the near future, excess heat from the data center will provide heat for more than 1,000 apartments annually.

”It has not felt good to see heat waft away into the air purely due to a lack of technology or interest in recovery. So this is a really exciting project that we genuinely believe in.”

Glenn Johansson, CEO

Simple business model
The business model and concept are simple. Two heat pumps are installed to cool the data center and deliver excess heat to the district heating network. Stockholm Exergi pays GleSYS for the heat it supplies, which in turn heats apartments in the surrounding area through the network.

“Even though this is a major investment for us, we expect to see a return within a year,” says Joakim Jarstorp.

Heating capacity is calculated to steadily increase to around 1MW, and as GleSYS expands, deliveries are expected to increase further. In addition to excess heat being recovered for the district heating network, GleSYS generates revenue, and contributes to reducing carbon dioxide emissions in Stockholm.

Installation of a new, unique heat pump
In co-operation with Stockholm Exergi, GleSYS has chosen to invest in a new type of heat pump that uses a highly environmentally friendly cooling agent, HFO, which is ultimately expected to replace R134a, the current industry standard. The installation is the first of its kind on the Swedish market, and comprises two Carrier heat pumps that generate higher temperatures more efficiently.

Bahnhof Thule – Profitable recovery with Open District Heating

Data center optimized for capital-efficient cooling and efficient heat recovery

The Internet supplier Bahnhof’s Thule facility in central Stockholm is probably Sweden’s most energy-efficient data center. With a cooling system that has been linked both to Stockholm Exergi’s district heating network and district cooling network, Bahnhof has created a technical solution that combines financial benefit with sustainability and very high operational reliability. The excess heat is recovered. At the same time the facility’s excess cooling capacity is used to meet the needs of other district cooling customers whenever Thule does not need the capacity.

Bahnhof Thule’s premises were initially built to house the insurance company Skandia’s data center. The place is the same, but the circumstances have changed a lot. The new data center requires far more energy than the facility that previously occupied the premises. Thule comprises three separate halls that have been built with energy efficiency and recovery as primary considerations.

Bahnhof has taken a conscious decision to build up expertise on how to design and build data centers, based on several new ideas concerning IT operations. One philosophy that is unusual in the industry is that Bahnhof likes to be close to its customers physically, with facilities in central locations in the middle of the city.

The heart of the cooling system at Thule is three heat pumps which are connected in series both on the cold and warm side. During normal operation the heat pumps produce both district heating and district cooling at the same time.

The compensation for the energy supplied to the district heating network varies according to the outdoor temperature. Deliveries to the district heating network therefore primarily take place when the outdoor temperature is less than 7 degrees Celsius, which in Stockholm is the case for around half the year.

The Thule facility has been dimensioned to take into account the long-term maximum need for cooling from the start. But the heat pumps can nevertheless be fully utilized from day one as the surplus capacity can be used for supplying cooling to the district cooling network. As the centers fill up with new customers and more equipment adds to the heat load, an ever increasing part of capacity will be used by Thule itself.

An important added value is that the district cooling network, together with the heat pump facility, act as two independent systems for cooling of Thule. The installation of the heat pumps has been made so that in an emergency they can be run in “island mode”, without connection to the district cooling system.