Environmental community

A district near Stockholm’s city centre has set a high benchmark for sustainability in new urban developments

In bidding for the 2004 Olympic Games, the Swedish capital city of Stockholm planned to build an amazing new district to function as its Olympic Village. The district, called Hammarby Sjöstad, would stand up as an excellent example of an environmentally friendly community.

Built on a former industrial brownfield site, the district
is focused on Hammarby Lake

But when the 2004 Games were eventually awarded to Athens, the momentum for change had already been established – and so it was agreed to proceed with the project.

“The detailed plan for the city area changed because we did not have to build different arenas for the games. But the environmental programme remained intact,” says Erik Freudenthal from the project’s education centre.

Built on a former industrial brownfield site, south of Stockholm city centre, the site is focused on Hammarby Lake. “Sjö” is Swedish for “lake” – “Sjöstad” literally translating as “city surrounding Hammarby Lake”. The aim of the project was to expand the inner city and make a feature of the water, with the lake functioning as the district’s “blue eye”.

Containing 9,000 apartments providing housing for 20,000 people, the 200 hectare site also features 200,000 sq m of commercial floor space, attracting up to another 10,000 people to work in the area.

The concept was born in the 1990s and the project is now approximately 50 per cent completed, with all sub-districts set to be ready by 2015.

With water as the central theme, it was seen as an opportunity to take a tired, old industrial port and transform it into a modern, high-tech city district with a huge emphasis on sustainability.

At the time of Stockholm bidding for the Olympic Games, sustainability was its unique selling point. The district’s environmental plans are based around a cyclical set of pioneering principles called “The Hammarby Model”, whereby as much is recycled as possible, where waste gets turned back into energy for homes, and where water is carefully managed.

Stormwater passes in this canal and returns to the lake

The model was developed jointly between Birka Energy, Stockholm Water Company and the City of Stockholm Waste Management Bureau. The aim of the project was to be twice as environmentally effective as normal new build projects in the inner city – and this by a nation renowned for its environmental efforts for many years.

Here’s how the Hammarby Model works: Sewage water gets cleaned and purified at a nearby treatment plant and recycled into natural gas, which is used as an energy source for the Sjöstad. This purification process produces heat that is recycled for use at a district-heating unit. The area also has its own pilot sewage treatment centre that recycles nutrients from sewage for use on agricultural land.

Surface water gets cleaned locally and any combustible waste is recycled into heat energy for use in apartments. Each of the apartment blocks has recycling facilities. Biodegradable waste is composted nearby, and it is then bought by a soil company who make it available to buy in supermarkets and garden centres.

The district has a central building known as GlashusEtt (the Glass House) that functions as an education centre for informing citizens about the many ways in which Hammarby Sjöstad is a sustainable community, and tells them how they can help make it work. Here, Stockholm Water, the city’s street cleaning department, and energy company Fortum can showcase the range of technical solutions used across the district. The centre also has two conference rooms, one seating 60 people, as well as a smaller discussion room for around 10 people.

The Glass House centre cost GBP 2m to build, with costs underwritten by the City of Stockholm and approximately one third of investment funded by a Local Investment Programme grant. Ongoing annual funding for the centre – approximately GBP 100,000 – is split equally between Stockholm Water, Fortum and the City of Stockholm’s land development bureau.

A model of the district shows how there is an overall
masterplan for the sub-districts

The design of Hammarby Sjöstad is intentionally urban, despite being some way from what is traditionally thought of as the centre of Stockholm. It follows standards for the inner city in terms of street width (18m), block sizes (70x100m), density and land use. This city style has been blended with a new architectural style that promotes sustainability technology, and makes the most of its waterside locale.

In keeping with modern architectural principles there is an emphasis on maximising light and views of water and green spaces. This is achieved by using glass as a core building material.

A network of parks, green spaces and public walkways run through the district and wherever possible the natural landscape has been preserved, even providing inspiration for the development. Reeds and rushes growing around the outskirts of the lake have been kept, with secluded footpaths laid amongst them.

Restricted building depths, set back penthouses, multi-level apartments, generous balconies and terraces, large windows, flat roofs and pale plastered facades facing the water exemplify the application of a modernistic architectural agenda.

Public transport services are excellent, with a new road and tram infrastructure at the core. Hammarby Sjöstad’s four tram stops link the district to the city’s underground network. And plans are in the pipeline to extend the tram eastwards so that it links into Stockholm’s main tram network. There is also a free ferry link across the lake, running at regular intervals from early morning until midnight. Residents also have access to a car pool. There are between 20-25 cars in the pool and thus far 270 residents (eight per cent) have joined the scheme.

The area is divided up into 12 sub-districts that are gradually being completed in a series of development phases. Six have been finished so far as the project keeps on track to be completed by 2015.

The Glass House centre cost GBP 2m to build, with
costs underwritten by the City of Stockholm

A system of “parallel sketches” has been used as part of the process of completing a detailed masterplan for each district. The City Planning Bureau chooses three or four private sector architects/planners who are appointed to “test” the masterplan and draw up more detailed proposals for the sub-district.

There is an emphasis on choosing young, up-and-coming architects with fresh ideas. The city then evaluates their designs and ideas and incorporates the best aspects of each to end up with an agreed detailed masterplan. The overall aim is to arrive at a district that features rich architectural diversity under a unifying code.

The masterplan ensures that there is a strong network of streets and public spaces, with a rounded and sustainable mix of uses and an excellent variety of community facilities.

With the masterplan now a decade old, its successes are clearly visible in the sub-districts that have been completed so far. Credit must go to the project team who have acted as “keepers of the masterplan”, ensuring that core principles are preserved despite whatever market pressures or trends come along.

The idea all along was to create a high-density urban district that can sustain a range of shops and services. To help achieve this, a brilliant planning policy has been put in place whereby financial incentives are provided to encourage shops and services to open before the market has fully formed.

The area’s biggest strength though is its sustainability. One particularly interesting aspect of this is the district’s waste handling system.

The system was supplied by Envac, a global leader in underground automated waste collection systems. An underground system was chosen to minimise traffic in the district and to facilitate waste separation for residents and commerce.

The company’s high-tech methods use a fully enclosed vacuum system, which means nobody needs to come into contact with refuse sacks or containers – eliminating foul-smelling rubbish bins at street level. Waste is just thrown into a normal inlet with one inlet for each fraction (incinerable and organic waste).

Envac’s technology has helped developers to be successful in reaching the target of a 60 per cent reduction of heavy traffic in the area. Once the district is completed, the system will have a central position in Hammarby Sjöstad’s waste handling, processing the majority of the fractions.

The system consists of a number of collection points, linked together by pipework that transports the waste to a central collection station. When a refuse bag is deposited into an inlet, it gets stored temporarily in a chute on top of a discharge valve. All full inlets connected to the collection station are automatically emptied at regular intervals. The control system switches on the fans and a vacuum is created in the network of pipes.

One by one, the discharge valves below each chute are opened and the refuse bags fall into the network of pipes and down to the collection stations. Refuse enters the stations via a cyclone that separates the refuse from the air. Refuse then falls into a compactor, which compresses the rubbish into a sealed container. The transport air is then passed through dust and deodorant filters and a silencer on its way out.

“The tank serves as an intermediary collection space until the waste is collected by suction trucks,” say Envac. These trucks then transport the refuse to incineration facilities, composting plants or land fills.

The system has a capacity of 2,400 apartments and deals with 811 tonnes of refuse a year. The whole operation involves 270 inlets and the same number of storage tanks – all connected up by 3,800m of piping.

The district previously housed artisans’ workshops and small industries, which left behind a great deal of pollution, leaving the city’s Environment and Health Administration to clear and decontaminate the area.

Apart from the use of sustainable and eco-friendly construction materials, and the impressive waste collection system, rainwater from the streets is collected, purified and then released into the nearby lake Hammarby Sjö, rather than ending up in the sewer system and burdening the wastewater plant.

“Stormwater from the buildings is discharged into the canal and the stormwater from the streets is taken care of in a sand filter or a wetland where the water evaporates through the land down to groundwater,” says Freudenthal.

Via solar panels on some of the roofs, the light energy of the sun is harnessed into electric energy to light stairways and satisfy the inhabitants’ hot water requirements.

Additionally, biogas is produced in the estate’s waste treatment plant from the digestion of organic waste from wastewater. Most of the biogas is currently used as fuel in eco-friendly cars and buses.

“When you treat the waste water you get, as a result, sludge,” says Freudenthal. “You put the sludge into large tanks and the biogas is then produced in an oxygen-free environment. Then you have to clean it through water and you get methane gas (biogas)”.

Monitoring and verification systems will be established on several levels to evaluate the success of the district. Due to the importance of Life Cycle Analysis for the development and evaluation phase of the Hammarby Sjöstad Project, management teams have devised a unique metric to help evaluate all activities.

The Environmental Load Profile will evaluate different scenarios regarding design of technical infrastructure (water, heating, cooling, sewerage, and waste) as well as the lifestyles of the residents.

The Sewage Treatment Plant Steering Committee has taken steps to build a monitoring station to measure the composition of the wastewater at the local sewage treatment plant. In addition, teams will monitor the residents’ consumption patterns for energy and water by using an individual measuring system for each apartment.

This remarkable district stands as a beacon to future city developments. If you want your city development to be sustainable, you could learn a thing or two from Hammarby Sjöstad.