Cederhusen / the Cedarhouses

Basic information

Project Title

Full project title

Two blocks of housing in solid wood, on top of an overdecking in the inner city of Stockholm

Project Description

Cederhusen demands attention with its 13 floors and 245 apartments spread across four buildings and two blocks. Its innovative use of 8800 m3 of Swedish timber makes it a standout solid wood project in a city center context. It sets an example for battling climate change through innovation and quality architecture. Inspired by Stockholm's 'stone town', its cedarshingles façade, clear order and structure make it a residential marvel and a captivating addition to the urban landscape.

Geographical Scope

Local

Project Region

Stockholm, Sweden, Sweden

Urban or rural issues

Mainly urban

Physical or other transformations

It refers to a physical transformation of the built environment (hard investment)

EU Programme or fund

Description of the project

Summary

Cederhusen is a tribute to craftsmanship, pride, and commitment. The project represents both tradition and innovation and has become an icon for sustainable urban architecture and groundbreaking timber construction. The project has been created with the entire city in mind, where high quality permeates every aspect, and with a strong focus on the human dimension in architecture. Folkhem has managed to realise what once seemed impossible, driven by the conviction that wood is the material of the future for modern and sustainable housing construction. Despite technical challenges and global trials during times of pandemic, war, climate change, and resource scarcity, Cederhusen stands ready to welcome its residents. It is a reminder that a strong will and conviction are the keys to overcoming obstacles. Consisting of four buildings across two blocks with 234 apartments, Cederhusen isn’t only an example of sustainable architecture but also an invitation to sensory experiences where scent, touch, and sight work together to awaken insights and knowledge in both residents and visitors. With its structure of 8,798 m3 of Swedish CLT, Cederhusen is a unique solid wood project in an urban environment. The location, situated above three of the E4 highway's tunnel roofs, required pioneering innovation and engineering. Its architecture is a modern interpretation of Stockholm's classical stone town architecture, with façades and details that embody the warm feel of wood. Cederhusen goes further by not standardising any details. Instead, every element, from mouldings to trim, has become part of a grandscale carpentry project. The project has become a model for sustainable construction. The CLT structure halves the carbon footprint, compared to a similar concrete house, and offers many practical advantages on the construction site. It has also contributed to increasing the industry's knowledge of wood as a high-performing building material. Fokhem only builts in wood due to co2

Key objectives for sustainability

Folkhem already made the decision in 2012 to build exclusively in wood. We did that mainly because of the climate issue. But experience also shows that wooden buildings mean both a better indoor environment, a better working environment, a reduced need for transport during the construction period and less impact on the surroundings. By building in wood, we save 60 percent CO2 in the construction phase and in the operating phase our houses approach the passive house standard. Wooden houses mean that we can build with our only renewable, non-toxic building material without additives. The Swedish forest produces wood equivalent to a solid wood project of around 60 apartments every eight minutes (equivalent to one of Cederhusen´s four houses). Because wooden houses are easy to assemble and require less foundation, we can also build more considerately to the site and minimize interventions in the natural environment. Wooden houses are simply perfect when we build in existing environments. Cederhusen is a project to specifically prove all these benefits according to co2-footprint in the choice of all materials, safe and healthy environment on the construction site, technical solutions in a wood construction to fulfill all regulations and recuirements. How to educate contractors the value of digital information and climate data and to create a demand on the market for these kind of projects to prove the business case of building in wood.

Key objectives for aesthetics and quality

Cederhusen are built in Hagastaden, a new district of Stockholm. The architectural object of the district is to mend the cityscape over large scale road and rail infrastructure connecting parts of the city that has been torned apart. High buildings results in high density. Light building technique has been a key factor in making it possible on top of the tunnels. Thus a wooden construction.

The buildings relate to the historical stone town of Stockholm even if they are built and clad in wood. By adopting classical expressions and give them a contemporary design Cederhusen is an example of how to use wood in an urban context. The warm earth colours in brick and plaster that dominate the facades in Stockholm gets an interpretation in red cedar shingles. Handcrafted execution has resulted in an extraordinary level detailing. The post and beam base of the building is clad with massive pinewood. The material of the building gives it an unusual and warm character with qualities for residents and flaneurs alike.

Key objectives for inclusion

There has been a process of high level involvement of all categories of technical consultants and experts because of the demands of the project. Folkhem is now having discussions regarding the process further of how to involve the LCA as a tool for decision through the whole process from politics, landallocations, deveopling concepts och buildings. How to make the carbon storage visible in the projects in order to create an additional business hence to financing.

Results in relation to category

The project has participated in a number of research/development projects. One was about the evaluation of different principles of slabs in CLT-buildings. Another about how to connect the BIM model with climate calculation software and the importance of EPD data on products. The analysis of the latter was followed up with companies in the supply chain to initiate their work to produce EPDs on their products. Another development project dealt with quality-assured information as a basis for climate calculations, where the focal point was a standardized language that can bridge the gap between the developer and the producing companies and the industry. Preferably at European level. Several degree projects have been written based on Cederhusen, including on construction economics, comparison between concrete and wood based on climate performance. Folkhem was part of the reference group at the Swedish Housing Authority in the work to produce the climate declaration law. On a weekly basis, Folkhem receives delegations from various other development companies who come and want to learn about wooden house construction on a large scale. Continuous measurements regarding the technical aspects have been carried out throughout the project in order to optimize the construction methodology.

How Citizens benefit

Cederhusen is built in a new district, a large infill project where two municipalities are built together and add 6,000 homes and 50,000 workplaces. According to the design program, it is to be built as a modern interpretation of the classic stone city, which is why all buildings are cladded with stone-based materials and glass. Folkhem has worked focused in dialogue with politicians and city officials as well as the firedepartment to enable an interpretation of the stone city in wood. The Cederhusen are therefore now completely cladded with wood on the outside in order to contribute to the urban environment with completely new qualities; a scent of wood, tactility and feeling of a living material that has a positive effect on people.
Since the start of developing the project in 2016, Folkhem has organized events for the public to inform about how and why it is important that we build the cities of the future out of wood. The industry's experts in the various technical areas of fire, construction, etc., as well as those who research the health aspect, have been invited there. The customers of apartments in the project had all got to visit the construction site and learned about how to build large apartment buildings in wood and that by asking for this type of building, you can contribute to climate change for an entire industry. Those who have since moved into the project have become fantastic ambassadors in many ways for the raising demand of future wooden construction.
Folkhem has also collaborated with the residents in making sustainability plans for the association and promoting a car-free lifestyle where there is an electric bicycle that is shared among other things.

Physical or other transformations

It refers to a physical transformation of the built environment (hard investment)

Innovative character

The Cederhusen are built on top of three tunnel roofs with governing requirements and limitations regarding weight, load removal and anchoring in the ground, which placed great demands on innovation to be able to enable construction on this site at all in accordance with the ambition of the detailed plan.
It was 1,5 years of investigations before it was clear that it was feasible to build on this site with these requirements at all. The fact that wood was then used made it possible to build all the floor plans that the regulation plan allowed. Building 11 floors in pure CLT was also groundbreaking when the project started its development in 2016 and required a completely different way of working in the project to solve the task. No ready-made principle solutions were available and the technical consultants had limited knowledge and experience. Folkhem got tovisit a number of reference projects in Sweden and out in Europe together with the project team to learn from how others had done.
Cladding the houses with wooden facades required good cooperation and dialogue with Stockholm's fire brigade in order to create security and knowledge about the technical aspects to meet the fire requirements. Among other things, the houses were to have two different colors, which is why Folkhem wanted to use both red and yellow cedar shingles on the facade. The yellow ones had not been used before in Europe, which is why Folkhem had to initiate and pay for fire tests to get the correct certification and classification of this product to be able to use it.
In order to find a contractor who was confident in building these houses, a collaboration was started early on with the contractor who built the first block. In the work with them, different principles for floor and wall constructions were investigated based on buildability and climate performance. When construction started, it was agreed to continuously measure and follow up and share information in order to optimize ongoing

Disciplines/knowledge reflected

The work on the project required close cooperation between the architects and the designer. Other technical experts were also involved as in all timber building projects.
In addition to that, we have had a continuous dialogue with the banks about the tools they have to redirect to sustainable investments. We have cooperated with the Fire Service in Stockholm to make the project possible. The majority of researchers and students have had access to the project for their work on specific issues. We have also worked closely with the entrepreneur to engage them in innovation-driven work.

Methodology used

Since the site's conditions were so special and demanding and there were no ready-made solutions for building in wood in this volume, Folkhem had to take an approach early on to drive the project and own the issues themselves to a greater extent, in order to take responsibility for making the project possible. Working in close collaboration with hand-picked people with experience, testing on a full scale, doing many more investigations than usual and continuously sharing knowledge and information has been crucial to success. Since this experience, Folkhem has set its work culture where every project must do a job in order to puch the positions forward in a specific question of development. The projects are made available for academic research to become a bridge between the academic world and reality. And Folkhem have understood the importance of not underestimating the need for information and knowledge to create commitment. We also trained in the format of material regarding co2-footprint per material in the second block and coolaborated with the contractor regarding strategic decisions when it came to choose between different products or materials

How stakeholders are engaged

Folkhem themselves have driven the incentive to build these two blocks in wood, as a prerequisite from the start. It has been a collaboration between Folkhem as the developer and the City of Stockholm to make the project possible, where they have been sensitive to how the requirement to build on the tunnel roofs had consequences for the project. Even since construction began, Municipality of Stockholm have been on site with their staff to learn from experiences from the project and gain knowledge about wooden construction in an urban environment. Folkhem has decided from the start to be transparent and that it is business critical to spread knowledge about large-scale wooden house construction in order to create more on demand policies, brave politics, more talented entrepreneurs, greater market demand, innovative developers who make demands. Therefore, over the years, Folkhem have received delegations from all over Sweden and now from all over the world to talk about the work on the project and show the construction site and the finished apartments. This has resulted in dialogue with the city's politicians and officials about how to allocate land, what can be demanded, what limit values can be set and more, in cooperation with property developers. Folkhem have been invited to speak at courses and seminars to raise the level of knowledge and create confidence in how to advance positions within industry standards and politics with regards to use more wood.. Folkhem have had a lot of meetings with the Stockholm Fire Brigade to agree on the technical details, how compliance with requirements should be followed up, what research is needed where there are ambiguities in legal requirements and risk analysis. Through the project, Folkhem has also participated as part of the reference group for the Housing Authority's work with the new climate declaration act to obtain reference values for houses built in wood.

Global challenges

The shift from concrete and fossil based material as solution towards more climatefriendly alternative such as wood. The methology of measuring of how to optimize the co2-footprint of what we built. How we built our future cities as carbon storages. The need of a standardized common language with unique identificators on product levels in order to create possibilities for circularity. The omportance of good architecyture as a sustainability factor. How we can built faster, easier with a light material. This should be beneficial in places where cities has been demolished.

Learning transferred to other parties

Folkhem's decided LCA process regarding how to continuously measure and follow up the climate footprint in the development of new building projects.
The principles regarding the technical solutions for large-scale wooden house construction without weather protection. Know-how to built on complicated sites with restrictions on loads and bad ground conditions.
The ongoing development work with quality-assured informationchain in projects based on standardized data and digital product codes, to enable traceability and reuse.
Folkhem participates as a partner in the WoodCircles project funded by the European Commission, which is about how we develop building systems in wood that can be dismantled and reused.
All experience from the project in total has great value based on what needs to be developed and optimized. Ensured in terms of both the supply chain, the political governance, the financing perspective and more