E²volution - for a sustainable and cost-efficient system for modular construction of wooden multi-storey buildings
Although the forest is Finland’s most important natural resource and almost 60 million cubic meters of wood are harvested every year, concrete has so far been almost the only construction material used to build multi-storey buildings in the country. The city of Kouvola, whose economy has been suffering from the downturn in the paper industry, has recognised the potential for wood construction. In October 2010, the city announced the international two-stage competition ‘E2’ for planning teams from architects, engineers and specialist timber contractors. The task was to develop a system for timber construction that would use the design and construction properties of the material and thus demonstrate the ecological and economic benefits in comparison to concrete construction. Participants were asked to present the architectural diversity and flexibility of the system with the help of a pilot project on a riverside site.
E²volution impressed the jury
On 15 March 2011, the winners were officially announced in Kouvola, Finland. The timber competence team at Arup GmbH together with HHS Planer + Architekten and the timber construction team of Finnforest won first prize with their design E²volution. The team was led by Dr. Jan Wurm. The jury was impressed by the clarity and simplicity of the construction method developed by the team. "E²volution offers many extremely interesting starting points for the industrialised production of multi-storey timber developments.”
Systematic timber construction
The extraordinary strength and dimensional stability of the Finnforest Kerto® LVL (laminated veneer lumber) produced by Finnforest from local coniferous wood forms the basis of the system. With just three types of large-scale, prefabricated structural components, countless typologies and floor plans can be created. Wall, roof and floor elements consist of hollow boxes, which are fitted with thermal respectively sound insulation, fixings and membranes for water and air-tightness. The system is accomplished by external shear walls, which articulate the side elevations of the building and serve as supports for the freely configurable balconies, loggias and winter gardens.
The installation is sequenced by 7.5 m modules, that can be installed in a very time efficient way. The about 12 m long wall elements are installed first, and the floor and roof elements are hoisted in as the next stage, progressing from bottom to top, so that an entire weather-protected four-storey skeleton structure can be created in just a couple of days. For buildings over four storeys, the module can be stacked vertically.
The efficiency of the system in relation to energy efficiency, convenience and fire protection is achieved by consistent layering of the internal cladding elements, which are decoupled from the load-bearing elements.
Flexibility and versatility
The freely adjustable span of the ceiling elements of up to 12 m provides an extraordinary level of versatility over the entire life cycle of the building. The freedom to arrange and stack the wall panels as desired also ensures a high degree of design flexibility. Small flats for single people, as well as medium-sized and very large residential units, for example, for cross-generational living, were designed as part of the pilot project. Commercial uses are also catered for by multi-span systems.
The scenic location of the pilot project between the river, residential, industrial and mixed-use areas, as well as the adjacent four-lane street posed particular challenges with regard to urban development. The clear orientation of all flats towards the water, a public passage for the area, and above all the publicly accessible areas located directly next to the water have enriched the area and are of exceptional quality.
The E²volution system is designed to facilitate growth of wooden multi-storey construction as business. Only the large-scale primary load-bearing elements would be prefabricated during the pilot phase in the element factory, which is located 77 km away in Heinola, Finland. Despite the somewhat higher production costs, the construction costs would be competitive in comparison to the steel-concrete construction method long established in Finland due to shorter construction time. As the distribution of the system would be expanded in Nordic countries flexible elements such as exterior cladding, windows and installations could be integrated into the prefabrication process; this would further reduce costs by approximately 10%.
Headquartered in Kassel, HHS Planer + Architekten AG (HHS) employs over 30 people and has won numerous national and international awards for timber construction projects, for example, the ecology centre in Hamm and the retraining academy Mont-Cenis in Herne, both in Germany. The focus of HHS is on sustainable and energy efficient building design, the structural use of timber a key concern of its Sustainable Building Design Team.
Professor Manfred Hegger acts as the link between the office and the Energy Efficient Building Design Unit (‘ee’) at the Technical University of Darmstadt, Germany. The concepts developed and implemented for plus-energy buildings won the Solar Decathlon in 2007 and 2009.
Finnforest Merk belongs to Finnforest, which is part of the Metsäliitto Group, which combines responsible forestry with innovative technology to produce first-rate products and solutions from renewable northern wood in a sustainable manner.
Arup is well known around the world as an independent and interdisciplinary engineering and consulting company that supports and develops innovative concepts. The timber competence team at Arup GmbH in Berlin consists of experts in the disciplines of structural engineering, building physics, fire engineering, façade engineering and materials consulting.
In the E2 competition, there were two shared first prizes awarded. The Team Arup congratulates BIG/Copenhagen for winning the second first prize.
Images in Finnforest Image bank:
More information:
Arup GmbH, Berlin, Germany Tel. +49-30 885 9100
HHS Planer + Architekten AG, Kassel, Germany Tel. +49-561 930 940
Finnforest, Espoo, Finland, Design and Development Manager Jaakko Länsiluoto Tel. +358-1046 56421
Finnforest Merk GmbH, Aichach, Germany Tel. +49-8251 9080