The Woodcube, being part of the IBA 2013 (International Architecture Exhibition) in Hamburg, has 8 residential units with a net floor area of 900 m² on 5 floors.The exterior wall and ceiling elements are prefabricated from unbounded non-coated solid wood cross layered wooden boards which are connected with traditional beech wood rawl plugs.The inhabitant’s health benefits from this system because the usage of chemicals contained in coatings and glues can be avoided.By testing and evaluating the specific behavior of this wall system the fire protecting requirements for the building permit were achieved without the installation of a sprinkler system or a stand pipe.
A unique wall system
Local, cut down with special attention for the right time and carefully dried timber is being used for the wall elements.The horizontally, vertically and diagonally layered boards are connected solely with traditional beech wood rawl plugs into 32cm thick wall elements.The exterior wall elements are loadbearing and serve as an insulation layer and also for fire protection.To enhance the insulation performance of the wall system a 4 cm thick layer of wood soft fiberboard was added into the layers of the wall elements.A special pattern engraved into the surface of the layered boards creates enclosed air cavities in the wall elements. This 2 measures improve the thermal conductivity of soft wood to 0,078W/mK.
It was possible to manufacture the entire exterior wall system without adding glue into the materials.The Woodcube achieves a the energy standard of a passive house.For the first time it was achieved to build a category 4 building (Germany) in wood without adding an additional fire protection layer of a non-burning material.By using horizontal wooden barriers in the substructure of the wood cladding the vertical fire spreading can be confined. Hygrothermal simulations proved the use of the best cladding profile and façade subconstruction
Building biology / Biorecyclingpotential
The consistent abandonment of contaminating construction chemicals continues in the interior of the building. All construction materials were examined by building biologists to exclude health hazardous materials and to be harmless to the environment. All essential materials used are bio-recyclable. This means that materials are not just recyclable; they are biodegradable not leaving behind undegradable waste for future generations.
In general a high amount of natural construction material is being used to minimize the VOC contamination andother toxic materials in the interior spaces.All construction work in and outside the building were enforced by strict building biology regulations.
Neutral carbon footprint
Even though the basement and the staircase were built in reinforced concrete a carbon footprint calculation by INA / TU Darmstadt proves that the Woodcube is the first building with a neutral carbon footprint upon completion.Against the background, that building a standard passive house uses a multiple amount of annual energy needed for heating, this reduction of the embodied energy is an essential advantage of solid wood construction. The lack of attention towards this criterion becomes apparent when noticing that no subsidy requirements for building demand the reduction of embodied energy .