The Woodhouse

The Woodhouse

In Rieselfeld, a city district with various residential possibilities, the Wood House that was invested, planned and constructed by Frey Architekten Group, Germany, stands out among others.

As a pioneer project for ecological buildings, the Wood House not only fulfills the standards for low-energy passive house, but also exemplifies high requirements in applied building technologies, which includes large planted area creating on the rooftop, decentralized ventilation with heat recovery function, photovoltaics, solar water heating and warm supply by wood pellet fuels. Owing to the innovative exploration in the Project “Wood House”, the Frey Architekten Group won the “Best Practice Award” in the field of sustainable building and urban planning with this project and was received by the former German president Mr. Horst Köhler.

Architecture & Design

The Wood House is a four-storey residential building. Outside of the construction volume is a self-supporting structure in steel – a few steel beams supporting the balcony of each storey and photovoltaic canopies. The northern façade is facing the street, the southern a garden and the eastern is connected with other buildings. The entrance of an underground parking lot is located in the western part, which creates a wide lighting space. In this way, three of the façades are set with veranda-like installations that enhance the communication with the surroundings. 

The Wood House includes as many as 11 different room layouts to meet the needs of different groups. At the eastern and western end of each storey are spacious apartments, connecting the southern and northern façades. Besides, all residential units are connected in series by a vertical transportation core. 

The whole building is barrier-free and three apartments within are rented by a local social welfare organization for the benefit of those residents in need.

Wooden Structure 

The Wood House characterizes itself mostly by its main structure that is constructed by prefabricated wood artifacts. The selection process for the wood is in accordance with the local construction traditions and also calls for a familiarity of architects with material qualities. The prefabrication of materials on the other hand lower the construction costs and shorten the construction period.

Considering the life cycle of a building, wood is as a material carbon neutralized and environmentally friendly. Apart from the basement and core tube, other bearing structures are of wood, in which the floor slab is of cross-laminated timber and the outer wall the solid wood with pattern of denticulate stripes. 

Cross-laminated timber is an innovative type of building material. The manufacturing process goes as the following: Kiln dried (with the parameter humidity controlled at around 12 %) and finger-jointed cedar wood cutting into battens, lumber grouping and planning, adhesive application and panels pressing with the hydraulic or vacuum press machine. Such manufactured is cross-laminated timber, whose size and thickness can be adjusted practically. Compared with the regular wood components such as beam and column, whose capacity of load bearing is one-directional, the cross-laminated timber can achieve that in different directions, thus possessing the strength like reinforced concrete. In regards to the earthquake resistance, the cross-laminated timber performs even better, according to the test.

Such a choice of material excludes the horizontal timber partition that is considered as a more modernized building material, in order to avoid an accumulation of rainwater on the horizontal texture of timber, which further creates a humid condition where the timber would easily get rotted. The solid wood on the façade of the Wood House preserves the original natural texture of wood and moreover refrains from the use of protective lacquer, which decreases the burden on the environment. 

The periphery structure of the Wood House including the external wall, windows and bottom plate is equipped with successive thermal insulating layer and inner liners and thus has a low heat transfer coefficient, which fulfills the standards of the passive house.

Comparing to the buildings in reinforced concrete with the same volume, the Wood House performs prominently in regards of the CO2 emission owing to its wooden structure. As the following chart reveals, the former has a CO2 emission as much as 206 tons during its whole life cycle, when the Wood House adds no more emission to the environment and even absorbs 85 tons of it. 

Before the Wood House, the projects concerning large residential buildings with wooden structure normally would not be officially approved at the application stage under the current regulations, which concerns about the hidden danger out of the inflammability of the material. In cooperation with relevant institutions in Brunswick und Leipzig, The Frey Architekten Group lead a series of researches and experiments on the fireproof and fire resistance of wood as building material and finally adopted the cross-laminated timber to realize a wooden structure with relatively large scale. This application leads to a success and declares the feasibility of the new type of building material. 

Apart from the wooden volume, the building comprises cold-constructed steel structure. The Frey Architekten Group draws inspiration from the overhanging eave of the traditional wooden farmhouses in the Black Forest region and employs photovoltaic canopies to imitate such a structure, which results in various advantages: the south-facing installations maximize the efficiency of electricity generalization, protect the outer wall from the bad weather and act as a shelter in the roof garden.

The tilting steel columns symbolize a forest: some climbing plant grows along the columns, creating scenery for the façade and adjusting the microclimate. All balconies, whose load is carried by these steel columns, are connected to the main structure merely with limited number of pitting anchor bolts, decreasing the influence of thermal bridge on the interior. It minimalizes the energy consumption for heating in the building, which is a vital requirement for passive house.

Heating Equipment

The heating system of the Wood House accords with the various needs of different residential units and adopts the pattern of centralized heating supply and dispersed ventilation. 

The source of centralized heating is the wood pellet fuel, which comes originally from the sawn or compacting wood. As an ecological fuel, it contains energy of 4,7 -5,2 megawatt hour per ton, has an combustion efficiency of above 85% and meanwhile achieves a low emission of NOx, SOx and volatile organic compounds. The boiler by the wood pellet fuel further provides warm recycled water for the floor heating system in each unit.

The outer walls of the main functional rooms in each residential unit such as the salon and the living room are equipped with small ventilation facility that conveys clean fresh air to the interior. The ventilation facility is also installed with heat exchange equipment, retaining the heat inside and alleviating the energy consumption for heating. 

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  • Typology:
  • Residential-/Commercial Buildings

  • Client:
  • Freie Liegenschaftsverwaltung GmbH
  • Location:
  • Freiburg, Germany
  • Gross floor area:
  • 1400㎡