Flat-packed social housing on demand
Housing and flexibility Modular prefab timber systems Typological diversity and customisation
Ad hoc solutions in standardisation
Like many German cities, Bremen is confronted with an increasing housing shortage and a growing demand for affordable housing. In response to this, the largest Bremen housing association, GEWOBA, has prudently taken on a supplementary extension to their existing 45,000+ housing stock. In 2011, within the framework of the “Ungewöhnlich Wohnen” (Unusual Living) competition, five exemplary lots from a post-war housing area were chosen to investigate the adaptability of the area. The proposals considered contemporary demands for affordable and flexible housing that could offer manifold inhabitant configurations. These housing areas in the Gartendstadt Süd area of Neustadt Bremen offer generous green open spaces formed by uniform four-storeyed housing blocks.
The high adaptability and multiplicity of the modular prefab timber system makes the Bremen Cube (or Bremer Punkt in German) a pilot project for supplementary extensions to social housing on an urban scale.
The urban niches are activated by the integration of four-storey timber cubes. With a surface area of only 13.35 x 13.35 metres, the cube houses respond sensibly to the existing buildings, allowing the green open spaces on the estate to retain their appearance. The new buildings are designed with a modular timber prefab system. This allows flexible layout options for site-specific needs and responds to individual demands. The houses can adapt to differing apartment combinations, surface area, circulation, facade and building-form requirements.
With a 44-58 square metre living area (2-3 rooms), these smaller apartments manage to provide affordable housing with a higherthan-average standard of living, timber construction system, generous window openings, spacious private outdoor areas and an optimised southwest orientation. The new buildings upgrade the housing stock and local area, and afford existing tenants intergenerational equity, specifically for those requiring barrier-free design solutions.
Floor plan kit
The Bremen Cubes can accommodate up to 11 apartments per building. The floor plan kit showcases a catalogue of 22 apartment typologies, which can be combined with each other in over 60 variations.
The serial-building typology complements the existing housing with new flexible and barrier-free floor plans. The apartment sizes range from a one-room apartment of 30 square metres to a six-room apartment of 138 square metres.
Multiplicity and customisation of the apartment configurations ensure each site is able to offer an individual proposal to different user groups. All the apartments are barrier-free and two apartment typologies are fully accessible on wheelchair.
Timber modular system
The Bremen-Cubes are a modular construction system conceived and made up of predominantly prefabricated building elements. This type of construction system allows the realisation of differing floor plans in terms of size and organisation. The standardised system is suited to the erection of the building in the shortest possible time and with minimal construction site organisation and disturbance. The load-bearing outer wall elements feature a timber-frame system. The floor elements are in reinforced concrete or optimised Timber-Concrete Composite (TCC). The circulation areas are in reinforced concrete which strengthens the building’s horizontal loads and they serve as the primary escape route. This can be designed with either an inner core or an open circulation balcony core.
Timber construction materials are renewable and environmentally friendly, with considerably low “grey energy” consumption. In comparison to commonly used commercial construction methods, considerably less “grey energy” is consumed in the complete lifecycle process of timber: from raw material to material waste
disposal. The Timber-Concrete Composite floor system has a weight reduction of 50 per cent and reduces CO2 emissions by up to 90 per cent. The Bremen-Cube will receive a “NaWoh” certificate from the “Vereins zur Förderung der Nachhaltigkeit im Wohnungsbau e.V.” (German NGO for the advancement of housing sustainability). The assessment criteria consider socio-cultural factors, functionality and technical factors as well as life-cycle costs, long-term value, environmental compatibility and the healthimpact assessment.
The energy concept is based on a highly insulated building envelope which roughly correlates to a passive house standard, fulfilling the “KfW Effizienzhaus 55” standard. Energy and water usage is almost completely covered by the individual house’s solar panel facility and a heat pump with an accumulator. The ventilation system is designed over a central exhaust-air facility on the roof, which draws in clean air through the trickle vent system in the window frames. Domestic hot water is powered by local electric water heaters in each apartment, and underfloor heating with low supply temperatures helps to save additional energy while providing comfort. The Bremen-Cube fulfils the “KfW Effizienzhaus 55” standard with a yearly primary energy use at a maximum of 55 per cent of reference buildings from “EnEV 2014” (German energy conservation regulations).
Long-term development to serial production. Designing tailored solutions for different locations and demands by means of generating positive synergistic effects requires an extensive development phase. The experiences with the first realised prototypes serve the further development up to the serial maturity. Once this step is completed, the number of “unknown factors” is reduced. The building types are well-known to the authorities, the planning takes advantage of repetition and the construction process is going more smoothly.
The evaluation process continues until these synergy effects can be included.
(from the architect’s report)