iscussed and developed alternatives and shared specific knowledge on timber construction. In April 2012, the author met with residents to discuss their lifestyle choices and reasons to decide for living in the building. The findings are similar to the Norwegian case: the occupants are very much aware of the ‘green’ construction method; they like the idea that the building materials are natural, and are conscious of the sustainability aspects of the buildings.
4.5. CLT Building 5: Wagramerstrasse Public Housing, Vienna
This is Austria’s highest residential building constructed with CLT systems: 101 apartments in a 7-storey slab along Wagramerstrasse and three 3-storey fingers forming courtyards. Six storeys of CLT sit on top of a concrete podium . The solution is the outcome of a 2009 design competition organized by the City of Vienna. The build is a composite structure of concrete cores with the CLT system; engineer Wolfgang Winter predicts that ‘most large-scale multistorey timber buildings in future will be hybrid structures, where sound insulation is typically added via the use of concrete or screed’ . The 2400 m3 timber structure stores around 2400 tonnes of CO2, which equals the annual emissions of 1630 cars. The panels were manufactured by Binderholz Bausysteme and the project is completed in February 2013. The apartments are 2, 3 and 4 bedroom units of 60 to 105 sqm in size; some are maisonettes.
4.6. CLT Building 6: The ‘e3’ Multi-Apartment Building at 3 Esmarchstrasse, in Berlin Prenzlauer Berg
The e3 apartment building, designed by architects Kaden and Klingbeil was only possible as a special exception to Berlin’s stringent building code. It is a seven-storey timber frame building, something still uncommon in ‘stone-built Berlin’; a hybrid construction using CLT panels for walls and glue-lam elements (the primary structural floor panels are in ‘Brettstapel’ method). Today, the majority of large multistorey timber structures are composites of different engineered timber systems . The wooden floor slabs are packaged in fire-retardant gypsum fibreboard, as are the solid wooden walls. The wood-concrete composite ceilings feature, on their underside, timber planks covered with a fire prevention glaze. Tenants have laid flooring of their choice on the concrete upper side. Apart from two concrete cores, which run the entire length of the building for stability and installation, the apartment layouts are flexible and can be subdivided and arranged as desired. The results are loft-like spaces and small ateliers, built in an extremely short construction phase. The gross square metre prices of 1900 to 2400 Euros, which vary from floor to floor within the building, are comparable to conventional developer projects in concrete frame. Close cooperation with the fire brigade was necessary to obtain permission; the building’s design and fire safety measures (such as short escape routes) proved sufficient to satisfy the fire brigade: a free-standing external staircase made of concrete, positioned along the fire wall of the adjacent building—as it can neither catch fire nor fill with smoke. The external façade is plastered and the white rendering makes it look like conventional urban infill, not recognisable as a wooden building. The building has high-quality insulation and maximum annual energy consumption is only 40 kWh per square metre. In Germany, the trend towards timber-framed and CLT buildings, advanced years ago by the Bavarian State Building Authority’s research, pilot projects and amended building regulations, has now arrived in densely populated inner cities (such as Berlin) in the form of infill prototypes. Whether or not this sustainable style of building will become more widespread will also depend on the wider acceptance and the willingness of relevant authorities to be flexible in approving the new construction methods.
4.7. CLT Building 7: The Holzhausen Apartment Building in Steinhausen, Switzerland
This apartment building designed by architects Scheitlin, Syfrig and Partner (in collaboration with manufacturer 