re 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 Holzbau Renggli AG), is Switzerland’s first six-storey timber building, with a four-storey timber-framed construction on top of a concrete base. The project replaced an existing building and makes more intensive use of the 1600 sqm site. The new fire protection standard in Switzerland, introduced in January 2005, permits the construction of timber buildings of up to six storeys with a 60-minute fire-resistance capability. Each floor accommodates two spacious apartments of 149 sqm and 166 sqm. Cedar woods, anthracite coloured windows, fibre cement cladding (produced by Eternit) and corrugated sheet panels on the balconies characterize the building’s appearance (see Figure 10). The basement and ground floors are in concrete construction. From the first floor onwards only the central core, consisting of the staircase and the lift, are made from reinforced concrete, while the walls are in CLT construction and the ceilings are acoustically decoupled, beamed constructions. The timber-metal windows feature triple glazing. The comfort ventilation system, with waste-heat recovery, reduces heat loss through ventilation: subject to correct use by the inhabitants, an effective heat requirement ratio of just 20 kWh per square metre is achievable . A heat pump, with a geothermal probe, supports the heating and domestic warm water systems. Fine tuning of individual measures meant that the development was able to surpass the high criteria demanded by the stringent Swiss ‘Minergie’ standard.
4.8. CLT Building 8: The Forté Apartment Tower in Melbourne Docklands, Australia
Forté, the 10-storey timber residential building in Melbourne’s Docklands, is Australia’s first large CLT building and a landmark project for the whole timber industry in Australasia. 9 storeys in CLT sit on top of a concrete podium. The ground floor is used for retail space. The developer is Lend Lease, and its Australian CEO, Mark Menhinnitt, anticipates that ‘in future 30 to 50 per cent of their residential projects in the pipeline could be executed in CLT’; h