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’; he noted ‘this project will unlock a new era for sustainable development by offering a viable alternative to traditional construction options, which are carbon intensive’ . He expects CLT construction to be used in other applications, including educational, community and commercial buildings.
The advantages of CLT are particularly relevant to the Docklands location and the Victoria Harbour precinct, as its reduced weight generated substantial below-ground savings and the fast build suited the compact site. Forté aims to be Australia’s first five-star GreenStar as-built certified residential building. According to the developers, by using CLT, Forté will reduce carbon emissions by more than 1400 tonnes of CO2, compared with building in concrete and steel. The advantages are likely to continue for residents too: the 23 apartments require 25 per cent less energy to heat and cool than a similar apartment built in reinforced concrete; they note that the building will be carbon neutral for at least 10 years.
Construction of the building took only from February to October 2012, constructed from 760 CLT panels, which were shipped from Austria to Australia in 25 containers (panel length limited to 12 metres due to container size). In the assembly process, around 25 panels per day were put in place. However, only few timber surface is exposed in the final building, reduced to one ‘feature wall’ per unit. An earlier design option proposed the entire building to be wood clad, but ‘it was then decided to reduce the timber aesthetic, to avoid marketing risks’ . The developer decided on ‘a more ordinary façade to have a building not completely out of the ordinary.’ The developer also decided that ‘the building would be fully sprinklered to make it look safe and simplify the approval process, although this measure was not requested by the Fire Department’ . (See Figure 11 a and b).
5. What Architects and Developers Think About CLT Construction
There is still a lack of knowledge within the architectural design community about CLT 