CLT Passivehaus by Betti & Knut Architects

CLT Passivehaus extension in Balgowlah, New South Wales is made from pre-fabricated CLT (cross laminated timber) panels which were installed offsite and then installed with the help of a crane in a lightening quick 15 hours. Due to the efficiency of the CLT installation just one week later the extension was waterproof, insulated and airtight.

The form of the building was shaped by the client’s wish to retain established gum trees while maintaining privacy yet ensuring a connection to nature. Designed by architectural practice Betti & Knut to the Passivehaus standard the thermal efficiency of the building is designed to be comfortable year round without the need for artificial heating and minimal cooling. This is made possible by the high level of insulation, triple glazed timber windows and external shading.

Sustainability specs:
– Passivehaus certified, one of 25 in Australia
– All electric home
– Airtight design with automated ventilation system
– Low allergen, with no carpet used
– Cooled via cross flow ventilation and ceiling fans
– No heating is required
– Formaldehyde free joinery cabinets
– Untreated Blackbutt timber battens used for external facade, will natural grey over time
– Low VOC paints/sealer/varnish.
– Timber framed triple glazed windows and doors
– Hot water heat pump
– Efficient fixtures and fittings
– 2,000L rainwater storage tank
– Loads of natural light

This 2-storey extension to an existing house from the late 1920s was erected in a tight backyard. The budget of the house was very modest, though the quality needed to be decent to achieve a certified passivhaus rating. The entire CLT structure was prefabricated offsite, including the stair and cutouts for lighting, power and equipment.