Perched on the eastern spur of Linden in the lower Blue Mountains sat a project home partially completed in 2003. The new owners, after suffering through several cold winters, decided that it was time to renovate the house to become a thermally comfortable family home.
The Blue Eco Homes’ design team suggested thinking about the site with the main principles of respecting the bushland at the core and re-using as much of the existing built form, services and structures as possible to reduce waste and manage costs. The new design incorporated the original building and two existing pavilions into one final structure, which followed the landform and a single eastern elevation where the sweeping views to the city skyline could be appreciated from multiple living spaces.
The close proximity of the natural bushland meant the external envelope had to be robust and non-combustible to meet the highest level of bushfire protection set in the original 2003 DA. As such the house is wrapped in zincalume cladding with bushfire-rated hardwood used as feature elements, along with BAL 40-rated windows. Many initiatives have been undertaken to ensure the house provides a high thermal performance envelope for its residents to cope with the extreme heat and cold of Linden. These include stripping back the old pavilions and completely re-insulating, using thermally broken window frames and lowering the glass-to-wall ratio. What is unique about this building is that it is an alteration to an existing building that greatly improves on its thermal performance from 2.9 Stars to 7.6 Stars, which reduces the peak demand, which, in turn, reduces the overall residential energy demand on peak days.
Where possible, the existing structure was retained and re-used, such as the concrete slab, rainwater tank, timber framing and structures. All other materials were disassembled and stored for re-use or recycling. All original cladding was sorted and stacked for re-use on non-visible cladding such as the soffits. All hardwood was sorted and stacked for re-use in decking, framing and light features. All cleared trees were mulched on-site and re-used for landscaping and remedial works. Excavated soil or other materials removed was recycled or re-used on site. Use of stone from on-site excavation was used in landscape design. Erosion was controlled by setting up earth mounds and silt fences, so the mounds would act as a detention system and not silt up new works or the adjoining properties. A radiant heat shield required by the Rural Fire Service was installed in a manner which allowed for natural flora and fauna to extend across the boundary.
The house is an off-grid potable and wastewater dwelling where all water used is captured off the roof into the existing concrete rainwater tank, re-used and treated on site with an aerated wastewater treatment system. There is a 3kW on-site photovoltaic system, with solar panels re-used from the original pavilions and an upgraded inverter with a grid inter-tie system. The inverter air-conditioning system was re-used from the original house, which is now zoned and can operate effectively because of the higher insulation in the home. Ceiling fans and cross ventilation are primarily used for comfort. The existing solar hot water system with panels on the new roof was re-used.
By re-using the embodied energy of the structures and selecting materials with low embodied energy such as timber as the primary framing, lining and joinery material, the project has a small footprint of new resources.
This re-design has resulted in a home with comfortable living, low environmental impact, reduced operating costs and an investment in lasting architecture. It is a worthy winner of the Excellence in Environmental Management award for 2018.
