The vacant, unserviced 34 acre Korora block we found in 2016 was majority south facing steep coastal rainforest, but with a small area of north-east facing ex-banana plantation.
The natural, undeveloped condition of the site meant an off-grid solar energy system was our first choice. The rooftop PV solar optimises the solar harvest with a direct north orientation and an inclined flat roof area. The PV solar system design incorporating Lithium Ion battery storage, a backup genset and planning of appliances, utilised specialist off-grid modelling. An evacuated tube solar hot water system was selected, with instantaneous gas backup.
The initial civil works included the installation of 84,000L of in-ground load bearing concrete tanks to facilitate a level working platform and vehicle access. The 2/3 storey steel and timber framed BAL29 house is a separate structure, off the exposed edge of the tanks.
The house in plan is narrow, running along the steep contour over 3 storeys. The living area is located on the middle level at Ground floor and entry level, with the master bedroom on the Upper level and four bedrooms on the Lower Ground (LG) floor.
Thermal efficiency is achieved in a number of sustainable ways. The main roof form over the living areas slopes towards the north, with the roof kicked-up over the northern balcony to allow low winter sun to penetrate into the living space. The extensive eastern elevation/windows receive solar gains during winter mornings, while in summer, a direct cross-ventilation strategy utilises regularly occurring coastal seabreezes.
Large roof overhangs allow ventilation to be on-going through coastal rain events, and provides a large shade canopy for high hot summer sun. Passive cooling is also achieved by vent access to the cool air reservoir between the LG and the adjacent water tanks. During winter months, heating is by a slow combustion wood fire at the north end of the Ground floor living area, and uses natural convection to Upper floor and fan forced ducting to LG. The large simple roof form also captures all roof rainwater and feeds it directly into the water tanks, by a single oversized sculptural valley gutter and downpipe.
Locally sourced and milled hardwood, used as simple lapped vertical board cladding, compliments the lacquered rust red steel gutter/downpipe, and ties the house to the surrounding natural iron red soils. An internal planter box located high in the vaulted living area provides an air cleansing, oxygen producing ‘internal forest’, bringing nature into the otherwise human environment.
It is very satisfying to eliminate dependency on costly grid power/water/sewage. Although initial capital costs are higher in the short term, this house has been designed prioritising long term sustainable benefits for our family and future occupants. Fresh organic produce from our gardens is a more immediate benefit and will only be increased when many more and varied fruit and native trees are established using permaculture ideals, in our rich Coffs coast soils. A worm composting waste disposal system, gravity filtering grey-water and nutrients to the garden area, keeps the site self-contained.
We have enjoyed the spirit of experimentation in our sustainable house development, and where possible used innovative, enviro-friendly solutions when challenges have arisen during construction. In the first six months living in our sustainable house, its been a pleasure to experience the convenience and familiarity of the layout, and knowing we are living in a house which sits lightly in its natural environment.