Rainy Mountain Residence
Key Facts
• Design based on integrated approach to landscape, land use and ecology
• House designed to passively cool, with no mechanical cooling, which reduces demand on energy
• Intensive use of local materials and supplies
Project Data
Location: Kuranda, QLD, Australia
Year completed: 2013
Site Area: 32 Acres
OVERVIEW
Located in the Wet Tropics of Far North Queensland the home adjoins World Heritage rainforest and State Forest and is in close proximity to the Barron River.
The principle design concepts encapsulate a tropical lifestyle as well as celebrating and coexisting with the natural surrounding landscape. This is a comfortable, healthy and sustainable home environment. The owner builders intently chose local materials and suppliers.
The key features are a pavilion style house design that stands alone supported by energy, water and waste systems. There is minimal long term maintenance as it is resilient to tropical weather. The site use yields subsistent food production and protects and enhances the natural environment.
PLANNING AND MANAGEMENT
The owners had a strong desire to achieve a sustainable lifestyle for the life of the building and engaged an architect who had keen sustainability principles. An integrated approach to landscape, land use and ecology has been paramount in the design of this project.
Research was conducted with long term residents to understand factors and risks influencing tropical living. A weather station was installed to collect baseline weather data from the site prior to the design phase. Research into different sources of timber and their sustainable credentials including durability and suitability for tasks such as termite resistance was conducted.
A local structural engineering company with relevant knowledge for designing a project that is safe and resilient in a region prone to severe tropical weather events was engaged. The architects brief was documented identifying the requirement for the house design to compliment stand-alone energy and water systems.
SITE PLAN
The project site was formerly used as bullock grazing paddocks by local loggers. It had not been built on and had been previously cleared so did not require any additional land clearing.
The site is adjacent to World Heritage National Park and State Forest and lies within classified Cassowary habitat. Areas of the block are being progressively rehabilitated with native vegetation to provide food sources for Cassowaries and other local native species of birds and butterflies.
The house is sited to enjoy the views of the nearby ridgeline to the South and East and to take advantage of the breezes and ventilation. It is surrounded by natural mountain landforms which provide protection from extreme weather events.
The house site was prepared using a small 4x4 tractor. Minimal earthworks were required due to the construction footing method (steel posts).
The house site is an integral component of self-sufficiency goals and all topsoil was stripped, stockpiled and re-used in productive garden areas. A perimeter swale was constructed around the top side of the house to intercept wet season rainfall runoff and redirect it to minimise soil disturbance.
Site waste minimisation strategies include mulching and composting of green waste, the construction of evaporation trenches for effluent and feeding food scraps to chickens.
download PDF Air Flow Layout download PDF Air Flow in ElevationDESIGN
The house aspect was orientated to harness the prevailing winds to achieve ventilation goals. The house is high-set and built up-hill from a natural creek to enable cool air to flow towards the house in the still summer months.
The pavilion style home has 3 bedrooms divided into separate pavilions. The pavilion style supported a staged construction program enabling pavilions to be used for different functions throughout the construction phase. For example the laundry could function as a temporary kitchen. Also the pavilion style building can be easily added to at a later date if required.
The pavilion style is serviced by breezes moving around all four sides and underneath the building. They have double skinned roofs to maximise ventilation to cool the underside of the metal roof and remove the bulk of the heat radiating from the underside of the metal roof. Each pavilion has many ventilation openings to maximise the airflow through the room.
The design with large overhangs eliminates tropical rain and sun damage potential and achieves maximum ventilation to minimise mould growth for health reasons.
The building has been designed specifically for storm events. Eaves extend up to 1.5m protecting openings and outdoor areas. No gutters are on roofs not used for water harvesting. All glazing is toughened glass to withstand a category 4 cyclone event.
The design consciously enables easy access and inspection zones for termite activity. Steel posts assist this.
Most importantly, the house design is connected to the outdoors and has elements that promote a self-sufficient existence such as an orchard and vegetable garden.
MATERIALS
The owner builders prioritised a specification of high quality materials to achieve longevity and minimal ongoing maintenance. They used engineered timber to reduce timber milling and wastage. They also employed termite resistant Cyprus pine cladding because of its durability and termite resistance, and untreated cladding that will grey with age and not require maintenance using exterior paint products. The pavilions are timber and steel post structures with timber floors and metal roofs.
The design also compliments the use of green timber taking into account the expansion and contraction of timber framework throughout the wet and dry seasons including the floor duck boarding and overlapped cypress cladding. Bolts are accessible for periodic tightening of the structural frame.
Timber species were selected with durability in mind to ensure longevity of the structure. Wherever possible, locally-sourced materials were used, especially for the study and kitchen cabinetry and the front door.
No plaster based products are used due to their moisture absorbing properties. Products used internally allow for maximum expansion and contraction due to tropical moisture variations throughout the year.
ENERGY
The pavilion design maximises light and this ensures that daylight is sufficient for daytime tasks reducing the need to turn on lights during the day. To further reduce demand on electricity, the solar hot water system has a gas booster, the kitchen stove is gas and all appliances are selected based on their high energy rating.
No mechanical cooling is required as the building is designed to passively cool. This is achieved by positioning the house to gain maximum ventilation and each pavilion has many ventilation openings to maximise the airflow through rooms. Large overhangs provide plenty of shading from the hot summer sun.
After every effort to reduce reliance on electricity through design is achieved, then the renewable energy kicks in, to deliver a standalone energy system. Most energy is harvested from photo voltaic (PV) cells. A variable pitch wind turbine and a small scale pelton wheel (micro-hydro) are used as secondary power generators.
The design and installation of the energy systems have been specifically engineered to operate at an optimal level for long term reliability and cost efficiency. For example the batteries are predicted to last for 20 plus years. The energy system design has factored in future potential energy growth demand.
Finally, the energy system can be monitored using a smart Maximum Power Point Tracking (MPPT) as a solar charge controller.
WATER AND WASTE
There are nearby permanent creeks providing a constant fresh water supply although this is supplemented by rainwater harvesting from the roof as well as diverting it to gardens that support food production.
The water collected from the main pavilion roof surface runs into a 22,500 Litre storage tank.
The creek water that is used as a backup has a direct pressure water driven pump. It supplies water from the creek with no energy input apart from the passing water. This water is stored in a holding pond and can be used to drive a small scale Pelton wheel to generate power in times of insufficient solar radiation to supplement power supply.
Intercept swales also direct water towards the orchard and native gardens.
A separate 5000 Litre tank for firefighting activities is also on the site due to the proximity of services supported by the rural fire brigade.
PROJECT TEAM
Base building architect/ designer: Urakawa Jenkins Architects (Sydney) www.uj.net.au
Structural engineer: Colefax Rogers (Cairns)
Project managers: Hamish Jenkins (Owner) and Sarah Jenkins (Owner)
Energy efficiency rating consultant: ABSA Inc.
Builder: Owner builder is Hamish Jenkins
Other main contractors: Kuranda Electrics (Electrical), Mick Fuller Plumbing – Mareeba (Plumber), Cottons Wood Creations- Mareeba (internal fit-out)
