Sustainable House Day, McElligott Ct, Horseshoe Bay, Magnetic Island, North Queensland

House Name: Backler Home

Construction type: Thick stone and concrete walls, curved skillion roof, raised timber floor, ideally oriented for daylighting and breeze access, and open plan for good cross ventilation. A well considered home designed for indoor-outdoor living and year around comfort in the tropics.

Climate Zone: Townsville is located in the Dry Tropics – there are two seasons: hot and humid (November to April), the wet season, and a warm to hot dry season with low humidity for the other half of the year.

Design/Build Process:  Owner Builder - new home (circa 2003)

Summary
In an unusual application of tropical design principles, this well considered home, provides excellent indoor / outdoor living and year around comfort in the tropics.
The homes uses the thermal mass of very thick stone and concrete walls in combination with a raised timber floor, high ceilings, a highly insulated curved skillion roof, and highly openable living spaces (inside and outside) ideally oriented to the north-east for natural daylighting and breeze access to provide coolness in summer and comfort in winter.
The household are participants in the Townsville Solar Cities Program whose goal is to reduce electricity consumption on Magnetic Island by 25% through education, behavioural change and the physical retrofitting of homes for energy efficiency. The Backler’s also opted to take up the program's offer to have a 1.5kW solar panel system installed on their roof – at no cost to the them, as part of an innovative third party ownership solar trial.

Background
Beginning in 2001, owners Kylie and Simon have gradually built a home where every part of it is their personal choice. The curved roof was designed to mimic the roof of their boat. The extensive use of very thick stone and concrete walls – an unusual choice in the tropics was a personal desire of Simon’s. The New Guinea Rosewood Kitchen selected for beauty and eco-sensitivity. And the list goes on.... And as owner builders, it’s been a labour of blood, sweat and tears (truly!) over many years whilst they’ve become parents, grown their family and worked to pay for the finishing touches.
The family enjoys the peace, solitude and security that the home provides and they relax at home in the company of their free roaming chickens and views of the bush out the back.

Orientation
Open plan living areas located along the eastern side of the home feature an almost continuous series of openings maximising access to breezes and natural daylighting.
The northern side of the building footprint is staggered to maximise the number of spaces that have direct access to a northern aspect and to prevailing north-easterly breezes.
The bedrooms are aligned along the western side of the home, but sheltered by the thick stone wall, they remain cool.

Roof
Creating an elegant silhouette, and setting it apart from the rest, the roof is one continuous arc, curved at 10 degrees over the entire home. The roof was constructed prior to the walls and is supported on steel posts and beams. Full (18 metre) lengths of roofing iron were used and shaped over the curved roof structure which was engineered and fabricated by CASA Engineering in Townsville who also make aircraft hangers.
The roof is fitted with a high (R3.0) level of insulation. Reflective (RFL) and bulk (thermal) insulation and a light grey colour for the roof sheeting was chosen to minimise the amount of heat transmitted through the roof into the house. The slightly curved ceilings are lined with fibre board.
The skillion style roof (ie no roofspace) is 400mm thick inside where (most of) the beams are concealed. Outside over the decks, the beams are exposed and the roof has a thickness of 300mm.

Walls
A very innovative feature of this home, is the use of 400mm thick stone and concrete walls both externally around the home and also internally - like a spine through the middle of the house. Despite the raised timber floors, all of these massive walls extend down to the ground and then deeper with their footings tapping into the relatively cool and constant temperature of the ground under the house. The result is a wall that maintains a very constant temperature, a consistently cool wall in summer which radiates ‘coolness’ and helps to provide a more stable indoor temperature year around.
The walls were built under the shade of the pre-constructed roof, using marine ply for formwork and backfilling behind the rock faced wall with a concrete slurry ! 240 tonnes of rock from the Pioneer Quarry in Townsville was trucked and ferried over to the island. Notably the rock was cheaper than the freight!
The internal walls in the bedrooms and study were rendered with a concrete slurry using a broom from a wheely bin!

As a result of the choice of walls, this home has a very grand, yet grounded, strong and secure feeling – even when almost the entire eastern side of the home is opened up to the outside.

Flooring
The house has a raised timber floor supported by steel posts and bearers.  The timber floor is mixed Australian plantation hardwoods.

Indoor Outdoor Living
Indoor / Outdoor Living is what this home is all about. With the living areas shallow and connecting through oversized openings to decks outside, and with a fabulous outlook to the bush beyond their property, the outdoor ‘lounge room’ on the deck, and the barbeque are used on a daily basis.

Openings
The openings used in the living spaces are oversized glass framed french doors and double bi-folding doors which open up to provide easy transitions between inside and outside living spaces, including the outside ‘lounge room’, as well as the barbeque area.
Windows in the bedrooms feature plain glass in modern timber framed casement windows which are positioned relatively high in the walls and under a 750mm eave to maximise the period of time when these windows are shaded to all except the late afternoon. Timber louvers were used in the bathrooms.
Porthole feature windows high the stone walls and framed by the curve of the roof above them were inspired by their boat.

Shading
Wider eaves, 750mm eaves are provided over the western wall and 600mm eaves over the southern stone walls. Large covered decks to the east of the living areas provide a high degree of shade to most of the east facing openings.

Convection
The ceilings are very high, to enable any warmer air to rise up well above people in the home. Air-movement is assisted by ceiling fans.

Timber
Beautiful New Guinea Rosewood – a Papua New Guinea hardwood timber that is selectively logged with portable sawmills in an environmentally friendly manner was used for the kitchen cabinetry.

Energy
Gas is used for cooking inside and the gas barbeque is used extensively outside.
As participants in the Magnetic Island Solar Cities Program, the cost of the Backler’s household’s electricity bill has been reduced by about 25%.
Physical changes made at the Backler’s home included hard wiring the washing machine, dryer, pool pump and air-conditioner into Tariff 33 (which enables the energy utility to cut off power to those appliances for typically up to 45 minutes during the times of the day when there is peak power usage. In return the cost of the electricity used by those appliances is charged to the homeowner at significantly cheaper rate than of the cost of standard Tariff 11 Electricity.)
50W halogen downlights were replaced with 35W compact fluorescent downlights, without the need to change the fittings. The lights are on multiple switches reducing the need to have them all on at once.
The household also has an ecoMeter which sits on their kitchen bench and shows how much energy they are using and also shows the total amount of energy used so far that day and in the previous week and the past month. Red or Green lights illuminate on the front to show whether the instantaneous use is higher or lower than average.
The home also has an energy efficient fridge and a relatively energy efficient bar fridge.

Renewable Energy
The family has leases space on their roof to Ergon Energy who have installed a 1.5kW solar panel (ie 12 panels)
As part of the Magnetic Island Solar Suburb project (a major initiative of the Townsville: Queensland Solar City Project), the Backlers opted to provide space on their roof to Ergon Energy who have installed a 1.5kW solar panel system (12 Kyocera solar panels) – at no cost to the household as part of an innovative third party ownership solar trial. A separate meter outside near their electricity box, show them how much energy their solar panels have generated from the sun and exported back to the grid.
The family also purchases $10 of renewable energy each quarter via their electricity bills and the Clean Energy from Ergon Energy program, which contributes towards offsetting some of their electricity consumption by the purchase of green power through their electricity supplier. 

Water
Tap and shower fittings are water efficient.
Greywater from the laundry is directed to the garden.
There is a plan to install a series of rainwater tanks when finances allow.

Garden
The garden, features a small area of lawn, a variety of kids play equipment, a variety of native plants and produce including avocado, native peanut, lemon and lime trees, tomatoes and herbs.
A small freeform concrete pool has been designed with child safety in mind, with one end deep and the other very shallow. The drop-off into the deeper water is delineated by large boulders.
The block backs onto a bush block featuring a variety of eucalypts and giant pandanus plants, providing a peaceful natural view from the back deck and living areas bringing wildlife into their backyard like wallabies.
  This home profile written by Sandy McCathie in collaboration with the owners. > >