Eco Savannah House
• Designed by a Greensmart master builder and focused on low long term running costs
• Capital cost within range of comparable new houses in the Mareeba area
Location: Mareeba, QLD, Australia
Year completed: 2009
The Eco-Savannah house design focuses on ways in which a typical suburban house can be used to facilitate practical family living with energy, water and resource efficiency in both construction and use. Incorporating passive solar design techniques suited to the tropics, the house makes the most of cool breezes, while keeping heat out and daylight in.
PLANNING AND MANAGEMENT
The design and construction of the home was an integrated process with the builder who was involved in the project from early in the design process. One of the key aims of the project was to keep the capital cost of the house within the range of comparable new houses in the Mareeba area, while decreasing the long term running costs of the home.
The land is a typical suburban block and the house is oriented on the site for effective passive design.
This open-plan house is designed to maximise natural cooling through solar passive design, orientation, cross-ventilation, outdoor living, insulation, shading and careful selection of building materials to eliminate the need for artificial cooling.
Located on the north-eastern corner of the home to capture cool north-easterly breezes, the 14 metre x 3.5 metre verandah provides ample shaded cool outdoor living space. With accessible design to the kitchen and living areas, the positioning maximises the home’s capacity for convenience and comfort.
Cross ventilation requires openings on two sides of a room to accommodate air flow. From the back verandah, louvres and sliding glass doors have a 100% opening capacity and face the north-easterly breeze. These openings direct breezes through the dining, living, kitchen and master bedroom areas. The breezeway from the front entry to the verandah, and louvre windows in the master bedroom to the breezeway, facilitate additional air flow.
Shading is an important factor in reducing the amount of heat transfer to the house. With 900 mm eaves on all elevations, the house is protected from the tropical midday sun. These eaves are insulated and provide shading to external walls, doors and windows during the hottest times of the day.
Modwood is a reconstituted timber and plastic product and it is used here for shading screens placed on the western side of the verandah, the east and western sides of the carport and the courtyard. These screens deflect the sun and shade the slab where it would otherwise be exposed to the sun, without impeding breezes. The strategic shading to the east and west elevations of the verandah slab was chosen to stop any thermal mass effect, which is undesirable in the tropics.
Windows on the western elevation were kept to a minimum as glass transfers heat, especially from the hot afternoon sun. A rainwater tank is also strategically placed on the western wall to give extra protection from the sun.
To accommodate changing housing needs as the family grows and gets older, the house was constructed on a slab at ground level, making the house more ‘liveable’ for elderly occupants.
The structural material used for the house is prefabricated light-gauge steel framing, which leads to many benefits in terms of sustainable site management. These structural building components are prefabricated, eliminating surplus waste from off cuts. This also means that there is less waste to remove, reducing greenhouse gas emissions from transport.
Steel framing is 100% recyclable and steel products have a long life. The prefabricated components reduce the cost and impact of transportation. High strength-to-weight ratios also mean that less material is required to construct the building, minimising resource use.
Termi-mesh termite protection is used to protect the timber products in the house, including doors, architraves and skirting. Termi-mesh, as opposed to using chemical termite protectants, reduces long-term maintenance costs.
The entire house is insulated throughout to combat heat gain and reduce the need for artificial cooling. The external walls are insulated using a combination of sisalation and batts. The roof is insulated using bonded glass wool insulation to the underside of the roof sheeting, and the western walls are further insulated with R2 glass wool batts for extra protection from the hot afternoon sun.
The cladding used throughout the house is a light weight cladding – a combination of Colorbond and James Hardie’s Linea chamferboard. Colorbond is easy to maintain and is long lasting, durable, lightweight, thermally efficient, corrosion resistant, and resists chipping, flaking and blistering in normal weather conditions. James Hardie’s Linea chamferboard cladding is low maintenance - it resists rotting, shrinking and swelling, is moisture, termite and fire resistant.
A low VOC paint has also been used throughout.
All sliding glass windows and doors and louvres are tinted with Solis tint for extra protection from the harsh sun. The front and rear doors are made from recycled Red Cedar timber. The front gate is electric and automatic, making the house conveniently accessible and secure.
The driveway is exposed aggregate which is non-slip, formed in an hourglass shape, as opposed to a straight double-driveway, to conserve materials. The concrete located on the perimeter of the house is also exposed aggregate. Verandah and patios are surfaced with Stylepave non-slip, hard-wearing, low maintenance material in a rust colour that matches the red-dirt of the Atherton Tablelands, to minimise the need for cleaning.
The house uses an Edwards 305 litre solar hot water system with the solar panels located on the roof. Although the initial cost of a solar hot water system was high compared with more conventional hot water systems, the cost savings made in the long term are far greater.
The solar power system for the remainder of the house is currently running on a 1kWh solar power system. The system has a 2kW converter capacity so that in future, if the power needs of the house increase, more solar panels can be installed. All lighting used throughout the house is low voltage fluoro lighting.
WATER AND WASTE
The house has two rainwater tanks. The house has a 10,500 litre tank which supplies rainwater to the kitchen and a 5000 litre tank to water the garden and lawns. A bore has also been installed for gardening and lawns.
The Metro tapware from Irwell Taps installed throughout the house are 3-star, AAA rated.
Base building architect/ designer: Greg Byrne of Byrnes Homes
Other architect/ designer: Greg Byrne of Byrnes Homes
Builder: Greg Byrne of Byrnes Homes