GreenSmart Homes

"The Eco-Savannah"

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.

The design and construction of the home was an integrated process with the builder, Greg Byrne of Byrne Homes, consulting 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. Incorporating passive solar design techniques suited to the tropics, the house exemplifies how to make the most of cool breezes, while keeping heat out and daylight in.

DESIGN AND CONSTRUCTION INNOVATION

Passive Solar Design

The 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.

Outdoor Living

Located on the north-eastern corner of the home to capture cool north-easterly breezes, the 14m x 3.5m veranda 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.

Harness North-Easterly Breezes with Cross Ventilation

Cross ventilation requires openings on two sides of a room to accommodate air flow. From the back veranda, louvres, sliding glass doors and hopper windows that have a 100% opening capacity facing the north-easterly breeze. These windows direct breezes through the dining, living, kitchen and through the master bedroom areas. The breezeway from the front entry to the veranda, and louvres constructed in the master bedroom to the breezeway facilitate additional air flow. 

Strategic Shading

Shading is an important factor in reducing the amount of heat transfer to the house through windows, walls and the slab. With 900mm 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 shading screens were constructed on the western side of the verandah; both east and western sides of the carport; and the courtyard. These screens shade the slab where it would otherwise be exposed to the sun, to minimise heat transfer, without impeding breezes.

Windows on the western elevation were kept at a minimum, to avoid hot afternoon sun. The strategic shading to the east and west elevations of the verandah slab was chosen in consideration of the thermal mass effect, which is undesirable in Tropical Far North Queensland. A rainwater tank is also strategically placed on the western wall to give extra protection from the sun.

Future Proof

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 carport, master bedroom and living areas are in close proximity for accessibility convenience in later years.

MANAGEMENT OF ENERGY AND WATER

Energy and Greenhouse Efficient Water Heating

The house uses an Edwards 305 litre solar hot water, with the solar panels located on the roof. Although the initial cost of a solar hot water system is high compared with more conventional hot water systems, the cost saving made in the long term are far greater.

Solar Power

The solar power system for the remainder of the house is currently running on a 1kWhour 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 Conservation

The house has two rainwater tanks. For the house – a 10,500L tank, which supplies rainwater to the kitchen, and a 5,000L tank to water the garden and lawns. A bore has also been installed for gardening and lawns. The Metro tap ware from Irwell Taps installed throughout the house are 3-star, AAA rated.

SITE MANAGEMENT PRACTICES

The structural material used for the house is light-gauge steel framing, which leads to many benefits in terms of sustainable site management. These structural building components are pre-fabricated, eliminating surplus waste from off-cuts. This also means that there is less waste to remove, reducing greenhouse gas emissions from transport.

SELECTION OF MATERIALS

Structural Materials

Steel framing is the most recycled material in the world – it is 100% recyclable and steel products have a long life. By using steel products conserves other resources and reduce energy consumption that would otherwise be spent on manufacturing products with shorter life spans. Steel is re-useable and doesn't rot, split, warp, twist or burn. Many existing steel products can be reused without reprocessing, again saving on energy and resource use. The prefabricated components reduce the cost and impact of transportation – the more material a truck can carry to a building site, the fewer the total number of deliveries, saving on fuel and greenhouse gas emissions. High strength-to–weight ratios also mean that less material is required to construct the building, minimizing resource use. The steel framing used in the Eco-Savannah house is prefabricated, and prefabrication minimises wastage and creates safer building sites.

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, do not require maintenance or reapplication, reducing long-term maintenance costs.

Insulation – Reducing heat entry through roof and walls

The entire house is insulated throughout, to eliminate the need for artificial cooling. The external walls are insulated using a combination of sisalation and CSR Bradford batts. The roof is insulated using bonded wool insulation to the underside of the roof sheeting, and the western walls are further insulated with R2 wool batts for extra protection from the hot afternoon sun. Bradford Insulation glasswool is manufactured from a minimum of 50%, and up to 80%, recycled glass. Glasswool insulation products can save 12 times as much energy, during their first year in place, as the energy used to produce them, and are naturally fire resistant and remain so for the life of the product.

External Claddings, Doors and Windows

The cladding used throughout the house is a light weight cladding – a combination of Colorbond and James Hardie’s Linea chamferboard. Colourbond is easy to maintain, 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 to hold paint longer than timber, and it is moisture, termite and fire resistant for long life in Australia's harsh climate.

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.

Safe Floors

Vinyl floor covering is used throughout the house (with the exception of the bathrooms) making the floors slip resistant to guard against injuries.

Concrete

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. Veranda and patios are surfaced with Stylepave non-slip, hard-wearing, low maintenance material in ‘Rust’ a colour that matches the red-dirt of the Atherton Tablelands, to minimise the need for cleaning. 

INDOOR AIR QUALITY

Wattyl paints were used throughout the house in consideration of indoor air quality. The paint has no traditional paint odours, no ammonia, no formaldehyde and minimal Volatile Organic Compounds (VOCs). VOC’s are paints/finishes and adhesives, which can cause irritation and allergies, and impact poorly on your health.

COST EFFECTIVENESS

In total, the house cost approximately $355,000 when completed in 2007. Comparing this house to a similarly sized house, the owners have paid approximately 10% more in the short term, however, the cost savings from the features outline in this report, will save long-term expenses.

MARKET REPLICABILITY

The key aims of the project were achieved - keeping 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. Incorporating passive solar design techniques suited to the tropics, the house exemplifies how to make the most of cool breezes, while keeping heat out and daylight in. 

The Eco-Savannah home is not only sustainable and extremely energy efficient – it is also a beautiful, comfortable, practical family home. With a growing market with increasing awareness of sustainable housing this home exemplifies affordable sustainable housing.