Residential building company Cosmopolitan Living says it has designed and built a 9-star energy-rated house on a project home budget without compromising the design, construction or liveability.

The 9-star energy rating was provided on the building’s completion by the Association of Building Sustainability Assessors (ABSA).

The result of an collaboration between Cosmopolitan Living and Boral, the new three-bedroom Newport 160 display home is now open for inspection at Waterford, in south-east Queensland.

The materials selection involved the minimal use of lightweight materials with building density and thermal mass provided by Boral clay bricks, concrete roof tiles and concrete blocks.

While the minimum energy efficiency rating for new homes in Queensland is a 6-star, the Newport design was upgraded during the planning stages to a 9-star plus. The decision to upgrade did not affect the original design elements in the home.

According to the builders, a key consideration in energy efficient material selection was whether it fitted in to the normal building process without increasing the cost of construction.

“A good example is the inclusion of glazed Low E Dowell windows to reduce heat absorption, the installation process is the same but the glass is better quality,” according to Chris Drakos, Cosmopolitan Living business development manager.

For roof and timber wall insulation, Cosmopolitan Living also changed to AirCell, which has a higher energy rating than the typical foil backed type, without affecting the building process.

A switch from standard brick veneer walls to high-density, double-brick cavity walls for west-facing dining and living room areas, will delay heat transfer into the house and thereby reduce the need for artificial cooling.

In the hallway, Boral was also able to accommodate a 70mm thick brick wall within the original timber frame work design. This insulated wall will help reduce heat transfer from the sun during the day.

The main ingredient in creating an energy efficient roof and ceiling system is careful selection of the roof tiles. For this, a light coloured concrete roof tile in the Boral Windsor Range was used.

According to Drakos, concrete roof tiles offer not only thermal benefits, but are also an affordable option with the added advantages of offering acoustic insulation and are low-maintenance.

Cosmopolitan Group director Chris Condoleon said Australia’s ageing demographic, and decreasing affordability for first-home buyers convinced them there was a gap in the housing market.

“We thought there existed a market for a type of dwelling that meets the needs of a broad cross section of Australians,” he said.

According to Condoleon, the Newport house appeals to both ends of the market. “It’s suited to empty nesters, who require a low maintenance home that can be cheaply adapted as their needs change and it’s also an attractive entry level home for first-home buyers.

“From the perspective of the design concept, energy efficiency and affordability, we believe it’s the most innovative in the marketplace. The private residential market has been calling for this type of home for some time now,” he said.

Boral Clay & Concrete regional general manager Ben Sawley said: “Working with Cosmopolitan Living has meant Boral had input into selecting the right products to meet energy and cost objectives and provided the design for the paving and retaining wall components of the house.”

Boral Designer Block replaced the original render design on the façade, providing texture and colour elements for the entrance area.

“This was a very good and unique find for this project and we believe it’s something that’s quite new to the domestic construction market,” Drakos said.

In terms of materials, Drakos added, the products used were mostly standard with no one off products.

According to Condolean, the liveability of the house is extremely high with lots of natural light thanks to the higher ratio between floor area to window size which lets in more light.

The higher energy efficiency criteria is also attributed to cross ventilation from the placement of windows in direct line of sight, which creates a breeze and improves the thermal qualities of the home, while also enhancing comfort for residents.

The 9-star rating reflects only the house structure and doesn’t take in to account energy savings and sustainable techniques in external areas, such as the permeable paving, retaining walls and low maintenance and low water garden. Not many display home designs take these initiatives beyond the walls of the home to make it a truly energy saving design.

David Wheeldon

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