Local sourcing was one of the key strategies used by Defence Housing Australia to ensure its recently completed Prince’s Terrace project in Adelaide went above and beyond on sustainability.
The development, comprising eight terrace homes and four apartments, was awarded Australia’s first 6 Star Green Star Design rating for a residential project by the Green Building Council of Australia when construction commenced in 2015.
An application has also been lodged for an As Built rating, with certification expected in 2018, according to DHA senior development manager Stephen Hutchinson.
The project was a collaboration between DHA, Prince’s Trust Australia and Renewal SA, and Prince Charles himself turned the first sod at a ground breaking ceremony.
The design concept was developed by Architekton, a UK consultancy associated with the Prince’s Foundation for Building Community in London.
Hutchinson says the design was then detailed to ensure it complied with the Australian building code, while still bringing in the most up-to-date experience in low carbon building from the UK.
The homes are expected to use 50 per cent less energy and potable water than a typical townhouse. They are also expected to generate 55 per cent less greenhouse gas emissions compared to a standard home.
The average NatHERS rating of the dwellings is 7.2 stars.
Reducing supply chain carbon emissions and embodied carbon was a specific focus for the project team. As part of the strategy, local products and suppliers were prioritised to minimise transport-related emissions.
“We committed to not only sourcing sustainable products, but ensuring that the emissions hidden in the supply chain were also reduced,” Hutchinson says.
“This includes the indirect emissions produced during the manufacturing and transportation of materials.”
Local builder Palumbo was contracted to construct the project, and tasked with obtaining materials and fixtures that met Green Star requirements and preferably came from the Adelaide area.
They included 100-year old heritage bricks salvaged from heritage demolition sites for the facade of the mews.
A sustainable concrete from Port Adelaide comprising a mix of recycled rubble, slag, fly ash and reclaimed water was also used, along with SA-quarried black granite, Adelaide-manufactured pavers, Adelaide-fabricated wrought iron balustrades and certified sustainable Australian timbers.
Local company Historic Stone Restorations carved the Prince’s emblem – The Prince of Wales’s feathers – which ornament both ends of the terraces.
In addition to targeting local sourcing to reduce the project’s material carbon footprint, Hutchinson says DHA also aimed to support the local economy and encourage the development of local skills and a supply chain focused on sustainability.
Over the life of the project, about 230 local trades and suppliers supported the build.
Focusing on procuring certified materials also showcases transparency and advances the market for sustainable materials, Hutchinson says.
“Throughout the construction process Palumbo and dsquared Consulting conducted rigorous screening of all materials brought to site to ensure they met all of the Green Star criteria.”
One of the lessons of the project for the developer was that, “when sustainability principles are firmly entrenched into the project identity and are a required deliverable for the project team, positive outcomes are sure to be achieved”.
Sustainable doesn’t need to mean costly
There was also some learning gained regarding available products in the market.
Hutchinson says there are a number of certified green products such as Knauf plasterboard and Dorma hardware that do not cost extra compared to less sustainable products. These can be readily used and pushed on other development projects.
There are others, however, that are perhaps not all they claim.
He says some suppliers or contractors will push “green” products, but when they are asked to back up the claims with certification, they don’t turn out to be genuinely green.
Conversely, there are suppliers and contractors that have Green Star compliant products that they didn’t realise were, so they have now gained that knowledge and can legitimately promote the products as green in future.
The Green Star As Built requirements also guided the process of the build.
As the selections for the building fabric were finalised, modelling was also updated to ensure it was meeting energy efficiency requirements, Hutchinson says.
“The handover process included building commissioning and tuning to align with Green Star criteria and to ensure all systems performed as anticipated. Acoustic testing has also been undertaken as part of the Green Star As Built rating.”
In addition to passive solar design principles, specific energy-efficiency initiatives included double glazing across all facades; solar PV arrays for all units; zoned, high efficiency air conditioning units; LED lighting; and ceiling fans in all rooms to reduce air conditioner use.
ZEGO Insulated Concrete Form blocks were used for external walls. These have twice the thermal resistance of a standard brick wall, having an R value of 4.0-5.07.
As well as having efficient fixtures and fittings to reduce potable water consumption, the project uses recycled water from the 6 Star Green Star Communities Bowden Village precinct.
The village also has multiple reserves, community amenities and a dedicated community garden that residents can use.
Hutchinson says these features were part of the attraction of locating the development within the village.
Green Star added six per cent
The project also demonstrated that going for big green goals does not mean adding substantially to the budget.
“We found that the additional costs of applying Green Star to the project to be around six per cent,” Hutchinson says.
“While this is project-specific it provides a guide for future application.
“Sometimes innovation and learning comes at a little extra cost and DHA has been willing to make a contribution for driving change.
“We hope to share our findings with industry and help others make more sustainable choices.”
DHA chair Sandy Macdonald says all three organisations involved in the project – DHA, The Prince’s Trust Australia and Renewal SA – hope to share their findings and experience with local industry and by doing so help others to make more sustainable choices.
“We have proven it is possible for small, residential projects to make big choices when it comes to moving toward more sustainable practices and supporting local communities,” Macdonald says.
The Prince’s Trust Australia chief executive Dr Janine Kirk says the organisation is “delighted to see this project move from pen and paper to bricks and mortar, ready to welcome its first Defence families in a few weeks’ time”.
“We look forward to working with communities across Australia to pioneer similar exemplar projects.”