Stockland’s new Zero Net Carbon home

Published: 2 November 2020

Objective

In 2019, Stockland joined Sustainability Victoria’s Zero Net Carbon Homes (ZNC) program to get support for the design, construction and marketing of high-efficiency, low-emission homes. By 2020, the company finished its first ZNC home, Apollo, a three-bedroom town home that is part of Stockland’s Orion development in Braybrook.

Outcomes

  • The project showed that medium-density housing can achieve ZNC status, even if it’s one home and not an entire development stage.
  • Further, that improved energy efficiency leading to homeowners’ savings makes a strong value proposition. The National Construction Code requires a 6-star NatHERs rating and the ZNC program requires 6.5 stars.

Home snapshot

Name of the home: Apollo

Estate: Orion

Address: Braybrook VIC

Home Builder: Creation Homes

Land Developer: Stockland

Size: 126.2 m2

NatHERS energy rating: 7 stars

Carbon status: Net Zero Carbon

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Introduction

Australian property group Stockland is creating thriving communities that reduce waste, encourage healthy living and contribute to a sustainable future.

General manager of Built Form Communities Ben Cantwell said, “There are some people who want to do the right thing for the environment by going for sustainable homes. But there are also many people who will take up these options to help them reduce their cost of living.”

CEO of Sustainability Victoria, Claire Ferres Miles said: “The ZNC Homes program has provided technical and marketing expertise to Australia’s leading residential builders to facilitate the development, marketing and sales of higher quality more comfortable homes that contribute to Victoria’s goal to achieve zero net emissions by 2050.

“We look forward to continuing working with Stockland to accelerate the construction of more ZNC homes,” she added.

Home design and build

Stockland decided to aim for 7 stars, which reduces the heating and cooling loads by 30% compared to a standard home.

Sustainability Victoria worked with Stockland to find ways to increase the energy efficiency rating of the original home design through different measures.

Modelling data shows that four people living in the home rather than a standard home can:

  • enjoy lower heating and cooling loads
  • enjoy 50% lower energy bills (about $1000 per year)
  • produce no net emissions from the energy use in the home
  • reduce gas emissions by about 4.7 tonnes per year.

Orientation analysis

This table shows the difference orientation makes to the efficiency of the home, with North as the most favourable orientation and West the least favourable, for this property.

Living area orientation Azimuth (°) Heating load (MJ/m2) Cooling load (MJ/m2) Total energy loads (MJ/m2) NatHERS rating (stars)
North 0 81.9 13.7 95.6 7.1
Northwest 45 83.6 23.5 107.1 6.7
West 90 84.8 32.6 117.4 6.4
Southwest 135 86.9 15.7 102.6 6.9
South 180 87.9 10.1 98 7
Southeast 225 88.2 13.8 102 6.9
East 270 80.3 21.6 102 6.9
Northeast 315 77.7 15.9 93.6 7.2

As-built verification

A blower door test and a thermal camera were used to check if the insulation was installed properly. Results showed that the home was draught-proof with only 4.3 air-changes per hour.

Air-tightness and insulation integrity results

The townhouse exceeded the requirements for air-tightness and insultation testing.

Requirement Target Achieved Value result
Air-permeability in m3/m2.hr @50 Pa max 6.00 4.36 Passed
Insulation non-coverage walls max 5% 0% Passed
Insulation non-coverage ceiling max 5% 0.25% Passed
Insulation non-coverage floors max 5% 0% Passed

Conclusion

  • It’s important to consider energy efficiency in the design phase before the project starts. Retrofitting energy efficiency into the design during construction phase can increase costs by 100%.
  • When planning a sustainable development on a large scale, orientation is a relatively low-cost way to increase the NatHERS rating. The right orientation can add 0.8 NatHERS rating without costing anything extra .
  • Sustainable design is more about good building practices than innovative technologies.
"We see energy-efficient homes as the future of residential building. Thanks to the ZNC program, we are upskilling our sales teams to demystify the complexities and sell the benefits of sustainable home design."
Ben Cantwell, General manager of development, Stockland