Christchurch will soon boast one of New Zealand’s most sustainable homes, with a house under construction in Addington achieving 9 out of 10 under the Homestar rating system — the highest Homestar rating awarded to date.
Homestar is the independent system that rates the health, comfort and efficiency of New Zealand homes, on a scale of 1 to 10. It takes into account energy, water, waste, ventilation, health and comfort, and other environmental factors, at the design and built stages.
The 140sq m, two-storey home in Church Square, Addington, is under construction and due for completion in late June 2015. An adjacent single-storey house in the development is also targeting a 9 Homestar Design rating.
Developer and architect Bob Burnett is a long-standing advocate for sustainable design. He’s also part of an industry group aiming to encourage 1000 new houses in Christchurch that rate 7 Homestar or more, in a bid to create a more sustainable rebuild.
“The rebuild is an unprecedented opportunity to make the city’s housing stock warmer, healthier and more energy efficient. A little extra thought and good design at the outset will lead to a lifetime of savings and good health,” Mr Burnett says.
New Zealand Green Building Council chief executive Alex Cutler says it’s particularly pleasing to see an inspirational example of sustainable architecture in Christchurch.
“As the city rebuilds, a project like Church Square shows that embracing sustainability is not only smart but desirable. This home is stylish, energy efficient and built to high standards of earthquake resistance — it’s a fantastic milestone for sustainable home building in New Zealand,” Ms Cutler says.
“Congratulations to Bob and the team for getting the first 9 Homestar Design rating and showing real leadership in the sector.”
The home features rain water harvesting and grey water, water-efficient fittings, photovoltaic solar power and energy-efficient lighting and electrics.
All paints and sealants are low VOC, and other materials are certified by Environmental Choice NZ or the Forest Stewardship Council.
A solar wall ventilation system uses the sun’s energy to pre-heat ventilation air, substantially reducing heating expenses. Slab-edge insulation (to stop heat loss from concrete floor slabs) and innovative hydronic underfloor heating also keep the home snug.
The strict waste management plan meant there was no skip bin on the building site, forcing workers to think about how to reuse and recycle as much as possible.
A high-performance thermal envelope has been achieved thanks in part to an innovative framing system called “Frame Saver”, which significantly reduces the amount of timber used and allows room for more insulation.
Additionally, external wall frames are at least 140mm thick and have a chemical-free Rigid Air Barrier (RAB). These innovations also provide superior resistance to wind and earthquake loads that far exceed Building Code requirements.