The first development to be rated under the NZ Green Building Council’s Homestar v3 tool has achieved a minimum of 7 Homestar Design for 113 dwellings in Auckland’s Wynyard Central, including apartments, pavilions and townhouses.
The rating is three stars above the average performance of a new business-as-usual dwelling, the NZ Green Building Council said, and the largest project to date to achieve any Homestar credentials.
Making the homes greener and more energy efficient only means about a 3.5 per cent increase in the build cost compared to code minimum, according to David Fullbrook, director of the project’s sustainability consultants, eCubed Building Works.
The new Homestar tool was piloted and sponsored by the Wynyard Central project’s developers, Willis Bond &Co, to enable them to meet the benchmark set by the land owner, Panuku Developments.
Panuku is a wholly owned entity of Auckland Council that is undertaking the wider urban renewal project across Wynyard Quarter, which includes Wynyard Central and North Wharf. The parcel of land, which is owned by the council, is situated on the Auckland waterfront and was formerly used for industrial purposes and the fishing industry.
The land is being leased to both residential and commercial developers on a 125-year term, with the lease fee paid upfront before development commences.
It is a requirement under Panuku’s sustainability and planning frameworks that all residential developments in the Quarter must achieve 7 HomeStar or better. The problem was, the existing Homestar required updating to suit high-density developments.
Some of the new credits in the updated Homestar include rewarding shared areas that promote community activities, such as gardens and playgrounds; levels of natural light within apartments; efficient heating and airconditioning; and development on brownfield sites like Wynyard as it minimises urban sprawl.
NZGBC chief executive Alex Cutler said the updates make Homestar more flexible.
“The growing pressure on housing supply is a major issue for New Zealand, and increasing the density of our cities is the most sustainable way to meet that growing demand,” Ms Cutler said.
She said the new tool would ensure that multi-residential projects provide dwellings that are energy efficient, healthy and liveable, with good community facilities and green space.
“By updating Homestar for higher-density projects, we’re keeping pace with industry needs.”
Another Auckland developer, Ockham Residential, was an associate sponsor of the tool. Its Daisy project at Mt Eden is on track to achieve a 9 Homestar Design rating, Ms Cutler said.
There are currently more than 2500 dwellings, including low-, medium- and high-density homes, registered for Homestar, an enormous increase in uptake compared to the 550 registered at the same last year.
Ms Cutler said typical existing homes in NZ rate around 2 to 3 Homestar, and a new home built only to minimum Building Code standards would achieve around 4 Homestar.
Mr Fullbrook said that the Wynyard Central project overall cost around seven per cent more, with the added cost split 50-50 between the requirements for the apartments and the requirements for common area and precinct-wide sustainability initiatives laid down by Panuku.
He said most Auckland apartments, particularly at the lower end of the market, had “no sustainability features at all”.
There were a number of things that contributed to the 7 Homestar and 8 Homestar ratings the Wynyard Central dwellings have achieved that were easy wins, he said. These include about 90 per cent of the apartments having a double aspect that gives good natural ventilation and natural light.
The building envelope is being well-insulated, and all glazing will be low-e or double glazing.
“That all means that around 80 per cent of the time there will be no heating or cooling needed,” Mr Fullbrook said.
The rest of the sustainability initiatives for the dwellings that achieved credits involved “a really careful selection of materials and appliances”, he said.
These include WELS rated tap-ware and fixtures; Energy Star-rated appliances; 95 per cent LED lighting; energy-efficient heat-recovery ventilation systems and heat pump heating; double-insulated hot water cylinders; smart metering for individual apartment energy and water use; and low-VOC materials that carry certification either by ECNZ or another NZGBC-approved eco-label.
“The apartment side was easy; the common areas and precinct wide areas are more difficult to achieve.”
Common area initiatives include providing share car space, EV charging points, cycle storage and also a stipulation by Panuku that no apartment can be sold with a car park – the car parks must be sold separately.
They are being priced at $100,000 each, and Panuku’s senior sustainability advisor Dr Viv Heslop told The Fifth Estate that putting a separate price on car parks was part of a strategy to help residents understands that the land used just for cars “has value”.
It is also part of a broader aim to encourage 70 per cent of people to use active travel at peak travel times including walking or cycling or public transport instead of private cars.
The project has also planned for green roof areas, rain gardens, recycling and composting facilities, and will include low speed shared streets and laneways.
One of the initiatives that Willis Bond does not have to budget for is solar power generation for common areas, as this will be provided by a third party under a power purchase agreement, Mr Fullbrook said.
The use of rainwater harvesting, he said, was “not cost-attractive”, even though it has been included. Due to the small ration of roof catchment relative to the number of dwellings, there is insufficient capacity to harvest sufficient water for all the dwellings to use it for toilet flushing. So the rainwater will be reticulated for common area use and a small number of apartments instead.
More broadly, he said, in NZ there has not been the same drivers around rainwater uptake as there has been in Australia, where water supplies are often more limited. This impacts the price of rainwater harvesting and storage items in NZ, making them relatively more expensive.
All developments under Panuku’s planning must include climate change resilience features. Mr Fullbrook said the initiatives at Wynyard Central include the threshold of all ground floors set to accommodate a 1m sea level rise.
The heat pumps for the HVAC systems have been oversized to accommodate a one-degree average temperature rise, and as they only last 25 years, he said the next ones installed as part of replacement upgrades will be even more oversized.
The stormwater system has also been oversized to allow for a 16 per cent increase in the frequency of one in 100 year storm events. All the building designs have also been tested in wind tunnels to check resilience in the event of extreme cyclonic wind events.
“Up until one or two years ago, most developers wouldn’t have considered [climate change],” Mr Fullbrook said.
He said 80 per cent of developers in the country were “still take the minimum standards approach”.
Willis Bond managing director Mark McGuinness said the company aimed to create some of NZ’s greenest urban precincts, and that using the rating tool was a way of verifying for buyers that the dwelling has been designed for genuine sustainability.
“The Homestar system is a simple and effective way to inform customers about the quality and benefits of sustainable and energy efficient homes,” Mr McGuinness said.
The developer this week reported that 60 per cent of the dwellings have already sold, many at prices upwards of $1 million.