Certified green buildings in New Zealand are jumping with exponential growth, especially in the residential sector, as the industry takes up where the government left off in mandating higher quality housing.
According to NZ Green Building Council’s director of market transformation Sam Archer there has been a 10-fold increase in Homestar ratings, from around 650 to over 6500 in the past two years.
The NZGBC is in growth mode with staff now at 17, and moves to bring more tools onto the market.
A version of the Green Building Council of Australia’s Green Star Performance tool will be introduced soon, and there is already considerable interest from property owners, Mr Archer said.
Green Star Design and As Built tools have also become “standard” for new office developments in NZ.
This is a small and dispersed market comprising around two per cent of commercial space, however, so the NZGBC aims to target the 98 per cent of existing buildings.
The residential though is streaking ahead. Mr Archer said part of the reason was that ratings had been mandated by authorities for developments in parts of Auckland – a policy that has since been rescinded.
The end of the policy, however, has not slowed uptake, in fact more of NZ’s residential construction industry is engaging with the tool.
Some of the move is also driven by quasi-government agencies delivering a mix of social and private housing.
Health a major driver of green buildings
A major incentive in the movement for Homestar ratings is concern for occupant health, with New Zealand having some of the poorest quality housing in the developed world..
The nation has the second highest asthma rate of any developed nation, and the very wet, cold maritime climate means homes have issues with damp and mould.
“Housing is a huge health problem,” Mr Archer said.
NZ also has some of the lowest standards in terms of its construction code and insulation requirements.
There are no requirements for thermal comfort or energy modelling, unlike the Australian National Construction Code, and single glazing is allowed.
Councils moving to tackle climate change
Many councils also want more sustainable housing because of concerns around climate change, Mr Archer said.
Those who have used the tool and obtained a rating have been happy with the process, he said. A new version of Homestar – Homestar V4 – is in the works, which will be quicker and cheaper. It is due to be launched in the final quarter of this year.
Volume builders and major developers have indicated a willingness to use the tool if it is “not too complex and expensive”.
And the timing is good. Because housing supply and affordability are critical policy issues, there are a substantial number of homes currently being built or planned. The NZGBC wanted to ensure they were high quality, Mr Archer said.
10 star homes
The Homestar tool gives ratings of between one and 10 stars.
There are currently five houses that have achieved 10 Star ratings – in Christchurch, Wellington, Tauranga and Auckland.
A Wellington house by Eco Green Homes was the first to receive a 10 Star rating under Homestar V3 Design.
Sustainability elements include enhanced daylight from solar powered skylights, low VOC paints, high levels of insulation from structural insulated panel walls, triple-glazed windows, slab-edge insulation, ceiling insulation and an electric car charge point.
“Our mission is to make green homes affordable to the New Zealand market,” Eco Green Homes’ Kush Bhargava said.
“In this day and age, there is no excuse not to build green. The benefits far outweigh the costs with no compromises on quality or comfort. Ultimately these homes save significant costs in the long run.”
Mr Archer said the home’s design was international best practice.
“It just goes to show that Homestar designed and built homes can maximise the living quality of occupants, while minimising costs. It’s a no-brainer.”
The sustainability trifecta
Another recent 10 Star V3 Design rating in Auckland is targeting the “trifecta” of sustainability – Homestar, Living Building Challenge and Passive House certification.
The four-bedroom, two-storey with attached one bedroom apartment “Living House” is being developed by a husband and wife team – Joel Payne, a building materials business owner, and Rochelle Payne, a sustainable building consultant.
It will be constructed from rammed earth with a low pitch green roof complete with solar panels. It will also have rainwater tanks to provide potable water, composting toilets and a greywater filtration system with subsequent dispersal into evapotranspiration beds.
Mr Archer said the NZGBC’s aim was to see all new homes built to a 6 Star Homestar standard as a minimum – a level of quality that is better than code minimum.
“10 Star aspirational homes are great, but we are interested in bringing the masses up to 6 Star.”
To achieve 6 Star, a home needs to have insulation better than code minimum, water efficient fixtures, FSC-certified timber and low-VOC paints and finishes. Building waste also needs to be managed well, and where possible diverted from landfill.
The cost premium for a home of this quality is about a 2.2 per cent increase in build cost. The cost of certification is $900, and where multiple homes are being constructed, that cost is applied per home typology as a bulk certification arrangement.
Mr Archer said most developers aspire to that standard anyway.
One of the elements being added for Homestar V4 is blower door testing to test for leaky construction.
“It is about finding a balance, and considering if the industry is ready.”
Mr Archer said that in Australia GRESB has driven a lot of uptake in performance tools.
“A lot of FM teams are also liking Performance [ratings] because it is a lever to look at their building stock and see which buildings are performing least well, and then go to management and get more money to improve them.”