SUSTAINABILITY | KEY AREAS
The Challenges:
New Zealanders are increasingly conscious of the importance of sustainability on multiple interconnecting levels – environmental, health, housing, economic, community and personal, with the needs of each family and household shaping priorities and decision-making.
Awareness of some of the problems impacting the quality of our housing – including climate variability, increased summer warming and extreme weather events, and the effects of some of the products used in housing on the health and wellbeing of families – is leading to a stronger emphasis on sustainability in the home building sector. This includes better understanding of:
Efficiency in the design, construction and thermal performance of our homes
The resulting reductions in ongoing operational costs
Reduced carbon footprint
Significant improvements in health, comfort and quality of life.
Better Options:
This Superhome Design Guide and the Reno Design Guide bring together a wide range of information about ways to improve the sustainability of NZ homes. There are many sources of useful information, including:
Some studies look specifically at the costs and affordability of improving the sustainability of NZ homes.
A report for the Ministry for the Environment explored the value case for sustainable building, finding that:
“Sustainable buildings are intrinsically more economic to run over their whole lifetime… Significant rises in energy costs and, to a lesser extent, water costs continue to make sustainable buildings increasingly attractive… For owner occupiers, a 20-year whole-of-life cost view indicates the marginal cost increase of sustainable building is likely to be repaid between five or six times by operating cost savings alone…
“The difference in the initial capital cost of sustainable buildings compared to conventional good quality buildings varies from 15% less to 11.5% more, with sustainable features initially costing an average of 2-6% more.”
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The NZ Green Building Council commissioned a report (2025) analysing the financial benefits which found that building for sustainability, with an upfront increase of between 0.5% to 1.5% of average conventional building costs, compared to Building Code minimum, would save homeowners significant sums:
“Electricity and [mortgage] interest savings combined range from almost $62, 800 for a terraced house in Auckland up to $98,800 for a standalone house in Wellington over the [typical 30-year] life of the loan.”
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A BRANZ report exploring costs and expectations within the NZ home building sector found that although there are perceptions that building sustainably is inherently more expensive, the actual cost premium for the majority of green certified buildings is less than 4% more than for a standard construction. A significant proportion of the green buildings analysed for the study had lower costs than conventional construction methods:
“On the whole, green buildings are not inherently more expensive due to their provision of sustainable materials and systems… They can in fact be considerably less expensive…
“Importantly, the research also shows that decreased energy and operational costs mean that, even when there’s a cost premium, this is offset by lower energy and operational costs.”
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Energy efficiency:
A key factor in sustainability is energy efficiency, improving the operation of the home with insulation, airtightness, ventilation, recessed windows, thermally broken window frames, and effective heating systems as outlined in this Design Guide. Intelligent design is crucial to integrate the various systems in the home to work together for the best results:
“Heating is just one element of your whole home. A house acts as a full package, so if you have a cost effective heating solution but you don’t have a very well insulated home, it’s going to cost alot to run. If you have a very well insulated house but you don’t have a very good heating solution you’re still going to suffer from the cold. The design becomes the fundamental part of the build.”
Hanshu Li, Warmth NZ
“Clever design, smart thinking, and flexibility can help more people access healthy, energy-efficient homes.”
Brent and Claire Chatterton, Chatterton Homes
“That’s a high performance home, that’s why you have a Superhome, because we’re not losing the energy that we’re creating in the home, we’re not having the intrusion of cold into the home – your net cost is lower. It might have cost a little bit more to build, but at the end of the day it costs less to run, and is more comfortable and more healthy, it makes sense”
Guy Gillespie: Character Builders
“When people come into a house and they’ve got SIPS panels and PVC windows, they’ve got a ventilation system, just what the environment’s like – people go ‘WOW, this feels so comfortable.’Then I tell them that for 9 months of the year I don’t pay a power bill either, then they go right, OK”
Peter Davis: AD Architecture
“65% of our operating power bill goes into your hot water heating, your space heating – so if you can take care of these, you massively reduce the running costs of your property. Those are the things that we can be smarter when we design.”
Hanshu Li: Warmth.nz
“Power savings – particularly Superhomes, because consumption is alot lower, we can design a smaller system than if your home isn’t as energy efficient.”
Chris Dearsley: Harrisons Solar
“Environmental tools, environmental analysis, energy efficient modelling, incorporating those into the design... our job is to take that information and adapt that to design – you’re not letting technical data drive the design, you’re letting it inform the design.”
Duncan Firth: Solarei Architecture
“Think broadly of all the costs in building a home, and the savings, SIPs become alot cheaper – costs of day to day running comes down. When people talk costs, a square metre cost, you need to add the cost of life, of ownership”
Gary Peters: SelectSIP
“If you’re building a Superhome or a high performance home, yes, it costs a little bit more up front, but it’s an investment for the next 15, 20, 25 years. That investment pays itself back, not only in things like heat recovery but in your health, and less energy use – there’s lots of benefits in building those homes that you’re going to be in for a long period of time, as Superhomes”
Marcus South: Warmth.nz
