Architectural designer Bob Burnett is on a mission to transform how the people of Aotearoa think about residential property with his zero carbon Superhomes. His latest foray into ultra energy efficient homes includes dramatically reduced concrete, timber piles instead of concrete slab and the use of laminated glulam structural beams instead of structural steel.
In 2016, Bob Burnett tackled the woeful performance of much of the housing in Aotearoa (New Zealand) with the country’s first 10 Star Home Star Superhomes. The dwellings were the vanguard of a movement, which saw roadshows, demonstration projects and the free sharing of design and delivery information for ultra-energy efficient, comfortable homes that also mitigated the common local risk of unhealthy “leaky homes”.
- Read the story here
He says that thousands of people have accessed Superhome information.
“We did the (first) development to create awareness of where the building code in New Zealand sits,” he says.
Show before you sell
Giving people the opportunity to walk around the 10 Star homes and experience the difference is crucial to gaining market traction.
“Before that, people only had the opportunity to visit show homes built to building code [minimum] standard,” he says. “Over 80 per cent of people decide what they will buy based on a display home.”
So, showing the market what better looks like and dispelling myths about high performance homes helped dissolve perceptions and gain acceptance. The initial momentum has evolved into the Superhome Movement Charitable Trust, sharing information, educating the value chain, and advocating for improved residential design and delivery.
“A lot of it is about better design,” Burnett says. “The common perception is it will be more expensive, but a lot of good design ideas don’t cost more.”
Nga Whare Parara – the next big leap
Now he’s bringing zero carbon Superhomes to market, with a development of four dwellings on a standard large residential block in Somerfield in the southern part of Christchurch.
The Nga Whare Parara (to warm oneself, or bask in the sun) development comprises two detached two-storey dwellings and two two-storey semi-detached homes. All have four bedrooms, three bathrooms and open plan living, with solar PV and rainwater capture and use.
The homes are using relatively simple technologies including heat pump hot water systems, heat recovery ventilation systems, automated shades for overheating protection on the most sun-exposed home; and electrical schematics that are EV-ready.
The passive design moves around orientation, cross ventilation and appropriate solar shading such as wide eaves are a key part of achieving high performance. The materiality is also crucial and includes: EcoPanel prefabricated insulated wall panels; European triple-glazed windows with thermally-broken frames; and insulation to floors in addition to ceilings and walls.
Pressure testing will be carried out at completion to verify an air tightness aligned to Passive House standards.
The homes are using relatively simple technologies including heat pump hot water systems, heat recovery ventilation systems, automated shades for overheating protection on the most sun-exposed home; and electrical schematics that are EV-ready.
Benchmarking and verification
Burnett says that zero carbon means both the upfront carbon of materials and construction, and the carbon emissions of the operational phase must be balanced out to net zero. The modelling and analysis he and the team have undertaken for the development, using New Zealand software V-Quest, shows the homes will be net zero from day one of occupancy.
Environmental product declarations were necessary for every product and material in the project. This was “quite a learning curve” for the practice
The software uses local data for the carbon of materials and can be coupled with the architect’s CAD design software to help optimise structural design and materials specifications for reducing carbon. It also provides the design team with data on the final carbon figures for every item in the homes.
Burnett says environmental product declarations were necessary for every product and material in the project. This was “quite a learning curve” for the practice.
Procuring for zero carbon
Decisions were made to reduce the amount of concrete dramatically by designing for the homes to sit on timber piles rather than a concrete slab. Structural steel was avoided, instead, NZ-produced ProLam laminated glulam structural beams were procured. These are low carbon and are also good for earthquake resilience, Burnett says.
Specifications prioritised recycled, local and low carbon materials to the greatest extent possible.
Another element of the embodied carbon equation is the demolition phase. The block was formerly home to a villa constructed in 1906. This was not demolished, instead it was removed intact and relocated for another life in a community of similar relocated heritage villas.
The glazing, however, was procured from Poland, a choice Burnett says was made because there is not a local product with the same quality in terms of performance. Ocean shipping is the lowest carbon freight, he notes, and the product came with high environmental credentials.
Cost-wise, the windows from Poland landed in NZ came in at an equivalent cost to a local product, while delivering better for performance.
Procurement and specification made his team “rethink the whole supply chain, and all the materials we use.”
Another element of the embodied carbon equation is the demolition phase. The block was formerly home to a villa constructed in 1906. This was not demolished, instead it was removed intact and relocated for another life in a community of similar relocated heritage villas.
Uplift for biodiversity
around the homes was also a priority for the development planning. Burnett explains they could have fit seven homes under the local planning scheme; however, he says the development is about “people before profit”.
“Our focus was on designing the best possible living environment for people,” he says.
A landscaping plan has been created that incorporates fruit trees, native trees and shrubs, flowers, herbs, and vegetables.
“We were thinking about an uplift in biodiversity,” Burnett says.
It’s another of those things – like carbon – that are not top of mind for many home buyers. Increasingly though, he says they are thinking about energy efficiency and comfort.
Leaning into principles, not ratings
While the designs included some passive design principles, Burnett is not seeking formal ratings. The carbon outcome is being verified by the VQuest software and post-occupancy energy monitoring.
“It is about how do we promote better design, not just a one-dimensional thing around building performance. It is about being spatially aware, having the openings in the right place, having high ceilings. We do more with less.”
Heads up on heat
Burnett says one of the difficulties when designing to avoid overheating can be perverse outcomes, such as smaller windows. His goal was to have the home interiors bathed in light, while still avoiding overheating in summer, something that is increasingly an issue in NZ.
“There has been a lot of noise recently in the media about apartments and homes overheating,” he says. “And (the proportion of dwellings) overheating will potentially double by 2040.”
He looks forward to bringing the public along on the journey, and letting people see the homes while they are under construction, before everything gets covered up.
“We can’t design and build all the homes that are needed ourselves, so we give the knowledge away.”
One of the homes has sold for $NZ1.2 million ($1.08 million), three are for sale at between $NZ1.2 million and $1.5 million ($1.08 million to $1.35 million).