Couple aim for sustainability trifecta with rammed earth house
Not content with an impressive 10 Homestar Design rating for their rammed earth house, Aucklanders Rochelle and Joel Payne are going for the green home trifecta.
The Beachlands couple, who are building the house themselves, hope to add a 10 Homestar Built rating and Living Building Challenge certification to their credentials.
Not only will the house be highly insulated to passive house standards, it will also generate its own power. And what is even more remarkable, no waste water or sewerage will be exported from the site, which means it all needs to be disposed off right there, on a suburban section.
While the Paynes only recently decided on a rammed earth house, they are not new to the idea of sustainability. They have already renovated their first family home in Beachlands to a 7 Homestar rating. And Rochelle Payne is a sustainable building consultant working on a PhD in the performance of green buildings.
But if you wonder if all of this will compromise the look of the house, the answer is no.
The couple are experimenting with a range of different coloured oxides to add to the rammed earth mix, and the house design by Phil Smith of Collingridge and Smith Architects looks impressive. But just to be certain of the mix, in terms of both performance and colour, the Paynes are building a playhouse first, for children Isabella 4, and Nicholas, 3.
"Anyone can do rammed earth," Joel Payne says. "If you can bake a cake you can manufacture and make rammed earth walls. There's no rocket science to it. It's just following formulae and mixtures, experimenting and playing around."
But he says there is definitely an art to building the formwork for the ramming. The Paynes' rammed earth house will differ from others built in New Zealand because they will be using a Structural Insulated Rammed Earth (SIREWALL) system, which is essentially a structural rammed earth sandwich, with insulation through the centre. Joel Payne, a former aircraft engineer with experience in the building industry, is about to attend a course on the method in Vancouver.
But what will be so different about their house? "It will be extremely energy efficient," says Rochelle Payne.
Not only will there be extra insulation in the walls, the house will also feature triple-glazed windows with thermally broken frames, photovoltaic panels that will generate all the home's energy on site, and other special features, such as electric car charging points.
"There will be a greywater recycling system and composting toilet waste system in the basement," Payne says. "I have been told that all going well, we should only need to remove the waste once a year and it will be beautiful compost for the garden."
The grey water also goes into the garden. Already, the couple have built special evapotranspiration garden beds that will accommodate the water waste from the bathrooms and kitchen.
Payne admits the Living Building Challenge is an especially aspirational part of the build. "This is not for your average homeowner," she says. "You need to be very interested and dedicated to the challenge. The hardest part is dealing with the waste matter. But we want to show people that you can do it in a residential area."
The pair are hoping their home will be the first in New Zealand to achieve this certification, but the race is on, as they know of at least three other projects that have also been registered. A completed house must be lived in for a year before certification is granted.
The completed, 340 square-metre, two-storey house will include a one-bedroom apartment, two-car garage and a roof terrace. "We were going to have a gabled roofline, but it would have created too much water run-off," says Rochelle Payne. "So it will be a flat, green roof, with photovoltaic panels attached to the balustrading."
Living areas and an office will be on the upper level to maximise the sea views.
Their ambitious project has already caught the eye of the Grand Designs NZ programme makers, but so far it is early days in the build – the couple are hopeful the building consent for the house will be through by the end of June.
The couple's green ambitions have also captured the interest of political leaders, with Labour spokesperson on housing, Phil Twyford scheduled to help celebrate the groundbreaking at a special event organised for June 30.
And in the future, the Paynes hope to share their knowledge and expertise on building with rammed earth houses, as they see possibilities in shared building projects with local iwi. In the meantime, they are posting a chronicle of their venture on livinghouse.org and Facebook.