​Maximise the potential of your build site

05 March 2019

Guest contribution by Toby Tilsley, Homestar Assessor of NZGBC member, Craft Homes

We are excited to be nearing completion of a 7-month sustainable build project in a little place called Huia on the Manukau Harbour, Auckland. The home is an environmental, passive solar design by Duncan Firth from Solarei, with the Craft Homes team as principle contractor. We aim to have this house certified as a 7 Homestar.

Like with all good design orientation plays a big part, with the home positioned to capture the most sunlight, warmth and air flow throughout the day, as well as the amazing view! Another important design feature are the solid block walls that have been strategically placed within the house to provide thermal mass to capture the natural radiant energy from the sun during the day and release it slowly at night, therefore providing a heat source for the property.

In terms of innovation, this home has packed a lot in. The external cladding is Innowood, which is a sustainable timber alternative. This product is a composite of wood waste and resin, which is low VOC, 100% recyclable, durable and lightweight and has an unrivaled fire rating, a must for the owners who come from California.

The insulation has been supplied and installed by the team from Enveloped, who have used Earthwool Glasswool, which is a product made using recycled glass and sand that is also low VOC. In terms of insulation ratings R5.2 was used in the ceilings, R3.2 in the walls and a R3.2 blanket under the floor is protected from external moisture by Pro Clima Solitex Extasana building wrap. Pro Clima membranes have also been used for the exterior walls and flexible membrane flashings. The connecting foundation was thermally broken using Climafoam XPS. All of this should make for a very cosy winter ahead!

The property will also have grid tied solar panels from Ecosmart with a ground array of 21 panels producing 5.7 kilowatts of power. To make the most of the high rainfall in the Waitakere ranges we are currently installing a rain water harvesting system with in-ground water tank that captures water and pumps it back to the house. A passive septic system from Naturalflow will also be installed, which separates black and grey water at source, with black water passing through a Wormorator and grey water being filtered before being released for irrigation.

As this project has shown, 2019 is looking bright for the availability of innovative products and materials within NZ. These innovations can take the comfort and health of a home to the next level, as well as working to reduce running costs and the overall environmental footprint for many years to come.

Craft Homes

www.nzgbc.org.nz/homestar