When does a new home need a BASIX certificate?
Every new home in NSW needs a BASIX certificate. BASIX (the Building Sustainability Index) sets minimum standards for water use, energy use and thermal performance. The certificate must be lodged with your development application or complying development certificate. Renovations costing $50,000 or more and pools of 40,000 litres or more need one too.
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What BASIX measures
The NSW Planning Portal describes BASIX as a set of standards for water, energy use and thermal performance that applies to all new residential dwellings. Your council or certifier cannot approve a new home without evidence that its design meets them. The assessment also reports the embodied emissions of the main building materials through a materials index.
The standards rose on 1 October 2023, when the Department of Planning aligned BASIX with the National Construction Code 2022. The thermal target for a new house moved from an average of 5.5 to 6 stars to 7 stars on the Nationwide House Energy Rating Scheme (NatHERS). Only homes in climate zones 9, 10 and 11 in north-eastern NSW were left out of that increase. Greenhouse gas emissions also had to fall by 7 to 11 per cent depending on location and building type.
When the BASIX certificate is needed
The certificate is needed before your home can be approved. The Planning Portal explains that you assess the design in the online BASIX tool and then lodge the certificate with your DA or CDC. The tool works from details such as the floor area, the size, position and type of each window, the insulation and the hot water system.
The finished certificate lists the key elements of the design as sustainability commitments. Those commitments become part of what the house must deliver, so they need to carry through to the construction drawings and specification. A BASIX certificate is therefore a design document as much as an approval form. It is easier to meet well when the designer works with it from the concept stage.
Does BASIX change during construction?
It can. If a commitment such as the glazing system or hot water unit changes during the build, the certificate has to be revised, which creates a new reference number. Some changes may also need the approval to be updated, so raise any swap with your designer and certifier before the product is ordered.
BASIX is signed off at the end of the build. After the final inspection and before the final occupation certificate is issued, your certifier must issue a BASIX completion receipt for each certificate. A commitment that was not delivered can hold up the certificate you need to move in.
How BASIX shapes the design of a custom home
For a custom home, the thermal standard is usually the part of BASIX that asks the most of the design. Orientation, glazing, shading, insulation and the way rooms open to the sun all feed into the rating. Much of the result is settled on the drawings long before the trades arrive. Large areas of glass facing a harbour or ocean view need careful attention to glass type, frames and shading.
The higher standard does carry a cost. When it introduced the 2023 increase, the Department estimated that an average house in Blacktown would cost $7,152 more to build. It also estimated that the average home meeting the new standard would save $1,070 a year on energy bills. Those were the Department's estimates for average homes at the time, so a custom home's result depends on its own design.
How we work with BASIX at SHORE
As our design and build process shows, we begin with the brief and the block. Orientation, fall and outlook shape how a house performs as well as how it looks. Our builders sit in the same studio and price the concept as it takes shape, so the design never drifts ahead of what the budget can hold.
In design development we settle materials, openings and ceiling heights inside the budget. Our construction documentation is then prepared by the people who build from it. That keeps the commitments on the certificate and the house on site aligned through to handover. To see how this fits into a new home from first visit to handover, explore our custom homes in Sydney.
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