As part of the National House Energy Rating Scheme (NatHERS), the Victorian Building Regulations require that all new homes and renovations must comply with the “6-star energy rating” standard. This energy rating is a measure of the thermal performance of the overall building. It is an energy efficiency rating that applies to the building envelope (i.e. the external structure of the home) including its walls, roof, floor and windows. The main objective of the Energy Rating Scheme is to help make Australian homes more comfortable to live in and to help save on energy bills through smarter design choices.
All new homes and renovations must also include the installation of either a solar hot water system or a rainwater storage tank for flushing the toilets. The six-star requirements also include mandatory energy efficiency standards for the lighting in the home but does not include plug in appliances.
For renovations of existing homes, if the alterations represent more than 50% of the original volume of the building, the existing building must be brought up to the same six-star energy rating standard as the new construction. However, your building surveyor does have discretion to allow partial compliance where these energy rating requirements are overly onerous, technically impractical or do not provide a level of benefit commensurate with cost.
To determine the compliance with the energy efficiency requirements of the home, a thermal performance assessment or “energy rating” must be done by an accredited energy rating assessor. They will do a comprehensive evaluation of the construction materials, window frames and glazing, insulation details and the orientation of the building. They will also evaluate the heating and cooling loads and the type of proposed heating and cooling systems (see FAQ No. 17 & 18).
The Victorian Building Regulations require that the energy assessors use an accredited “House Energy Rating Software” program such as “Accurate, BERS Professional or First Rate” and they must issue an energy rating report and a “six-star energy efficiency certificate” prior to the issuing of a Building Permit.
Meeting a 6-star energy compliance should not be difficult but must be considered in the early stages of design. The biggest effect of the 6-star requirement on the architectural homes that DDB designs and builds has been on the windows and glazing. All our new homes and renovations now have fully double-glazed windows and doors and some of the homes also need high performance “Low E” glass and or “thermally broken” window frames to achieve the 6-star rating. These design requirements have added to the building costs but help to significantly reduce the running costs of the house and result in long term benefits to the environment. To maximize these benefits, several of our clients elect to design and build a home that goes well beyond the minimum energy rating requirement by investing in 7 or 8-star energy rated homes.