6 The construction of buildings in Victoria is governed by the Building Act 1993 and the Building (Interim) Regulations 2005 ("the building regulations"). The principal objective of the building regulations is to prescribe standards for the construction of buildings. The regulations adopt the Building Code of Australia ("the BCA").[3] Under the building regulations buildings are classified as set out in the BCA.[4] It is common ground that the proposed dwellings would be Class 1 buildings pursuant to the building regulations and the BCA.
7 The regulations and the BCA contain detailed provisions in relation to energy efficiency in new dwellings. Under the "deemed to satisfy" provisions of the BCA, all new Class 1 buildings are required to achieve a 5-star house energy rating. (There are certain exceptions in relation to Class 1 buildings of timber floor construction or earth wall construction.) New Class 1 buildings also require either a rainwater tank, connected to all sanitary flushing systems, or a solar water heating system. All new Class 2 buildings are required to achieve an average 5-star rating for dwellings in a building, but each sole occupancy unit need only achieve a rating of three stars. Further, there is no requirement to install a rainwater tank or solar water heating system in a Class 2 building. A support system of energy raters, rating software and technical guidelines has been created to assist applicants meet these standards through the building approval process.
8 The building regulations also provide transitional arrangements to allow the industry to cope with change. Section 10(2) of the Building Act provides that if a building surveyor is satisfied and certifies in writing that substantial progress was made on the design of a building prior to a building regulation commencing, then the building regulation does not apply to the carrying out of the relevant work. In the case of individual "one off" designs, the date of the relevant plans is normally taken to be evidence of substantial progress in relation to the design.[5] In the present context this is relevant. The plans are dated 31 December 2004, at which time there were various options for Class 1 dwellings, one of which was to achieve a 5-star house energy rating, without providing either a rainwater tank or a solar water heating system.
9 It is also important to note that the required house energy rating is implemented using the BCA, which is a performance based building code. Compliance with the BCA can be achieved by complying with the prescriptive requirements, such as the 5-star standard, or by developing another solution which demonstrates that the proposal meets the relevant performance requirements. Further the requirements of the BCA can be waived, modified or varied by the Building Appeals Board.[6]
10 The 5-star standard was introduced following a Regulatory Information Bulletin. The requirement that new Class 1 buildings have a rainwater tank or a solar water heating system was introduced on 29 June 2004 by the Plumbing (Water and Energy Savings) Regulations 2004.