In 2003, the Building Code of Australia (BCA) introduced thermal performance requirements for residential buildings. It mandated a minimum performance rating of 4 Stars when assessed by approved rating methods. In 2006, this requirement was increased to 5 Stars. The 4 Star requirements were a major initiative, as they introduced insulation and glazing requirements for the first time. The move to 5 Stars tightened insulation and glazing requirements and affected houses with a platform floor in cooler climates as it required the use of subfloor insulation, a previously uncommon practice in Australia.
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