Energy rating star indicates the heating and cooling energy demand per unit area of a house. For instance, a 6 Star house in Melbourne is designed to have a maximum of 32 kWh per m2 of indoor areas.
A 0-star house means the building fabric does nothing to maintain comfort levels inside the house
A 5-star house is the thermal comfort level you feel in houses built from 2005 to 2011 in Victoria.
A 6-star house is the minimum level of energy compliance for houses designed before October 2023.
According to VBA, 6-star houses are projected to use 24% less energy for heating & cooling compared to 5-star houses.
A 7 Star house is a new level of energy compliance for houses designed and built for NCC 2022 compliance.
A 10-star house is a 100% passive house with almost no artificial heating and cooling demand to keep the house temperature and humidity at comfort levels.
Note that star ratings bands/values differ with the location to account for local climate variations.