Module Four of the National Construction Code Training Program focuses on understanding energy efficiency provisions for class 2 to 9 buildings, emphasizing the BCA's objectives to reduce operational energy use without compromising comfort. It outlines the principles of energy efficiency regarding building services and the structure of the National Construction Code (NCC), alongside historical changes made since the early 2000s for compliance in building energy performance. The module details three mandatory performance criteria aimed at enhancing energy efficiency and minimizing greenhouse gas emissions in buildings.