Prescriptive Title 24 energy compliance
The prescriptive requirements are organized by packages. The prescriptive path is simple but inflexible.
Performance Title 24 compliance
The performance energy compliance method is an alternative to the prescriptive requirements. Approved computer programs model a house with the features of Package D to determine the space conditioning and water heating budgets.
The performance path allows trade-offs between different building components (wall, roof, windows, infiltration, equipment, etc.), as long as the overall building energy consumption is shown to be within the maximum allowable values of kBTU/sq. ft.