There are three methods that are permitted in order to meet specified HVAC energy standards/codes.
A. Component performance or prescriptive method. In this procedure, the maximum permissible overall thermal performance values Uo of the building components are prescribed. The actual values are calculated by formulas to confirm compliance with the prescribed criteria.
B. System performance method. In this procedure, the whole building envelope is considered a system whose thermal performance must meet prescribed standards.
C. Energy cost budget method (ECB). In this procedure, the proposed building energy use and cost is determined and compared to the scribed values for compliance.
Heating Design Requirements