This chapter describes how the proposed design is modeled and how the standard design is established.
The building configuration is defined by the user through entries for floor areas, wall areas, roof and ceiling areas, fenestration areas, and door areas. Each is entered along with performance characteristics such as U-factors, SHGC, thermal mass, etc. Information about the orientation and tilt is required for walls, fenestration and other elements. The user entries for all of these building elements are consistent with the actual building design and configuration. If the compliance software models the specific geometry of the building by using a coordinate system or graphic entry technique, the data generated is consistent with the actual building design and configuration.
For newly constructed buildings, the standard design building, from which the energy budget is established, is in the same location and has the same floor area, volume, and configuration as the proposed design, except that wall and window areas are distributed equally between the four main compass points, North, East, South and West. For additions and alterations, the standard design shall have the same wall and fenestration areas and orientations as the proposed building. The details are described below.
The space conditioning energy budget for the residential standards is the energy that would be used by a building similar to the proposed design if the proposed building met the requirements of the prescriptive standards. The process of generating the standard design is performed automatically by the compliance software, based on fixed and restricted inputs and assumptions. The process of custom budget generation shall not be accessible to program users for modification when the program is used for compliance purposes or when compliance forms are generated by the program.
The basis of the standard design is prescriptive Package A (from §150.1(c) of the standards, Table 150.1-A). Package A requirements (not repeated here) vary by climate zone. Reference Joint Appendix JA2, Table 2-1, contains the 16 California climate zones and their representative city. The climate zone can be found by city, county and zip code in JA2.1.1.
The following sections present the details on how the proposed design and standard design are determined. For many modeling assumptions, the standard design is the same as the proposed design. When a building has special features, for which the Commission has established alternate modeling assumptions the standard design features will differ from the proposed design so the building receives appropriate credit for its efficiency. Typically, these measures require verification. Alternate features, such as zonal control, are documented as Special Features on the Certificate of Compliance. Verified features are also documented on the CF1R.