This chapter explains the performance method of complying with the Building Energy Efficiency Standards (Energy Standards). The performance method provides maximum flexibility to trade off the energy performance of different building components to achieve compliance. For new construction, the energy budget is expressed in terms of the Energy Design Ratings (EDR), which are based on source energy and time-dependent valuation (TDV) energy. The EDR is a score from 0 to 100, where 0 represents a building that has zero net energy consumption based on the TDV energy consumption and 100 represents a building that meets the 2006 International Energy Conservation Code. This is the same criteria for a score of 100 for the National Home Energy Rating System. Energy Commission-approved compliance software programs calculate an EDR for the building (proposed efficiency) and compare it to the energy budget (standard efficiency). Approved compliance programs also calculate an EDR for proposed photovoltaic (PV)/demand flexibility and compare it to the standard PV/flexibility budget.
Energy Design Rating 1 (EDR1) is based on hourly source energy. Energy Design Rating 2 (EDR2) is based on TDV energy and has two components, the Energy Efficiency Design Rating and the Solar Electric Generation and Demand Flexibility Design Rating. The Total Energy Design Rating accounts for both the Energy Efficiency Design Rating and the Solar Electric Generation and Demand Flexibility Design Rating. The proposed building must separately comply with the Source Energy Design Rating (EDR1), Energy Efficiency Design Rating (Efficiency EDR2) and the Total Energy Design Rating (Total EDR2).
The standard efficiency includes water heating, space heating, space cooling, indoor air quality (IAQ) fan energy, and solar generation. Energy use from lighting and appliances is not eligible to be traded off.
The Energy Commission-approved compliance software programs calculate space-conditioning and water-heating energy use in accordance with a set of rules. Modeling capabilities are in the Residential Alternative Calculation Method (ACM) Reference Manual. All approved software programs use the California simulation engine to simulate the energy use, and the same report generator to create the certificate of compliance (CF1R), as the public domain program, California Building Energy Code Compliance - Residential (CBECC-Res). Approved software vendors have can create their own user interface, documentation, and additional forms. Each approved program is required to have a compliance supplement with information on how to use the software, as specified in the ACM Approval Manual.
A discussion of the performance method for additions and alterations is in Chapter 9.