2025 Single-Family Residential Alternative Calculation Method Reference Manual: for the 2025 Building Energy Efficiency Standards

The California Energy Commission’s (CEC) 2025 Building Energy Efficiency Standards for residential and nonresidential buildings allows compliance by either a prescriptive or a performance method. Performance compliance uses computer-modeling software to trade-off efficiency measures. Performance compliance is the most popular compliance method because of the flexibility it provides in the building design.

Compliance software must be certified by the CEC using the rules established for modeling software. This document establishes the rules for creating a building model, describes how the proposed design (energy use) is defined, explains how the standard design (energy budget) is established, and reports on the Performance Compliance Certificate. This document does not specify the minimum capabilities of vendor-supplied software. The CEC reserves the right to approve vendor software for limited implementations of what is documented in this manual.

This Single-Family Residential Alternative Calculation Method Reference Manual explains how the proposed and standard designs are determined. The explanation for multifamily residential building proposed and standard designs are described in the Nonresidential and Multifamily Alternative Calculation Method Reference Manual.

The 2022 compliance manager is the simulation and compliance rule implementation software specified by the CEC. The compliance manager, called California Building Energy Code Compliance Residential (CBECC-Res), models all the regulated energy performance features affecting the energy compliance of a building.