01Existing, altered or new
Energy documentation for work on an existing building generally sorts each component into existing (unchanged), altered (changed) or new (added). Requirements usually attach to altered and new components, while unchanged existing components may not need to be upgraded. How the categories are applied depends on the code cycle and the scope, so clear drawings are essential.
02Addition alone or existing-plus-addition
For eligible single-family additions, the CEC manual describes addition-alone and existing + addition + alterations performance approaches. The applicable addition rules are not automatically identical to every newly constructed building requirement. A combined approach requires appropriate existing-building inputs; any claimed improvements must follow the edition-specific modeling, evidence and verification rules.
03Alterations can trigger requirements
Some alterations bring specific requirements even without an addition: replacing HVAC equipment, extending or replacing ducts, replacing windows, reroofing, changing water heaters or altering lighting. Some of these may require installer certification or field verification. Ask your contractor and reviewer what applies before committing to equipment or products.
04Document existing conditions carefully
Useful records include:
- +Photographs of HVAC and water heater nameplates
- +Window types, frame materials and approximate sizes
- +Known insulation in attics, walls and floors
- +Approximate age of the original construction and prior additions
- +Drawings that clearly mark existing, altered and new elements
05Practical guidance
Where existing conditions are unknown, state assumptions on the plans and discuss them with the preparer. Investigating before documentation, such as checking attic insulation, is usually easier than revising later. This is planning context only; confirm how your jurisdiction applies alteration requirements.
06A hypothetical example
Suppose an owner adds a 400-square-foot family room and also replaces an old furnace. The team first separates the new conditioned area from the equipment alteration. It then compares any eligible addition-alone and combined performance paths under the applicable CEC rules, without assuming that the furnace replacement automatically earns a credit. Photos of nameplates, documented insulation and the current window information help establish what can actually be modeled. Proposed upgrades must be identified on the coordinated plans rather than inserted as uncommitted assumptions. Evidence and any required verification for existing features should be discussed before selecting the path.