TITLE 24 DOCUMENTATION
Title 24 part 6 is the section of California Building Code which details the necessary elements for designing residential that meet the California building energy efficiency standards.
It includes components like window replacement, new HVAC systems, plumbing systems, electrical systems, additions or alterations, insulation, or any new buildings assemblies for residential projects.
There are two primary ways of showing that your project meets energy code - "prescriptive or performance"
This is the standard of building design that is used throughout California and varies based on what climate zone the project is located in. When using this method of compliance the builder or installer is required to meet the efficiency standards for that climate zone. This can apply to things like furnace change-outs, replacing a few windows, or even building an entirely new residential home or building. When this method is used, each aspect of the design must exactly match the prescriptive requirements which means that there is no flexibility allowed in the design. Using the prescriptive approach can be very useful for smaller alterations as it speeds the process up and doesn't require as much documentation as the performance approach.
This method is commonly used when the designer or architect wants more control over how the project is built. When using the performance approach designers can pick and choose the energy efficiency upgrades that they want installed in the building. If they choose to install a high efficiency water heater they may be able to reduce the amount of insulation in the walls. It's a balancing act. As long as the building meets or exceeds the required compliance margin, it will meet energy code standards. However if it falls short of the requirements, other measures will need to be added into the design to get it into compliance. This approach takes longer to model but is often the preferred method when it comes to optimized design and value engineering.
California has sixteen individual climate zones which your Energy Consultant is required to understand to accurately model your home or building. The building science is affected by the amount of moisture in your climate zone. The climate zone of your property determines whether you are heating or cooling focused as well as the amount of weather proofing necessary.