Title 24 Part 6, or what is commonly known as the California Building Energy Efficiency Standards, is the defining document for complying with California's energy code. It can be complex and understanding the nuances and exceptions that apply to each project can be challenging.
Let’s look at the mandatory requirements and then compare the Prescriptive and Performance paths to help you make the best decision for your project.
Mandatory requirements are the easiest to understand. The mandatory requirements must be met, there are no paths around them. There are, however, exceptions to almost every mandatory requirement that may or may not apply to your project. These exceptions can save significant project costs so working with a good energy modeler and design team that can provide information on project specific options is very important. Some of the more notable requirements are shut off devices on lighting (wall switches) and continuous insulation on metal framed buildings.
Most of the energy code confusion occurs in the compliance paths. A project can decide to comply prescriptively or via performance path.
Prescriptive compliance requires that a project fulfill specific requirements for the envelope, lighting, HVAC, domestic hot water and several covered processes. This can lead to an easier design path but most often leads to higher total construction costs. Meeting the prescriptive requirements means that the project receives no credit for systems that outperform the prescriptive level of compliance.
For example, LED lighting often exceeds the prescriptive requirements but no credit is available to install a lower performing wall or windows for example. The prescriptive requirements for the windows, walls, roofs, HVAC, etc must be satisfied. This is where a performance path can greatly benefit the project.
The performance path allows you to take the LED credit from the above example and apply it to a lower performing wall and/or window. This can reduce project cost substantially.
The prescriptive window requirements alone are very difficult to satisfy, especially if the window is metal framed. But applying the lower W/sf credit we received from using LEDs can allow us to select a window that is below the prescriptive requirement. This all depends on how many windows we have and how much credit we will receive from the LEDs.
Okay, if you got all of that, you might expect that all projects should go performance. Unfortunately, the energy modeling to comply via performance path takes a significant amount of time. It's important to educate the project owner and developer on this total cost benefit so they are comfortable paying for higher energy modeling costs in order to arrive at a lower total cost.
If you have any questions on Title 24 Part 6 please reach out. We are happy to help!