What is Title 24?

Title 24 contains the building standard codes for all residential and commercial buildings in California. The codes are a set of broad requirements for energy conservation and green design applied to structural, mechanical, electrical, and plumbing systems. Every three years an updated set of standards is published to incorporate the latest technology and methods that increase energy efficiency. The most recent set was published in 2019 and contains important updates that take effect Jan 1, 2020.

This set of standards is important as it begins to put greater emphasis on grid management and interoperability by specifying how buildings should communicate with the electric grid. The energy interface to the electric grid is now an essential part of the overall building design and efficiency. Title 24 contains its own nuances as to how smart grid resources and buildings that can manage power consumption or put power back into the grid need to operate.

In this blog we will look at the communications requirements for buildings for both residential and commercial applications in Title 24. For reference, all citations regarding residential requirements in this blog are from the 2019 Residential Compliance Manual portion of Title 24, and all citations regarding the commercial requirements are from the 2019 Nonresidential Compliance Manual. The general report, both manuals, and more information on Title 24 can be found in full here.

Managing the Smart Energy Grid

To best manage the demand for energy in California, buildings are broken into commercial and residential categories. When you think about it, the needs of family homes and apartments are quite different than large office spaces. The separation of requirements for the two building categories allows for each to contribute differently to managing grid power requirements and stability.

Commercial spaces have larger daytime lighting and heating demands with occupancy during the day. Residential spaces have lower daytime heating and lighting demands and are occupied during the morning and night.

Title 24 Residential Communications Requirements

One of the most important updates on the residential side of Title 24 is the implementation of the senate assembly bill requiring all new homes built after Jan 1, 2020 to have a certain amount of installed solar capacity (Chapter 7, Section 7-7). This is calculated with an equation dependent on factors like a residence’s climate and how much sun they are exposed to. Title 24 defers to CA Rule 21 when it comes to smart inverter communications.

Title 24 indicates that “battery system[s] shall have the capacity to discharge electricity into the grid upon receipt of a demand response signal from the local utility or a third-party aggregator.” It specifies in Appendix H that “DR controls must have the ability of communicating with the entity that initiates a DR signal by way of an OpenADR certified Virtual End Node (VEN).” (Appendix H, H-2) Beyond conformance to OpenADR for DR events, an Energy Storage System (ESS) must also “comply with all applicable requirements specified in Rule 21.” (Chapter 7, 7-16) With focus on PV and ESS generation at the residential level, California is setting clear expectations that in order to most effectively manage energy consumption, no building is too small to contribute.

Title 24 Commercial Requirements

The commercial building requirements in Title 24 set out a solar-ready provisional rooftop area for all new commercial developments that could eventually support a solar energy generation requirement. There is no current mandate to have a photovoltaic (PV) system on commercial buildings. As such, the commercial requirements are not specific regarding the protocols necessary for PV grid communication. If commercial buildings do use PV, and do not intend to sell energy back to the grid, there would not be communication protocol requirements. But if the commercial building PV installation would be connected to the grid and capable of inserting power into the grid, then clear guidelines for communication protocol requirements already exist in CA Rule 21.

Energy Storage Systems (ESS) are treated similarly in the commercial requirements. There is no explicit section on ESS for commercial buildings, and therefore no communication requirements are explicitly mentioned. However, CA Rule 21 does specify how communications will happen if a commercial building has storage that will discharge energy into the grid.

The most important communication requirement for commercial buildings is for DR events. The commercial requirements use Appendix D to specify that DR communications must be done with an OpenADR A or B profile. The two basic requirements for DR controls include:

  • Conformance to the OpenADR communication protocol to interpret and act on event and price signals
  • Implementation of load shedding hardware that can support signals over WiFi, Zigbee, BACnet, Ethernet, or hard wire

The Appendix clarifies that the VEN can be physically part of the Building Control System or can be cloud based and capable of communicating with the Building Control System. Subsections include considerations for thermostats, HVAC, and lighting. The requirement for large commercial buildings to have DR Control Systems that are reactive to OpenADR price and other event signals makes clear the value California places on coordinating large-scale usage of energy in commercial buildings with grid operations.

Creating an Interoperable Ecosystem

California’s goal is to create an interoperable grid ecosystem. Without effective ways to communicate information between Utilities and smart grid resources or the systems that control them, managing complex, dynamic energy landscapes are expensive if not impossible. It is a major step forward to see two mandates in CA requiring the use of industry communications standards. California wants to ensure that communication protocols to residential and commercial buildings are standardized so that the costs of implementing communications to manage customer DER assets are minimal. DR events for smart grid resources and DERs for both residential and commercial buildings are standardized using the OpenADR 2.0 protocol. This consistency is good. While the residential communications requirements are more focused on DERS like PV and energy storage, the commercial requirements focus on assuring standardized communications with EMS.

With the changing composition of the grid toward DER resources, it is imperative that load shedding and generating resources be controllable via communication protocols. Therefore, communication interoperability must be an important focus for utilities and vendors alike. Since California is a major market for any vendor of energy consuming or generating devices and systems – e.g., it is 50% of the solar PV market in the US – vendors all over the world are adopting the communications protocols required in California. This in turn creates a growing global eco-system of vendors and implementers that supply and implement the standardized communications specified in CA. This makes it much easier for utilities elsewhere to piggyback on the pioneering work in California. Title 24 sets the stage for the adoption of communication standards for residential and commercial buildings on a global scale.

What Does This Mean for Vendors?

We are being asked today by our vendor customers to help them understand the impact of Title 24 on their business as it relates to implementing standard communications protocols.  The answers are unfortunately not as clear as we would like to see. From an OpenADR perspective, vendors are required to do the following:


  • ESS must be able to accept a DR signal by way of an OpenADR certified VEN (Chapter 7, 7-14; Appendix H, H-2)
  • DR controls installed at the circuit level for HVAC equipment must meet complete requirements for DR thermostatic controls (Appendix H, H-4)
  • Energy Management Control Systems must comply with required thermostatic and lighting control functions in Title 24 (Appendix H, H-4)


  • Buildings without DDC to the zone level require single zone air conditioners and heat pumps to be DR thermostats, or OCSTs.
  • Buildings larger than 10,000 sq. ft. must be equipped with DR controls for indoor lighting systems
  • Electronic Message Centers that have a lighting load greater than 15kW must have demand responsive controls
  • IF DR controls are installed as part of the power distribution system, the controls must meet DR requirements
  • EMCS installed to perform lighting and control functions must meet DR requirements to be complaint with Title 24

For vendors of any DER (Solar PV, generators, ESS and potential EV charging) where energy will be sold back or otherwise injected into to the utility grid, Title 24 also mandates conformance to CA Rule 21. 

If changes to Title 24 affect your company’s need to conform to the OpenADR protocol, or even the IEEE 2030.5 protocol, then get in touch with our team and we can walk you through the requirements. Our team has trained hundreds of developers through our training classes and has created dedicated, OpenADR and SunSpec Alliance approved Test Tools for development and pre-certification efforts.