Select Page

Occupant Controlled Smart Thermostat (Limited Modifications to Joint Appendix 5)

2016 Title 24 CASE Topics

Measure Overview

The proposed changes will clarify the requirements in Title 24 Joint Appendix 5 – Technical Specifications for Occupant Controlled Smart Thermostats (JA5). The Utility Team is not proposing changes to when OCSTs are required.[1] The specific revisions to JA5 are described below:

  • General Clean-up: Generally speaking, the language in JA5 was difficult to understand. The Utility Team offered revisions to sections of JA5 to help improve clarity and readability without modifying the requirements.
  • Clarify Definitions Communications Interfaces: Definitions for physical and logical communication interfaces were not clear. The proposed revisions aim to more clearly define the physical and logical interfaces. The physical communication interface is the physical connection that enables receipt of signals. The logical communication interface is the information model and its messaging protocol used for representation and interpretation of signals received by the OCST.
  • Clarify Requirements for Physical Communication: The requirements for the physical communication interface were ambiguous. The proposed revisions clarify that OCSTs shall be capable of connecting to either a Wi-Fi network and/or a Zigbee network. Manufacturers may choose to include additional physical communication interfaces, but at a minimum the OCST must be capable of communicating via Wi-Fi or Zigbee. The revised language also clarifies that the physical communication interface shall be capable of both receiving and sending information. This clarification is necessary because if a customer actually wants to sign up for a DR program, bi-directional communication is necessary. The customer needs to be capable of receiving a signal so demand shed is initiated. To manage the demand response event appropriately, the utility (or other entity sending the signal) needs to receive information from the customer so they can verify that the signal was received and if/how the customer is responding to the signal.
  • Clarify Logical Communication Requirements: The requirements for the logical communication interface were ambiguous. The proposed revisions clarify that OCSTs must be compliant with either OpenADR 2.0 or Smart Energy Profile (SEP) 1.1 . Both of these standards are open-based standards that are listed on the Smart Grid Interoperability Panel (SGIP) Catalog of Standards (CoS).   Manufacturers may choose to use an additional communication protocol, but at a minimum the OCSTs must be compliant with either OpenADR2.0 or SEP 1.1. The proposed language also clarifies that applicants should check with the local utility for guidance on which logical communication protocol OCSTs in their service territory should use.
  • Clarify Requirements for Thermostats using Expansion Ports: The proposed language clarifies that if the OCST uses an expansion port, at the time of permitting the expansion port must be populated with the removable communication module. That is, at time of permitting, the OCST must be capable of the required communications. If desired, the building occupant can remove the communication module from the OCSTs after the certificate of occupancy is issued. The existing language could have been interpreted that if the OCST used an expansion port, the OCST did not have to be installed with the required communications capabilities. The revised language eliminates this loophole.
  • Clarify Requirements for Demand Responsive Control: The intention of the Standards is that OCSTs be a Demand Responsive Control that is capable of initiating a response to any Demand Response Signal for the appropriate Demand Response Period. The existing language in JA5 could have been interpreted that an OCST only needed to be responsive to price signals. The proposed language clarifies the original intent of the standards, and further clarifies that a price signal is a type of Demand Response Signal.
  • Eliminate Requirements for Demand Response Event Delay: Existing language states that if the logical communication protocol does not contain restoration delay logic, the OCST itself must have the capability of randomizing event restoration. This requirement is not precise and leaves significant work for the code enforcement body to determine if an OCST is in compliance. The Utility Team is recommending that requirements for event restoration delay be deleted. Ultimately, the utility, or the entity responsible for grid operation, is accountable for ensuring loads are come back online after an event. OpenADR 2.0a, OpenADR 2.0b and SEP 1.1 have a mandatory requirement to accommodate event restoration delay signals, but guidance on how the delay will occur come from the utility, or entity responsible for the grid operation. The Utility Team prefers that event restoration responsibilities fall with the utility not the OCST itself.
  • Add Requirements for Default Restart Settings and Automatic Rejoin: This Utility Team recommends adding requirements that ensure the OCST restores correctly after it loses power, restarts, or loses connection to the signaler. The default restart settings requirement states that if the OCST loses power or re-starts that when the device comes back online the device shall restore to the most recently programmed settings. The automatic rejoin requirements state that if physical and/or logical communication is lost, the OCST will trigger an automatic rejoin function to restore the communication connection.

[1]   The 2013 Title 24 Standards include a mandatory requirement that nonresidential buildings with unitary, single zone heating and cooling systems be equipped with OCSTs if the building is not controlled by an energy management control system (EMCS). For residential buildings, applicants have the option of installing more efficient lighting and OCSTs instead of implementing the solar-ready provisions.

Stakeholder Meeting

Several stakeholder meetings and CEC staff workshops were held regarding the Nonresidential HVAC Economizer Modifications building energy efficiency topic. The list of past meetings and hearings can be found here. If you would like to receive email updates on this CASE topic, click the link below.