This CASE Report will evaluate the ability of load shifting technologies to reduce grid impacts. Single family targeted applications include: batteries, HVAC load shifting, heat pump water heater load shifting controls, and home automation technologies that have the potential to coordinate the operation of multiple load-shifting measures.
In addition, the Statewide CASE Team will review potential residential demand response cleanup activities identified in the 2019 Final Demand Response Clean-up CASE report. Demand flexibility measures are very important as a means to integrate buildings with a changing electrical grid where challenges are created by increasing photovoltaic and wind generation coupled with growing demand. These grid harmonization measures would all be compliance options for the residential sector.
Battery Storage Systems
Single Family Battery Storage Systems describes the battery storage system installed within single family residential homes. Primary functions of the battery storage system include:
- Daily cycling for the purpose of load shifting
- Maximized solar self-utilization
- Grid integration
The battery storage system implements these functions by charging the battery from a solar photovoltaic (PV) system when there is limited electrical load at the building and discharging when building load exceeds generation.Additional controls strategies allow the battery system to adjust discharge time windows to better respond to peak demand periods when the cost of electricity is high.
Battery storage is available as a compliance credit in the performance compliance method. Battery storage is integrated in the latest version of 2019 CBECC-Res in accordance to Joint Appendix 12(JA12) of the 2019 Title 24 Reference Appendices. JA12 defines compliance qualification requirements for battery systems installed in conjunction with on-site photovoltaic systems. Compliance qualifications include safety, performance, battery controls, interconnection, and enforcement requirements.
Load Shifting Heat Pump Water Heater
The residential heat pump water heater (HPWH) load shifting measure will build on work that is currently underway in finalizing the draft JA13 Appendix (Qualification Requirements for Heat Pump Water Heater Demand Management Systems) and implementing the load shifting HPWH capabilities into the CBECC-Res residential compliance software. The outcome of this work (expected mid-year 2020) may influence the final 2022 proposal. The current proposal is based on the Advanced Load Up strategy, whereby the water heater storage volume may be heated beyond the user set point (typically 10-15°F above) normal setpoints during the middle of the day (when photovoltaic generation resources are at their peak) on a daily basis to help mitigate renewables curtailment. The scope of the effort includes:
- Proposed modifications to the current draft JA13 Appendix.
- Estimation of Advanced Load Up energy and TDV impacts
- Recommendation of HERS inspection requirements in the Residential Appendices.
Pre-Cooling and Thermostats
- This measure will update the voluntary compliance options for Pre-Cooling. The qualifying criteria for this measure will be defined in a proposed new Joint Appendix 14. This will continue to provide credit as a “Demand Response Flexibility” measure, but with the following modifications:
- Revisit CBECC-RES assumptions for factors—such as optimal pre-cooling start time, optimal pre-cooling period temperature setpoint, regular temperature setpoints and schedules, system sizing, and thermal mass—used to establish credit.
- Develop criteria for thermostats that are eligible for this credit:
- No longer require an Occupant-Controlled Smart Thermostat with demand response capabilities.
- Require a set of features for thermostat User Interface and Display, and Required Functional Behavior, designed to improve usability for pre-cooling. These features are to be determined.
- Require a set of default optimal schedules, specific to climate zone, to be shipped by the manufacturer/distributor or set by the installing contractor, potentially with associated acceptance tests.
- Develop a CEC certification process, potentially with associated labeling to assist in inspections.
- Update the current 70% “derating” factor currently imposed, to reflect improved usability and a improved behavioral analysis.
This sub-measure also includes an additional separate measure:
- Consider providing additional compliance options for additional Smart Thermostat features, to be determined.
Home Energy Management
This measure will provide a clear definition and qualifying criteria for Home Energy Management Systems (HEMS) based on the Smart Home Energy Management (SHEMS) specifications defined by ENERGY STAR. Language related to the solar zone credit when a Home Automation System is installed in combination with a smart thermostat will be replaced with HEMS, which is the more common industry term for systems that specifically control energy use in homes. Additional definitions for smart thermostats will also be included to clarify requirements for demand response, scheduling, advanced control logic, and other functionalities.
Measure proposals, supporting documents, and other outside references will be made public as they become available.
Give Us Your Feedback
The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.
Use the form above to provide feedback on this measure.