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
Battery storage systems provide benefit to the utility grid by serving the primary functions of daily charge and discharge cycling for the purpose of load shifting, maximizing solar self-utilization, and grid harmonization. This proposed submeasure would modify the battery storage system compliance option that exists under 2019 Title 24, Part 6 to align the code with technology performance improvements for battery storage systems, to ensure that battery control systems contribute value to owners and the utility grid, and to improve the enforcement and verification of battery storage system requirements.
HPWH Load Shifting
Load shifting heat pump water heaters (LSHPWHs) are designed to operate in response to signals from utilities or third party aggregators to control operation of the HPWH while still providing consistent and reliable hot water to the occupants. The water heater may “load up” – use electricity at a time advantageous to the grid (such as during a midday solar peak) – to store extra energy in the water tank prior to the start of utility peak periods to allow the tank to satisfy subsequent peak period hot water loads without requiring any additional operation. Additionally, LSHPWHs may respond to critical grid events where signals (a “shed” command) are sent to the unit to pause operation for a given time period. This load shifting approach has value in minimizing the curtailment of excess renewables on the electric grid year-round, which is becoming an increasing issue as more renewables enter the California grid. The Statewide CASE Team has been involved in activities supporting the LSHPWH concept including modeling studies (Delforge and Larson 2018) and laboratory testing (Grant and Huestis 2018).
HVAC Load Shifting
Pre-cooling is an HVAC load shifting strategy in which the building is intentionally over-cooled early in the day when electricity rates are low. The thermal mass of the building is cooled down during these off-peak periods, and serves to gradually slow down warming of the space later during the on-peak period, minimizing or avoiding the need for cooling during the higher-cost peak periods. Since air-conditioning is the biggest contributor to peak energy use in most homes, moving it away from the peak period dramatically reduces peak kW, energy used during the peak period, and Time Dependent Valuation (TDV), which is the cost metric used by the State of California to evaluate the cost-effectiveness of Title 24, Part 6 code change proposals. However, pre-cooling would almost always involve an increase in site energy consumption. Optimization of pre-cooling, then, would require finding an acceptable balance between reduction of TDV, kWh penalties, and the overall impact on utility bills. During the 2019 code change cycle, pre-cooling was introduced as a compliance option eligible for a Demand Flexibility credit. It requires the installation of an Occupant Controlled Smart Thermostat (OCST, as described in Joint Appendix 5 (JA5)).The modeled impact credit is de-rated by 70 percent, because its reliability is so heavily determined by occupant behavior.
Home Energy Management
Home Energy Management Systems (HEMS) are a subcategory of home automation that provides homeowners with the ability to control energy consuming devices through programmed schedules, control logic based on occupancy sensors or other measurements, machine learning, utility signals, and/or remote access through smartphones. Home automation technologies, including those with HEMS capabilities, have become much more commonplace in recent years, providing services ranging from energy management to home security, entertainment, and convenience. Voice recognition technology has made interacting with such systems accessible and fun for homeowners at all levels of technical sophistication. A HEMS may either be a master system that controls and monitors all end uses, or a system that controls appliances, lighting, and/or plug loads. HEMS can reduce TDV through either direct energy use reduction (e.g. turning off lights and TVs in unoccupied rooms), or through load shifting (e.g. suspending operation of clothes dryers during high demand periods). Energy and peak demand savings can also be achieved by providing information and recommendations to occupants, allowing them to modify their behavior in an informed manner. Home energy management is a quickly expanding market that is likely to have a large impact on energy use in homes, particularly in end-uses such as plug loads and lighting, where there are few if any opportunities to receive credit for energy savings in Title 24, Part 6.
Measure proposals, supporting documents, and other outside references will be made public as they become available.
Round Two Utility-Sponsored Stakeholder Meeting Materials
- Presentation – March 19 – Single Family Grid Integration
- Single Family Battery Storage Systems Submeasure Summary – February 7, 2020
- Single Family Heat Pump Water Heater Submeasure Summary – February 11, 2020
- Single Family Pre-Cooling Submeasure Summary – February 13, 2020
- Single Family Home Energy Management Submeasure Summary – February 13, 2020
- Notes – March 19 – Single Family Grid Integration
Round One Utility-Sponsored Stakeholder Meeting Materials
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.