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New Emphasis on Solar PV and Electric Demand Flexibility in 2019

Rosemary Howley, Manager, Utilities & Education/Senior Energy Analyst
Rosemary Howley, Manager, Utilities & Education/Senior Energy Analyst

The 2019 Title 24 Building Energy Efficiency Standards have been approved by the California Energy Commission, and those standards will apply to all buildings going for permit on or after January 1, 2020. The biggest change in the 2019 Standards for new low-rise residential buildings is that the energy code will require both increased building energy efficiency, as in all past code cycles, plus a new separate compliance component for solar photovoltaics (PV) and electric demand flexibility. Essentially, residential electric demand flexibility involves ways to store energy during off-peak hours for use during on-peak hours to reduce the loads on California’s electric grid. One important demand flexibility example would be to install high-capacity batteries to save electricity generated by solar PV during the day, so that it can be used after the sun goes down.

New Performance Method Compliance Requirements

As you may have heard in the news, solar PV is a requirement for new homes complying with the prescriptive method, and almost all new homes will need solar PV installed to comply with the 2019 Standards whether they comply prescriptively or using the performance method. For new homes complying using the performance method, there will be separate compliance requirements for “Building Energy Efficiency” versus “PV plus Flexibility”. If a building is especially energy efficient, then those energy-savings can be an energy compliance credit that might allow a smaller PV system. Alternately, if a project includes solar PV plus a 5 kWh or larger battery storage system, then that extra electric demand flexibility from the batteries becomes an energy compliance credit that could trade off against high performance building envelope features like HERS QII. Prescriptively compliant solar PV systems on their own do not provide any performance energy compliance credits for building energy efficiency. This is a change from the 2016 Standards that allow PV credit to trade-off against building energy efficiency measures.

Another change is that the performance standard design energy budgets and proposed energy use will be shown on the compliance documents as Energy Design Ratings (EDR) that show how the building energy use ranks on a scale of zero to 100. Zero EDR equals a zero TDV energy home, while 100 EDR represents the TDV energy use of a 2006 International Energy Conservation Code (IECC) home. The 2006 IECC residential energy code is used in some other parts of the United States, but it is not as stringent as California’s Title 24 Energy Standards, so the California EDR requirements for new homes are likely to be much less than 100. The attached graphic shows an example of separate standard and proposed design EDRs for building energy efficiency versus PV plus flexibility, and how a Final EDR Score is calculated by subtracting the PV plus flexibility score from the building energy efficiency score.

2019 Title 24, Part 6: Energy Design (EDR) Compliance for New Construction

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New for 2019 Battery Storage Compliance Credit

Battery storage is a promising new compliance option to increase electric demand flexibility. Installing high capacity batteries as part of the electrical system for a home will allow some reduction in installed PV and also give trade-offs against building energy efficiency measures. It is not clear yet how much compliance credit they offer because the performance method software standard and proposed design rules have not yet been published. However, early test studies show that 5 kWh or larger battery storage installed with the standard solar PV could allow significant trade-offs for some of the high performance building envelope efficiency measures that are part of the standard energy budget. High-capacity batteries are likely to have high first costs, but they may be an attractive option for certain homes.

Solar Water Heating is Still a Compliance Credit

Solar thermal water heating is another renewable energy efficiency measure that has been an option in the Title 24 Energy Standards since the early days of our state energy code, and it is still available to reduce nonrenewable energy use for home hot water. Unlike solar PV, solar water heating can be used to trade-off against other building energy efficiency components. Solar water heating may also reduce the size solar PV system needed. Solar water heating doesn’t get as much press as solar PV, but it can be an excellent compliance credit for projects with high water heating energy use.

More News to Come!

The California Energy Commission is still working out some of the details about implementing the new solar PV and electric demand flexibility rules, especially regarding the computer performance method compliance software. However, we here at Gabel Energy are following this closely. We will keep you informed, and we will be ready to help you comply with the new standards when the time comes!

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