Summary of Correspondence with the Senior Mechanical Engineer of the California Energy Commission, Danny Tam, Regarding the “Gas NotAvailable” Setting in Title 24 Code Software.
On Thursday, February 25, 2021, Danny Tam of the CEC corresponded with Sean Armstrong of Redwood Energy on questions regarding modeling heat pump water heaters, which centered on the topic of how to answer the software prompt of whether natural gas is “available” to the building.
The guidance and citations shared by Danny Tam (see Correspondence on the next page) are summarized in the following two points:
1. On p.73 of the 2019 Building Energy Efficiency Standards “NATURAL GAS AVAILABILITY” is defined: “For newly constructed buildings, natural gas is available if a gas service line can be connected to the site without a gas main extension.” The CEC does not define “gas . ain extension,” and defers to the Utilities.
2. PG&E defines a gas “Main Line Extension” as an “Extension of electric or gas service from the main energy supply line to the customer’s facility.” A “supply line to the customer’s facility” is called a “Service Lateral” in language of Architects and Engineers.
Discussion
The CEC does not have an independent definition of what constitutes a “gas main extension,”nor does it define whether a “site” is a building or a parcel, but Title 24 code regulates onlybuildings.
The Senior Mechanical Engineer of the CEC directs interested parties to a definition provided by PG&E. PG&E’s definition describes a Gas Service Lateral to a “customer’s facility,” which is more clearly speaking to a building, not to the parcel. Utilities deliver to meters that are nearor attached to buildings, not to the parcel boundary.
Consequently it is reasonable and appropriate for a Certified Energy Analyst to select “Gas Not Available” in the Title 24 software prompt when a Gas Service Lateral is not being extended to the parcel the building sits upon, nor to the building. With more than 50 cities in California banning gas in new construction as of March of 2022, and the California Air Resources Board announcing a new rule to end the sale of all gas appliances by 2030, a CEA will have to get comfortable with the relatively new practice of choosing the “Gas Not Available” setting in Title 24 software.
The result of choosing “Natural Gas Not Available” the first tab of the CEC Title 24 software is the software sets Propane as the only Available fuel. Propane boilers’ fuel costs are consistently higher than various heat pump water heater’s electricity costs, and a Title 24 model shows positive Compliance for heat pump boilers. This is true even without a .25-.35 solar fraction that is in the Prescriptive Code for all multifamily central water heaters.
Redwood Energy has led the design of more than 20,000 units of Zero Net Energy, all-electric affordable housing, and 200 all-electric market rate residences.
