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City of San Mateo Municipal Code.

23.24.060 Local Amendment Regarding All-Electric Buildings or Energy Efficiency Standards for Low-Rise Residential Buildings with 100% Affordable Units.

(a) All-electric low-rise residential buildings that consist of 100% affordable units are required to meet the established energy efficiency standards in Subchapter 8, "Low-rise Residential Buildings – Performance and Prescriptive Compliance Approaches," of the 2019 state Energy Code.

(b) Mixed-fuel low-rise residential buildings that consist of 100% affordable units shall comply with increased energy efficiency standards. Subchapter 8, "Low-rise Residential Buildings – Performance and Prescriptive Compliance Approaches," of the 2019 state Energy Code is amended to require increased energy efficiency standards in the performance and prescriptive compliance approaches as follows:

(1) Performance Approach: Section 150.1.b. "Performance standards" is amended to include the following performance standard for newly constructed mixed-fuel low-rise residential buildings that consist of 100% affordable units:

The Total Energy Design Rating calculated for the Proposed Design Building shall be at least 0.5 EDR points less than the Total Energy Design Rating calculated for the Standard Design Building.

(2) Prescriptive Approach: Section 150.1.c. "Prescriptive standards/component packages" is amended to include the following prescriptive standards for newly constructed mixed-fuel low-rise residential buildings that consist of 100% affordable units:

(A) Slab floor perimeter insulation shall be installed with an R-value equal to or greater than R10. The minimum depth of concrete-slab floor perimeter insulation shall be 16 inches or the depth of the footing of the building, whichever is less.

(B) The hot water distribution system shall be designed and installed to meet minimum requirements for the basic compact hot water distribution credit according to the procedures outlined in the 2019 state Energy Code Reference Appendices RA4.4.6.

(C) Central Fan Integrated Ventilation Systems. Central forced air system fans used to provide outside air, shall have an air-handling unit fan efficacy less than or equal to 0.35 W/CFM. The airflow rate and fan efficacy requirements in this section shall be confirmed through field verification and diagnostic testing in accordance with all applicable procedures specified in 2019 state Energy Code Reference Residential Appendix RA3.3. Central Fan Integrated Ventilation Systems shall be certified to the Energy Commission as Intermittent Ventilation Systems as specified in 2019 state Energy Code Reference Residential Appendix RA3.7.4.2.

(D) Energy storage or Solar Thermal. Either of the following shall be installed:

(i) A battery energy storage system with a capacity equivalent to the PV system shall be installed. The system shall have automatic controls programmed to have the ability to charge anytime PV generation is greater than the building load and discharge to the electric grid during the highest priced time of use hours of the day , OR

(ii) A solar water heating system with a minimum solar savings fraction of 0.20.