A lower EDR1 score represents lower source energy consumption. The EDR1 score is a metric of the proposed design source energy divided by the reference design source energy budget. An EDR1 score is calculated for the proposed design and a second EDR1 score is calculated for the standard design. The proposed design EDR1 must be equal to or less than the standard design EDR1.

An EDR2 score of zero represents a building that has zero-net-energy performance based on the TDV energy consumption, and an EDR2 score of 100 represents a building that is minimally compliant with the 2006 International Energy Conservation Code. The EDR2 score is a ratio of proposed design TDV budget to reference design TDV budget.

An Efficiency EDR2 and Total EDR2 score are calculated for the proposed design and a second Efficiency EDR2 and Total EDR2 score are calculated for the standard design. Compliance with EDR2 requires meeting two criteria:

• Proposed design Efficiency EDR2 must be equal to or less than standard design Efficiency EDR2. The EDR2 is established by the ratio of the standard design or proposed design space heating, space cooling,indoor air quality IAQ ventilation, water heating, self-utilization credit TDV energy consumption, and the reference design TDV energy consumption of the same end uses.
• Total EDR2 (Efficiency EDR2, plus PV/flexibility EDR2) of the proposed design must be equal to or less than the Total EDR2 of the standard design. The Total EDR2 is established by the ratio of the standard design or proposed design efficiency end uses plus interior lighting, appliances, cooking, plug loads, exterior lighting, and PV generation and flexibility measures TDV energy consumption and the reference design. TDV energy consumption of the same end uses.

The single-family residential building configuration is defined by the user through entries that include floor areas, wall areas, roof areas, ceiling areas, window areas, skylight areas, and door areas. The user also specifies performance characteristics such as R-values, solar heat gain coefficient (SHGC), solar reflectance, and thermal emittance are required inputs. Information about the orientation and tilt is also required for roofs, and exterior walls. Details about the HVAC and water heating systems, as well as any solar generation systems and battery storage, are also defined by the user. The user entries for all building elements should be consistent with the actual building design. If the compliance software models the specific geometry of the building by using a coordinate system or graphic entry technique, the data generated should be consistent with the actual building design.

The standard design building, from which the energy budget is established, is in the same location and has the same geometry as the proposed design, except the wall and window areas are distributed equally among the four cardinal directions (north, east, south, and west). For additions and alterations, the standard design shall have the same wall and fenestration areas and orientations as the proposed building. The details are described below.

The energy budget for the residential standard design is the energy that would be used by a building similar to the proposed design if the proposed building met the requirements of the prescriptive standards. The compliance software generates the standard design automatically, based on fixed and restricted inputs and assumptions. Custom energy budget generation shall not be accessible to program users for modification when the program is used for compliance or when the program generates compliance forms.

The basis of the standard design is prescriptive requirements from Section 150.1(c) of the Energy Code, Table 150.1-A. Prescriptive requirements vary by climate zone. Reference Appendices, Joint Appendix JA2, Table 2-1, contains the 16 California climate zones and representative cities. The climate zone is based on the zip code for the proposed building, as documented in JA2.1.1.

The following sections present the details of how the proposed design and standard design are determined. For many modeling assumptions, the standard design is the same as the proposed design. When a building has special features, for which the CEC has established alternate modeling assumptions, the standard design features will differ from the proposed design, so the building receives appropriate credit for its efficiency. When measures require verification by a Home Energy Rating System (HERS) rater or are designated as a special feature, the specific requirement is listed on the CF1R.

The reference design is calculated using the same inputs, assumptions, and algorithms as the standard design except for the following requirements:

• Air handler power. The air handler power is 0.8 watts per cubic feet of airflow per minute (W/CFM).
• Air infiltration rate. The air infiltration rate is 7.2 air changes per hour at 50 pascals of pressurization (ACH50).
• Cooling airflow. The air handler airflow is 300 cubic feet of airflow per minute per ton of cooling capacity (CFM/ton).
• Duct R-value. The duct R-value is R-8.
• Duct leakage rate. The duct leakage rate is modeled as a heating, ventilation, and air-conditioning (HVAC) distribution efficiency of 80 percent.
• Quality insulation installation (QII). QII is modeled as “Yes.”
• Wall construction. Climate Zones 2–15 have 2x4 R-13 walls. Climate Zones 1 and 16 have 2x6 R-19 walls.
• Roof/ceiling construction. Climate Zones 2–15 have R-30 ceiling. Climate Zones 1 and 16 have R-38 ceiling. No climate zones include radiant barriers or cool roofs.
• Raised floor construction. Climate Zones 2–15 have 2x10 R-19 floors. Climate Zones 1 and 16 have 2x10 R-30 floors.
• Slab edge insulation. Climate Zones 1 and 16 include R-10 insulation 24 inches deep.
• Window U-factors. Climate Zones 2–15 have 0.65 U-factor. Climate Zones 1 and 16 have 0.35 U-factor.
• Window SHGC. All windows have 0.4 SHGC.
• Window area. When the window area is below 18 percent of the floor area, the reference design has the same area as the proposed design. Above 18 percent, the reference design has 18 percent.
• HVAC equipment efficiencies. HVAC equipment meets National Appliance Energy Conservation Act (NAECA) requirements in effect in 2006 such as 78 percent AFUE for gas central furnace, and 13 SEER for central air conditioning.
• Water-heating efficiency. Water heating modeled as a 40-gallon storage water with a 0.594 energy factor (EF) if gas or a 0.9172 EF if electric.
• Appliance and plug-load energy use and internal gains. Energy use and internal gains for appliance and miscellaneous plug loads are modeled as specified the ANSI/RESNET/ICC 301-2014 Standard.

The PV requirements are applicable to newly constructed single-family residential buildings. PV system details are from PVWatts, which is a web application developed by the National Renewable Energy Laboratory. See Appendix F for more information.

Standard Design

The standard design PV system (based on California flexible installation [CFI] assumptions) is sized to generate enough electricity to offset the entire annual electricity consumption for a mixed-fuel building that meets all the 2022 prescriptive requirements.

The compliance summary tab in CBECC-Res provides energy consumption information for the building, including photovoltaic and battery systems (Figure 2: Energy Use Details).

For PV sizing calculations, the software assumes the CFI orientation 170 degrees, standard efficiency for modules, inverter efficiency of 96 percent, fixed tracking, standard (excluding horizon) shading, roof tilt of 22.61 degrees (5:12 pitch), and annual solar access percentage of 98 percent.

Proposed Design

The proposed PV system is sized to offset the entire annual electricity consumption of the proposed design.

For PV sizing calculations, the software includes user-defined values for:

• Array orientation, including CFI1 (installation of 150–270 degrees, CFI2 (installation of 105-300) or the actual orientation.
• Module type, including standard (for example, poly- or monocrystalline silicon modules), premium (for example, high-efficiency monocrystalline silicon modules with anti-reflective coatings), or thin film (in other words, low efficiency such as 11 percent).
• Inverter efficiency.
• Array tilt in degrees or roof pitch, or CFI1 or CFI2 (installation up to 7:12).
• Array tracking type including fixed, single-axis tracking, and two-axis tracking.
• Annual solar access percentage, excluding horizon shading, of the modules.

The PV size is reported in kWdc.

Figure 2: Energy Use Details

^{Source: California Energy Commission}