With either the prescriptive or performance compliance paths, there are mandatory requirements that always must be met. Mandatory requirements include infiltration control, lighting systems, minimum insulation levels, and equipment efficiency. The minimum mandatory levels are sometimes superseded by more stringent prescriptive or performance requirements.
The prescriptive approach (composed of requirements described in Chapters 3, 4, 5, 6, 7, 10, and 11) requires each component of the proposed building to meet a prescribed minimum efficiency. The approach offers little flexibility but is easy to use. If the design fails to meet even one requirement, then the system does not comply with the prescriptive approach. In this case, the performance approach provides more flexibility to the building designer for choosing alternative energy efficiency features.
A. Building Envelope. The prescriptive envelope requirements are the required thermal performance levels for each building component (walls, roofs, and floors). These requirements are described in Chapter 3. The only flexibility is if portions of an envelope component do not meet a requirement, a weighted average of the component can be used to demonstrate compliance. The stringency of the envelope requirements varies according to climate zone and occupancy type.
B. Mechanical. The prescriptive mechanical requirements are described in Chapter 4. The prescriptive approach specifies equipment, features, and design procedures but does not mandate the installation of a particular HVAC system.
C. Indoor Lighting. The prescriptive lighting power requirements are determined by one of three methods: the complete building method, the area category method, or the tailored method. These approaches are described in Chapter 5. The allowed lighting varies according to the requirements of the building occupancy or task requirements.
D. Outdoor Lighting. Outdoor lighting standards are described in Chapter 6, setting power limits for various applications such as parking lots, pedestrian areas, sales canopies, building entrances, building façades, and signs. The Energy Code also set minimum requirements for cutoff luminaires and controls. Detailed information on the outdoor lighting power allowance calculations is in Section 6.4.
The performance approach (Chapter 12) allows greater flexibility than the prescriptive approach. It is based on an energy simulation model of the building.
The performance approach requires an approved computer compliance program that models a proposed building, determines the allowed energy budget, calculates the energy use of the building, and determines when it complies. Design options such as window orientation, shading, thermal mass, zonal control, and building configuration are all considered in the performance approach. In addition to flexibility, it helps find the most cost-effective solution for compliance.
The performance approach may be used for:
•Envelope or mechanical compliance alone.
•Envelope and mechanical compliance.
•Envelope and indoor lighting compliance.
•Envelope, mechanical, and indoor lighting compliance.
Indoor lighting compliance must be combined with envelope compliance. The performance approach does not apply to outdoor lighting, sign lighting, exempt process load, some covered process loads (for example, refrigerated warehouses), or solar-ready applications.
Time-dependent valuation (TDV) energy and Hourly Source Energy (HSE) are the “currency” for the performance approach. TDV energy considers the utility costs associated with the type of energy (electricity, gas, or propane) and the time when it is saved or used. Energy saved when California is likely to have a statewide system peak is worth more than when supply exceeds demand. Appendix JA3 of the Reference Appendices has more information on TDV energy. Like TDV, HSE considers the type of energy (electricity, gas, or propane), but is based on the amount of long-term depletable energy resources used to meet the energy demand of the building in each hour. HSE values are very similar to the long-term hourly utility greenhouse gas emissions and a strong metric for encouraging building decarbonization.
See Chapter 12 if the performance approach will be used for additions and alterations.
The CEC has a formal process for certification of compliance options for new products, materials, designs, or procedures that can improve building efficiency. Section 10-109 allows the introduction of new calculation methods and requirements that cannot be properly accounted for in the current approved compliance approaches. The compliance options process allows the CEC to review and gather public input about the merits of new compliance techniques, products, materials, designs, or procedures to demonstrate compliance for newly constructed buildings and additions and alterations to existing buildings.
Approved compliance options encourage market innovation and allow the CEC to respond to changes in building design, construction, installation, and enforcement.