California-Title 24 Calculations

California has the largest population and economy among all US states, and the second highest energy consumption after Texas. However, according to the US Energy Information Administration, the energy consumption per capita in California is among the lowest in the USA. In great part, this has been possible thanks to the Building Energy Efficiency Standards found in Title 24, Parts 6 and 11, of the California Code of Regulations (CCR).

Actually, Title 24 contains all the California state building codes, covering areas like mechanical equipment, electrical wiring and plumbing installations. However, the construction industry associates Title 24 with energy performance requirements for buildings. When architects and engineers refer to Title 24 calculations and forms, they are actually talking about the California Energy Efficiency Standards Compliance Forms.

The Title 24 forms must be submitted to the building department as part of the project approval process in California. These forms are used to document energy compliance in project designs, and they are required for building permits. The Title 24 energy requirements apply for new homes, modifications to existing homes, and commercial buildings. These requirements were originally for state-owned properties, but the code was changed to include privately-owned residential and commercial buildings.

According to the California Energy Commision (CEC), the state’s energy code was developed to “reduce wasteful and unnecessary energy consumption in newly constructed and existing buildings.” The energy codes establish a baseline, but building owners can exceed their requirements to achieve even greater energy savings.

Like most codes of its type, the 2019 California energy code covers the key aspects of building systems that determine energy consumption:

• Building envelope performance, including elements like insulation levels and windows.
• HVAC equipment, water heaters and other mechanical systems.
• Electrical installations, including lighting fixtures and lighting controls.

Title 24 calculations are normally among the last steps when planning and designing a building project in California. Since design decisions influence energy consumption, they also affect compliance. Ideally, the project scope and design specifications should be clearly defined before the Title 24 energy calculations. Otherwise, you must update the Title 24 forms with any major change, wasting time and skilled labor.

A completed Title 24 energy report validates that your proposed building design is compliant with the California Building Energy Efficiency Standards.

Every building project is unique, but normally you will need the following information for Title 24 energy calculations.

• A complete site plan that clearly shows the conditioned floor area. For projects in existing buildings, the site plan must clearly indicate new and existing areas.
• A detailed breakdown of the building floor area, by square footage and occupancy  type.
• The layout and specifications of all building envelope elements: windows, doors, insulations, roofing, skylights, etc.
• HVAC design
• Hot water system design
• Lighting design, including the luminaire layout and lighting schedule

As mentioned above, the Performance method provides more flexibility when designing these building systems. The Prescriptive method follows a simpler process with no need for energy modeling, but the Performance method can achieve the highest return on investment while meeting the code.

Some cities and counties in California have set the bar higher, requiring a building energy performance at least 15% above Title 24. Meeting this condition with the Performance method is simpler:

• Certified energy modeling software is used to compare the project with the baseline building.
• If the project is at least 15% more efficient, it gets approved.

Demonstrating a 15% higher efficiency with the Prescriptive method is very difficult, and not recommended by engineering professionals. In this case, it would be necessary to demonstrate a 15% higher performance for all the components used, consuming plenty of time and making the project more expensive than necessary. Consider that Title 24 uses standard formats for all cities and counties in California, even if local requirements vary.

When modifying an existing building, additional upgrades may be necessary to meet Title 24. Consider that energy performance requirements apply for the entire property, not only the modifications. Inefficient buildings may need several energy efficiency measures to reach the code performance level and get approval for a modification.

For commercial buildings in California, Title 24 energy calculations are are divided into three main performance areas: Building envelope compliance, mechanical compliance and lighting compliance

The energy performance of a commercial building is strongly determined by these three aspects. HVAC is normally the largest load in buildings, and its performance depends on both system specifications and the building envelope. Lighting systems are the second-largest load after HVAC in many cases. By focusing on these three areas, the Title 24 energy standards have improved commercial energy efficiency in California.

• Building envelope Title 24 calculations are necessary for any new commercial project. They also apply for any renovations that affect an existing envelope, and renovations that change the conditioned floor space in a building.
• Mechanical Title 24 calculations are required for new HVAC installations, and any additions or modifications to existing systems. Keep in mind that this includes equipment upgrades: even if you will install the most efficient HVAC units in the market, you must prove Title 24 compliance.
• Lighting Title 24 calculations are necessary for any new lighting installations or modifications to existing systems, and the project must meet the California Lighting Standards. Generally, you can achieve the highest possible efficiency by combining daylighting, LED fixtures and smart lighting controls.

Residential buildings with 4 or more habitable floors are considered high-rise under Title 24, and they must follow the commercial requirements of the California energy code. On the other hand, mixed-use buildings with less than 10% residential area must follow the commercial standards. However, a commercial building expansion that will be used only for residential purposes can be designed with the residential energy standards.