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California Title 24 Building Energy Standards   

California's Energy Efficiency Standards for Residential and Nonresidential Buildings

The Energy Efficiency Standards for Residential and Nonresidential Buildings were established in 1978 in response to a legislative mandate to reduce California's energy consumption. The standards are updated periodically to allow consideration and possible incorporation of new energy efficiency technologies and methods. New standards were adopted by the Commission in 2001 as mandated by Assembly Bill 970 to reduce California's electricity demand. The new standards went into effect on June 1, 2001. The standards (along with standards for energy efficient appliances) have saved more than $20 billion in electricity and natural gas costs. It is estimated the standards will save $57 billion by 2011.

Legal Requirements – The Warren Alquist Act

Section 25402 of the Public Resources Code directs the California Energy Commission to:

"Prescribe, by regulation. . . building design and construction standards which increase the efficiency in the use of energy for new residential and new nonresidential buildings.

Changes to the Standards occur periodically to account for improvements in conservation technologies, changes in the cost of fuels and energy-conserving strategies, and improved capabilities in analyzing building energy performance. In addition, modifications are also made to further improve compliance and enforcement.

Benefits of Energy Conservation

This section discusses some of the underlying reasons why Standards are important and necessary for California’s energy future.

Comfort
Comfort is an important benefit of energy efficient houses. Energy efficient houses are well insulated, less drafty and use high performance windows and/or shading to reduce solar gains and heat loss. Poorly designed building envelopes result in houses that are less comfortable. Often comfort cannot be achieved in poorly designed houses, even with oversized heating and cooling systems.

Economics
For the homeowner, investing in building energy conservation helps to ensure that energy use in residences is affordable both now and into the future. Banks and other financial institutions recognize the impact of efficiency through energy efficient mortgages. From a larger perspective, the less California depends on depleatable resources such as natural gas, coal and oil, the stronger and more stable the economy will remain in the face of energy cost increases. A Cost-effective investment in energy efficiency helps everyone.

Environment
In many parts of the world, the use of energy has led to oil spills, acid rain, smog and other forms of environmental pollution that have ruined the beauty people sought to enjoy. California is not immune to these problems, but the risks would be greater without appliance standards, building standards and utility programs that promote efficiency and conservation. Other benefits are reduced destruction of natural habitats, which in turn helps protect animals, plants and the natural systems.

Global Warming
Burning fossil fuel is a major contributor to global warming, as carbon dioxide is added to an atmosphere already containing 25% more than it did two centuries ago. Carbon dioxide and other gasses add an insulating layer to the earth that leads to global climate change. California Energy Commission research shows that most of the sectors of the state economy face significant risk from climate change including water resources (from reduced snow pack), agriculture, forests and the natural habitats of a number of indigenous plants and animals.

Most scientists recommend that actions be taken to reduce emissions of carbon dioxide and other greenhouse gasses. While adding scrubbers to power plants and catalytic converters to cars is a step in the right direction, those actions do not limit the carbon dioxide we emit into the atmosphere. Using energy efficiently is a far-reaching strategy that can make an important contribution to the reduction of greenhouse gasses. The National Academy of Sciences urged the whole country to follow California's lead on such efforts, saying that we should make conservation and efficiency the chief element in energy policy. Their first efficiency recommendation was simple: Adopt nationwide energy efficient building codes. Energy conservation will not only increase comfort levels and save homeowners money; it will also play a vital role in creating and maintaining a healthy environment.

Introduction to the Residential Standards

This section introduces the basic concepts and approaches for complying with the low rise residential standards. There are two methods for complying with the residential energy Standards:

• Prescriptive Packages ("Alternative Component Packages"). The simplest approach in which each individual component of the proposed building must meet a prescribed minimum energy requirement.

• Performance Methods ("Alternative Calculation Methods"). Computer performance methods provide the most flexibility and accuracy in calculating energy use. Detailed accounting of energy trade-offs between measures is possible with the computer programs.

With either of these compliance paths, there are mandatory measures that still must be installed. Where superseded by a more stringent requirement to achieve compliance with the energy budget or prescriptive package, the more stringent feature becomes mandatory.

Note: The following buildings types are exempt from the prescriptive and performance standards.

(a) Seasonally occupied agricultural housing limited by state or federal agency contract to occupancy not more than 180 days in any calendar year.
(b) Low-rise residential buildings that use no energy obtained from a depletable source for either lighting or water heating and obtain heat from wood heating or other non-mechanical system.

Mandatory Measures

The mandatory measures require minimum ceiling, wall, and raised floor insulation; minimum HVAC (heating, ventilating and air conditioning) and water heating equipment efficiencies, and other requirements. The mandatory measures are required features with either the prescriptive or performance standards. For example a building may only need R-7 floor insulation to meet the performance standards, but R-19 must be installed because that is the mandatory minimum.

Prescriptive Packages

The prescriptive approach is the least flexible yet simplest compliance path. It is simple because an applicant need only show that a building meets each minimum or maximum level prescribed in the set of requirements contained in a package; few calculations, if any, are needed to demonstrate compliance. However, both packages C and D require diagnostic testing of air distribution ducts, split system air conditioners and split system heat pumps.

Note: The Alternative to Package D allows use of higher performance fenestration, and sometimes, higher efficiency HVAC equipment in lieu of duct testing and installing TXV's.

Two prescriptive packages are designated for each climate zone by the letters C or D. Within any given package, every single feature must be met in order for the building to comply. Package D requirements form the basis of trade-offs using the performance method. There is also an Alternative to Package D that substitutes high efficiency equipment and high performance glazing (depending on climate zone) instead of duct sealing, TXV's or refrigerant charge and airflow measurement.

Package C has higher insulation levels, but permits electric resistance heat. Package C may only be used in areas where natural gas is not available."

The following compliance documentation showing that the building complies is required to be submitted with the prescriptive approach.

• CF-1R Certificate of Compliance (required)
• MF-1R Mandatory Measures Checklist (required)
• Form 3R Construction Assembly U-factor (if applicable)
• Form 3RM Masonry Wall Assembly (if applicable)
• Form CF-4R Field Verification and Diagnostic Testing (if applicable). This form is usually required when Package D or Package C is used since the package requires diagnostic testing of air distribution ducts, split system air conditioners and heat pumps.
• Form S Solar Heat Gain Coefficient Worksheet (if applicable)
• DHW-1 Water Heating Calculations (if applicable)

Two additional forms, the Installation Certificate (CF-6R) and the Insulation Certificate (IC-1) are required during construction and must be posted or made available to the enforcement agency during building inspection.

Performance Methods

The use of Energy Commission-approved computer methods represents the most detailed and sophisticated method of compliance. While this approach requires the most effort, it also provides the greatest flexibility. The computer program automatically calculates the energy budget for space conditioning. The budget is determined from the standard design, a version of the building, which is upgraded or downgraded to achieve minimum compliance with the prescriptive Package D conservation features. 

The energy budget for space conditioning is expressed in thousands of Btu (kBtu) per square foot per year. The program also calculates the budget for water heating energy use in kBtu per dwelling unit. The water-heating budget is translated into a kBtu per square foot per year value and added to the space-conditioning budget to yield the combined energy budget. To comply with the Standards, the predicted combined "Energy Use" of the Proposed Design cannot exceed the combined "Energy Budget" of the Standard Design.

The following compliance documentation showing that the building complies is required to be submitted with the performance approach.

• CF-1R, Certificate of Compliance (required)
• MF-1R, Mandatory Measures Checklist (required)
• CF-2R, Computer Method Summary (required)
• Form 3R, Construction Assembly U-factor (if applicable)

The Installation Certificate (CF-6R) and Insulation Certificate (IC-1) are required during construction. If features are used for compliance that require field verification and diagnostic testing a CF-4R is required at the completion of construction.

California Climate Zones

Energy use depends partly on climate conditions, which differ throughout the state.  To standardize calculations and to provide a basis for presenting the criteria, the Energy Commission has established 16 climate zones, which are used with both the low-rise residential and the nonresidential standards. See the figure below.

Note: Cities may occasionally straddle two climate zones. In such cases, the exact building location and correct climate zone should be verified before any calculations are performed. If a single building development is split by a climate zone boundary line, it must be designed to the requirements of the climate zone in which 50% or more of the dwelling units are contained.

California Climate Zones 1-16:

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Last modified: 01/12/09