California Title
24 Building Energy Standards
Why
California needs Energy Efficiency
Standards
Because
energy efficiency reduces energy costs, increases reliability and availability
of electricity, improves building occupant comfort, and reduces impacts to the
environment, standards are important and necessary for California’s energy
future.
Energy Savings
Reducing energy use is a
benefit to all. Homeowners save money, Californians have a more secure and
healthy economy, the environment is less negatively impacted, and our electrical
system can operate in a more stable state. The 2005 Standards (for residential
and nonresidential buildings) are expected to reduce the growth in electricity
use by 478 gigawatt-hours per year (GWh/yr) and reduce the growth in gas use by
8.8 million therms per year (therms/yr). The savings attributable to new
low-rise residences are 99 GWh/yr of electricity savings and 5.5 million therms.
Additional savings result from the application of the Standards on building
alterations. In particular, requirements for fenestration replacement and duct
sealing in existing buildings are expected to save about 41 GWh/yr of
electricity and 3.0 million therms/yr of gas. These savings are cumulative
resulting in six times the annual saving over the three years to the next
standard cycle.
Electricity Reliability and
Demand
Buildings are one of the major
contributors to electricity demand. We learned during the 2000/2001 California
energy crisis, and the East Coast blackout in the summer of 2003, that our
electric distribution network is fragile and system overloads caused by
excessive demand from buildings can create unstable conditions. Resulting
blackouts can seriously disrupt business and cost the economy billions of
dollars. Since the California electricity crisis, the Energy Commission has
placed more and more emphasis on demand reductions. Changes in 2001 (following
the electricity crisis) reduced electricity demand by about 150 megawatts (MW)
each year. The 2005 Standards are expected to reduce electric demand by another
180 MW each year. Like energy savings, demand savings accumulate each year.
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.
Introduction to the Residential Standards
This section introduces the basic concepts and approaches for
complying with the lowrise 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. 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.
• Performance
Method ("Alternative
Calculation Method"). The use
of Energy Commission-approved
computer
methods provides the most
flexibility and accuracy in calculating energy use. Detailed accounting
of energy trade-offs between
measures is possible with this approach. 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.
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.
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.
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:
