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California Poised to Issue 2013 Title 24 Building Efficiency Standards

May 16, 2012

The California Energy Commission is in the final stages of adopting changes to the 2008 Building Energy Efficiency Standards contained in the California Code of Regulations (CCR), Title 24, Part 6 (also known as the California Energy Code). The revised standards were approved May 9, 2012 and are scheduled to take effect in January 2014.

Ken Nittler, PE, (WESTLab) explained to AAMA Western Region  2012 Spring Meeting attendees that the upgraded standards are planned to go into effect in conjunction with the triennial upgrade of other parts of the California Building Standards Code and will be published as the 2013 California Energy Code. The updated standards will implement a number of state energy policy directives that have evolved since 2003, which Nittler characterizes as "very serious and ambitious goals and will require substantial improvements in efficiency."

Among these are:

  • GreenHouseGas (GHG) considerations, which identify buildings as second only to transportation in emissions. Legislation such as AB32 (2006, 2010) and executive orders (S-3-05, 2005) have established goals of reducing GHG emissions to 1990 levels by 2020 and to 80 percent of 1990 levels by 2050.
  • New building standards are to achieve "net zero energy" levels by 2020 for residences and by 2030 for commercial buildings.
  • The Green Building Standards Code calls for tiered energy performance levels of 15 percent and 30 percent more stringent than the 2008 mandatory standards. These goals are voluntary on a statewide basis, but local jurisdictions may adopt the Green Building Standards Code as mandatory at the local level.

Overview
The proposed 2013 standards focus on several key areas to improve the energy efficiency of newly constructed buildings (as well as additions and alterations to existing buildings), help reduce electricity demand reductions during critical peak periods and enable simple and efficient future solar system installations. This is expected to save California residents and businesses hundreds of millions of dollars in energy costs over the next decade, as well as benefit the environment.

Among the most significant efficiency improvements to the residential standards are those proposed for windows, the building envelope (wall, ceiling and floor) insulation and the testing of HVAC systems. Changes for all building types include:

  • Mandatory requirements for fenestration products (§110.6)
  • The threshold floor area, above which National Fenestration Rating Council (NFRC) ratings are required for field fabricated fenestration products, has been reduced.
  • Visual transmittance (VT) has been added to the fenestration product characteristics that must be tested and labeled according to NFRC procedures.

Non-Residential Prescriptive Standards
The following table summarizes the area-weighted new maximum (minimum for VT) fenestration performance criteria.
 

Non-Residential Prescriptive Fenestration Requirements - All Climate Zones
  Fixed Window Operable Window Curtain Wall/Storefront Glazed Doors
Maximum
U-factor
0.36 0.45 0.41 0.45
Maximum RSHG* 0.25 0.22 0.26 0.23
Minimum VT 0.42 0.22 0.46 0.17
Overall Max WWR (window-to-wall ratio)  40%

*
Relative Solar Heat Gain (RSHG)is the ratio of solar heat gain through a fenestration product (corrected for external shading) to the incident solar radiation. It is equal to the solar heat gain coefficient (SHGC) multiplied by a calculated correction factor based on the geometry and orientation of shading overhangs.

Actual project-specific prescriptive values vary within these maxima according to climate zone and type of operable window. Up to 10 square feet of fenestration area or 0.5 percent of the conditioned floor area, whichever is greater, is exempt from the U-factor requirement.

Other prescriptive requirements are 20 percent of floor area maximum glazing area and 5 percent of floor area maximum west-facing glazing.

Fenestration air leakage rate requirements, which apply to the entire building envelope, have been reduced to a maximum of 0.04 cfm/sf, which is consistent with air leakage requirements in the International Energy Conservation Code (IECC). An exception is added that exempts fenestration products from air leakage requirements if they are field fabricated.

The Component Modeling Approach (CMA) Alternative
Aside from the defined default values, the NFRC CMA can be used for commercial fenestration.*

Nittler noted during the presentation that part of the NFRC label certificate includes an “Actual Size” listing that is not for compliance and is not necessarily the actual configuration used on the job. The “actual size” is technically not certified by NFRC. The distinction between “standard size” and “actual size” ratings can be confusing, especially given that some buildings could have dozens of actual products, and will likely need to be clarified.

Daylighting
Mandatory requirements also include the use of daylighting sensors to adjust lighting systems near windows to produce more or less light based upon the amount of natural light entering the space. This includes (§140.3[c]) modified daylighting requirements for large enclosed spaces in low-rise buildings, with increases in the percent of floor area that must be daylit. A new subsection (§140.6[d]) describes a requirement for the installation of automatic daylight controls in secondary daylit zones (areas of the building located a horizontal distance from windows equal to twice the vertical distance between the floor and the top of the window.)

Changes for Low-Rise Residential Buildings
The 2013 standard has added a new subsection (§150.0[q]) that places a mandatory maximum conductive heat transfer (U-factor) requirement on all fenestration products separating conditioned space from unconditioned space. Revised prescriptive requirements for high-performance windows reduce the maximum U‐Factor to 0.32 and maximum SHGC to 0.25 in most climates (there are no SHGC requirements in mild coastal zones).

Authorized exceptions include installation of up to 12 sf of skylights with U-factor of 0.55 and SHGC of 0.30, and use of up to 3 sfof door glass and 3 sf of tubular daylighting device at any performance level.

"Component Packages" as defined in the 2008 version have been removed. The sole prescriptive package in the 2013 Standards (“Package A”) is what was called "Package D" in the 2008 Standards. As the basic prescriptive requirements for new residential construction, it is tuned to the 16 defined California climate zones. “Package E” for metal-framed windows, which allowed higher aluminum framed U-values by introducing tradeoffs with other features, has also been eliminated.

Additions and Alterations
Replacement windows must follow the residential prescriptive requirement. However, the new standards add an exception (§150.2[b]1.A) to the replacement fenestration requirements, such that if an alteration project has a limited amount of glazing area (less than 75 sf) with acceptable thermal and solar gain performance (U-factor up to 0.40 and SHGC up to 0.35), then the alteration project does not need to meet the replacement fenestration requirements.

Labeling Requirements
The 2013 California Building Energy Efficiency Standard requires every manufactured fenestration product to bear a clearly visible temporary label that lists the U-factor, the SHGC and VT and that certifies compliance with the air leakage requirements of Section 110.6(a)1.

Products rated through the CMA and site-built fenestration products must have an associated label certificate that lists the U-factor, SHGC and VT.

For more details on the status of the 2013 California Building Efficiency Standards, visit the California Energy Commission website.

*NFRC’s CMA certification process is outlined in
The CMA Certification Process in California, appearing the Western Region Spring 2011 e-News.

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