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Measure Description

A summary of the proposed code changes for advanced daylighting design is provided below.

Proposal A: Power Adjustment Factors

The proposed measure will allow Power Adjustment Factors (PAFs)* and performance compliance options (PCOs) for indoor lighting that are controlled by daylighting controls when certain technologies are installed in the proposed building. The PAFs and PCOs may be applied to any nonresidential building subject to the provisions of Title 24, Part 6.

The proposed technologies include: fixed slats (louvers), light shelves, clerestories, and daylight redirecting devices. These technologies tend to increase the daylight potential (area or number of hours) of a space.

Previously, no credit could be taken for certain innovative technologies that increase the daylight potential of a space. Offering PAFs and PCOs for these encourages their use. It is possible that the introduction of these technologies into the 2019 update may provide a gradual path to their prescriptive requirement in future updates.

The Statewide CASE Team completed a detailed analysis to determine the appropriate PAFs for all daylighting devices. This report documents the methodology and assumptions used in the analysis. Electric lighting energy impacts were included in the savings analysis but heating, ventilation and air-conditioning energy impacts were not.

Proposal B: Min VT Interpretation for TDDs

An interpretation of the Minimum Visible Transmittance (Min VT) requirement for plastic skylights (Table 140.3-C) is proposed for Tubular Daylighting Devices (TDDs). This is based on a new National Fenestration Rating Council (NFRC) Test Procedure (NFRC 203) for TDDs.

Proposal C: Update to Daylit Zones Definitions

An update to the Skylit Daylit Zone definition is proposed to ensure proper interpretation for skylights in atriums, and to the Sidelit Daylit Zones definition for building with large exterior overhangs.

*Power Adjustment Factors are multipliers on the proposed design’s lighting power. From a compliance perspective they effectively reduce the proposed design’s lighting power. As such, a higher lighting power may be reduced enough to meet the maximum allowed lighting power of Title 24, Part 6.


The Statewide CASE Team 2019 Title 24, Part 6 Final CASE Report is available below. The Final CASE Report incorporates feedback received during utility-sponsored stakeholder meetings, Energy Commission Pre-Rulemaking workshops, and personal communication with stakeholders.

Presentations and Meetings

  1. Presentation from Stakeholder Meeting on December 15, 2016
  2. Notes from Stakeholder Meeting on December 15, 2016
  3. Presentation from Stakeholder Meeting on March 30, 2017
  4. Notes from Stakeholder Meeting on March 30, 2017

Code Language

  1. Draft Code Language


  1. Needs Assessment Report
  2. CASE Study Results Report
  3. Final CASE Report
  4. Draft CASE Report

Give Us Your Feedback

The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.

  • Use the form above to provide feedback on this measure.