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2019 Cycle

High Performance Attics

Multifamily
Single Family
Envelope

Measure Description

The proposed residential high performance attic (HPA) measure increases the prescriptive performance of the residential envelope in certain climates, primarily reducing the cooling season heat transfer through the roof deck, contributing to lower heating, ventilation, and air conditioning (HVAC) loads. The HPA measure as represented in Title 24, Part 6 is based on a traditional ventilated attic with insulation at the ceiling and either ducts fully located in conditioned space or additional insulation added above or below the roof deck. This proposed prescriptive measure only applies to single family and low-rise multifamily buildings in new construction. No changes to the current 2016 HPA prescriptive requirements are being proposed for additions.

In regards to the assumed Standard Design reference case (tile roof with air space between the roof deck and the roofing material) in the performance method, the proposed measure increases the below-deck insulation R-value to:

  • R-19 in Climate Zones 4, and 8 through 16 for single family homes, and
  • R-19 in Climate Zones 4, 8, 9, and 11 through 15 for low-rise multifamily buildings.

This specification represents the proposed prescriptive requirement for the predominant tile roof configuration seen in California production housing. Equivalent performing cases for roofing systems without an air space (typically the case for asphalt roofing materials) and above deck insulation options were also developed and are reported in Section 7.1. Using the performance path, a builder has the full flexibility to choose to follow the prescriptive path, including the proposed 2019 HPA requirements, or trading HPA off against other efficiency measures.

Resources

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 September 14, 2016
  2. Notes from Stakeholder Meeting on September 14, 2016
  3. Presentation from Stakeholder Meeting on March14, 2017
  4. Notes from Stakeholder Meeting on March 14, 2017

Code Language

  1. Draft Code Language – March 2017

Reports

  1. CASE Study Results Report
  2. Final CASE Report
  3. 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.