Steel Framing For The California Residential New Construction Market: Title 24 Energy Standards Robert Hammon, Ph.D. Principal

ConSol 25 years providing energy solutions to production builders Title 24 Updates: CBIA Technical Support T24 Calcs for About 15% of Permits in CA Mechanical Design ComfortWise ® Consulting

ConSols Consulting Dept US Department of Energy –Building America –Zero Energy Homes California Energy Commission –Zero Energy New Homes –Energy Code Training Utilities –Residential New Construction Program Support –Zero Energy New Homes –Energy Code Training –Community Energy Efficiency Program Manufacturers and Associations

Steel Framing and Energy Efficiency: Background What makes framing important to energy? –Heat transfer CA Energy Efficiency Standards (T24) –How deals with walls and ceilings What is typical wall construction? How is a typical steel wall different?

Thermal Efficiency of Framing Heat Transfer: –R-value (resistance to heat transfer) –U-factors (heat transfer rate) –Thermal break/ thermal bridging (% knockout) –Percent of framing in wall cavity –Emissivity of exterior surface –Reflectance of exterior surface –Infiltration (uncontrolled airflow)

Title 24 (2005 Standards) Mandatory Minimum Measures –R-13 wall –R-19 ceiling Prescriptive Packages –Insulation, windows, equipment efficiencies –16 Climate Zones Performance Approach –Less or equal energy as Prescriptive –Mandatory minimums apply Updated triennially

Typical Wall Construction Equivalent to 2005 Standards mandatory min –Material: Wood –Dimensions: 2 x 4 studs –Spacing: 16 o.c. –Percent framing: 24% –Cavity Insulation: R-13 Batt –Sheathing Insulation: None –Overall Performance: u-factor = 0.102

Typical Steel Framing C-studs w/ foam sheathing –Min R-5 sheathing to satisfy code mandate –Foam installed internal or external or both Similar construction technique as wood –16 oc is 24 percent framing factor Overall performance: u-factor = 0.102

Common Questions Q1: What is the affect of increasing the spacing from 16 to 24 o.c.? Q2: How effective is foam sheathing? Q3: What if I am using a blown-in insulation rather than fiberglass batts? Q4: How energy efficient is a steel wall in comparison to a wood wall? Q5: What is the impact of different types of foam sheathing?

Steel Wall Efficiencies

Steel Attic Efficiencies

CA 2005 Standards 15 percent more efficient than 2001 Standards (Statewide) Significant, fundamental changes in code –Energy vs. TOU (TDV) Energy Peak energy is valued higher than off-peak Measures that reduce peak are more valuable Wall efficiencies are more important under TDV

CA 2005 Standards - continued Cavity insulation installation quality assumed poor –Penalized unless HERS inspector can verify quality –Credit for quality installation not available to steel Framing factors change from 16% to 24% –Based on study of wood framed homes –Foam sheathing becomes more important

CA 2005 Standards - continued Efficiency of framing derived from Joint Appendix Section IV Wall Efficiencies CavityEFSWood U-factorSteel U-factor

Market Demands Meet code –CA 2005 Standards (Title 24) Low cost Low liability Contractor availability –Contractor driven market

Market Demand: CA Code Mandatory measures –Min efficiency of 2x4 wall with R-13 cavity Prescriptive packages –Wood framed walls with up to R-21 cavity Performance method –Evaluate overall building performance –Certain efficiency measures can be offset against each other

Market Demand: Low Cost Labor and materials (L&M) Energy design cost (EDC) –External foam sheathing –Additional energy design measures necessary to comply with performance L&M + EDC = Total installed cost (TC) TC of traditional steel framing > TC of traditional wood framing

Market Barriers Builders resistant to change Building industry has a minimal understanding of steel CA minimum wall efficiency requires foam for steel framed walls Builder apprehension to foam sheathing (one- coat stucco systems)

Market Barrier: Current Practice CA only 8% steel framing (AISI 02) Designs are typically a stick for stick replacement of wood Exterior foam sheathing is necessary to meet mandatory measures

Market Barrier: Education Steel has benefits Not parlayed to market Homebuyers –If its not visible… Builders –Dont understand all the benefits –Assume stick for stick replacement to wood –Concerned about first costs

Market Barrier: Code 2005 Standards –Removed method for using alternative assemblies (FORM 3R) –Efficiency of framing derived from Joint Appendix Thermal resistance of steel much less than wood –R-19 wood framed attic ~ R-30 steel framed attic Steel typically requires external foam sheathing

Solutions Advanced framing techniques Additional exterior foam sheathing Propose changes in the 2008 Standards Convey message about benefits Align with energy efficiency programs

Solution: Advanced Framing 19.2 or 24 o.c. Reduce Cost –Lower labor and material cost Increase Efficiency –Maximize the cavity insulation –Reduce the thermal bridging Knockout 2x6 Lower conductance wall and exterior treatments

Solution: Foam Sheathing Sheathing is better than cavity insulation –Reduces the thermal bridging affect Typically R-3.8 per inch Increase the thickness –Probably the most effective of the solutions Improve the sheathing R-value –R-5 per inch is available

Solution: Messaging 2006 California Energy Star Utility rebate programs Federal tax credits

California Energy Star 2006 Energy Star Requirements 15 percent better than CA standards Thermal-bypass checklist (TBC) –Indoor Air Quality –Insulation installation quality Benefit: Brand recognition Drawback: Expensive to meet the TBC

Utility Rebate Programs Rebates for meeting Energy Star Benefits: Brand recognition + rebate Drawbacks: Rebate doesnt offset cost of Steel –Also cost of Thermal Bypass Checklist

Federal Tax Credits 50% better than 2004 International Energy Efficiency Standards (IECC) Significantly built on or after Oct 1, 2005 Transferred to owner on or after Jan 1, 2006 through Dec 31, 2007 Required, third party inspector Benefits: $2000 credit per qualified home –Assist with additional costs

Solution: 2008 Standards AISI and SFA actively monitoring 2008 Monitor proposals for fairness and accuracy –Attic model –Ventilation for IAQ Potential proposals –Adjust framing factor for 16 oc, 19.2 oc and 24 oc May require research and documentation –Credit for quality installation of insulation in steel framing May require research and documentation

Summary 2005 Standards have significantly affected the entire industry Sheathing is a cornerstone in all cost efficient solutions Improve messaging AISI and SFA are working for you...

Thank You! Questions? Rob Hammon, Ph.D. Principal, ConSol (209) Tam OShanter Stockton, CA 95210