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Steel Framing For The California Residential New Construction Market: Title 24 Energy Standards

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

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Steel Framing For The California Residential New Construction Market: Title 24 Energy Standards

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

  2. 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

  3. ConSol’s 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

  4. 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?

  5. Thermal Efficiency of Framing • Heat Transfer: • R-value (resistance to heat transfer) • U-factor’s (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)

  6. 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

  7. 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

  8. 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

  9. 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?

  10. Steel Wall Efficiencies

  11. Steel Attic Efficiencies

  12. 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

  13. 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

  14. CA 2005 Standards - continued • Efficiency of framing derived from Joint Appendix Section IV

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

  16. 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

  17. 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

  18. 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)

  19. 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

  20. Market Barrier: Education • Steel has benefits • Not parlayed to market • Homebuyers • If it’s not visible… • Builders • Don’t understand all the benefits • Assume stick for stick replacement to wood • Concerned about first costs

  21. 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

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

  23. 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

  24. 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

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

  26. 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

  27. Utility Rebate Programs • Rebates for meeting Energy Star • Benefits: Brand recognition + rebate • Drawbacks: Rebate doesn’t offset cost of Steel • Also cost of Thermal Bypass Checklist

  28. 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

  29. 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

  30. 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...

  31. Thank You!Questions? Rob Hammon, Ph.D. Principal, ConSol (209) 473-5000 7407 Tam O’Shanter Stockton, CA 95210

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