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

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

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-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)

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

Table IV.11 – U-factors of Metal Framed WallsCavity Rated R-value of Continuous InsulationInsulation Nominal R-0 R-2 R-4 R-6 R-7 R-8

Spacing R-Value: Framing A B C D E F 16 in. OC None Any 1 0.458 0.239 0.162 0.122 0.109 0.098

R-11 2x4 2 0.224 0.155 0.118 0.096 0.087 0.080 R-13 2x4 3 0.217 0.151 0.116 0.094 0.086 0.079 R-15 2x4 4 0.211 0.148 0.114 0.093 0.085 0.078 R-191 2x6 5 0.183 0.134 0.106 0.087 0.080 0.074 R-21 2x6 6 0.178 0.131 0.104 0.086 0.079 0.073 Foamed Plastic 2 x 4 14 0.218 0.152 0.116 0.094 0.086 0.079 or Cellulose 2 x 6 15 0.179 0.132 0.104 0.086 0.079 0.074 Insulation 2 x 8 16 0.157 0.119 0.096 0.081 0.075 0.070

24 in. OC None Any 24 0.455 0.238 0.161 0.122 0.109 0.098 R-11 2x4 25 0.210 0.148 0.114 0.093 0.085 0.078 R-13 2x4 26 0.203 0.144 0.112 0.092 0.084 0.077 R-15 2x4 27 0.197 0.141 0.110 0.090 0.083 0.076 R-191 2x6 28 0.164 0.123 0.099 0.083 0.076 0.071 R-21 2x6 29 0.161 0.122 0.098 0.082 0.076 0.070

Steel Attic Efficiencies

Table IV.4 – U-factors of Metal Framed Attic Roofs

Nominal Cavity Rated R-value of Continuous Insulation Framing Insulation R-0 R-2 R-4 R-6

Spacing Size R- Value: A B C D 16 in. OC 2x4 R-19 4 0.073 0.064 0.056 0.051

R-22 5 0.060 0.054 0.049 0.044 R-25 6 0.052 0.047 0.043 0.039 R-30 7 0.042 0.038 0.036 0.033 R-38 8 0.032 0.030 0.028 0.027 R-49 9 0.024 0.023 0.022 0.021

24 in. 2x4 R-19 14 0.065 0.057 0.051 0.047 R-22 15 0.055 0.049 0.045 0.041 R-25 16 0.047 0.043 0.040 0.037 R-30 17 0.039 0.036 0.034 0.031 R-38 18 0.030 0.028 0.027 0.025 R-49 19 0.023 0.022 0.021 0.020

* Continuous insulation shall be located at the ceiling or at the roof and be uninterrupted by framing.

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

Cavity EFS Wood U-factor Steel U-factor

13 0 0.102 0.217

13 4 0.068 0.116

13 8 0.052 0.079

21 0 0.069 0.178

21 4 0.051 0.104

21 8 0.041 0.073

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 it’s not visible…

• Builders – Don’t 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 doesn’t 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) 473-5000

7407 Tam O’ShanterStockton, CA 95210