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Austin TX Energy Code Changes Effective Oct 1,2010

  I recently attended a seminar at my Austin Home Builders Association regarding the changes to the International Energy Conservation Code.  We’re currently building under the 2006 IECC codes and the 2009 updates have been adopted by the City of Austin effective Oct 1, 2010.  Overall this new code will increase efficiency by about 15% compared to the 2006 code, but Austin has adopted some even stricter amendments to the 2009 codes so I’m guessing we’re closer to 17-18% for Austin homes built under this new code.
  (Keep in mind this article is based on building in Austin TX (zone 2) so if you’re reading this in Pennsylvania some of these will be different for your climate zone.)

  Here’s the Executive Summary of what I learned:

  • Window Glazing (glass) Solar Heat Gain Coeffecient goes from .4 down to .3
  • Window U-Factor Now: .65 NEW: .51 (Note: Aluminum Non-Thermally Broken windows will still meet code but need performance upgrades like Argon Gas and better spacers.  Likely low-end aluminum will not be seen anymore)
  • Manual J HVAC DESIGN is now a code requirement.  Installed Equipment must reasonably match Manual J
  • Envelope Testing   Code is 7ACH50 slightly more stringent than Austin’s current .5ACHnatural.  7ACH50 is close to .42ACHnatural.  
  • Wall Insulation Now R-13 meets code NEW: R-15 batts or R-13 Batts with R-2 exterior foam sheathing NOTE: Total Fill BIBS, Open Cell Spray Foam, & Blown Cellulose will all meet code
  • Attic Access required to meet insulation requirement of attic.  IE: R-30 attic needs R-30 on the attic door
  • Maintain attic insulation depth over conditioned space.
  • Unvented Attic- Must use air-impermeable foam.  Can be R21 if mechanical system is in the thermal envelope.  
  • High Efficacy Lighting 25% now NEW: 50% (lamps/bulbs) Austin Amendment takes this to 90%  (this is a BIG CHANGE)
  • Option of using a calculated lighting allowance of .6 watts/sqft to allow a mix of lighting.
Improved Hot Water Distribution Efficiency Austin Amendments (Not in the 2009 IECC)  

  • Automation and Insulation of Circulation Systems
  • Insulation of ¾” or larger hot water piping and runout serving kitchen sink
  • Restriction on Electric Resistance Water Heating – Can be used as secondary to solar    thermal or Heat Pump  Note: Ok to do electric water heating with De-super heat recovery system and with Geothermal systems. 
John Umphress from Austin Energy Green Building Program was the presenter of this code updates seminar and he gave the following tips for building under the new code.  

  1. Manual J is now required.  Including room airflows (Manual D)
  2. Use factory sealed air handlers
  3. Test your duct system at rough.  
  4. Install returns or pressure relief in all bedrooms.
  5. Make sure your return area is adequate (1sq foot per ton net)
  6. R21 Insulation when cooling is the point of diminishing return (IE Greater than R21 isn’t money well spent)
  7. R38 Insulation when heating is the point of diminishing return
Be sure to talk to your Architect or Builder about how these new codes will affect your construction project.  -Matt Risinger