Class 30 Window Minimum Efficiency Standard

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Class 30 Window Minimum Efficiency Standard
September 20, 2005 Revised September 19, 2006
2
Issue

• Current availability of class 30 windows
  restricts adoption of window efficiency
  improvement measure
• Program incentives for windows must produce
  incremental savings (i.e., do not simply pay for
  a measure that would have been installed without
  incentives)

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Background Why We Changed

• Original (1983) Council MCS called for adoption
  of Class 30 windows in PNW Energy Codes
• Current minimum efficiency standard for
  Residential Retrofit and New Construction
  programs is Energy Star (Class 35)
• Alliance program evaluation revealed that 80
  of windows sold in PNW are meet Energy Star
  (Class35)
• Energy Codes in Zone 2 (E. WA), Idaho and Montana
  require class 35 windows
• Class 30 window upgrades (over CL35) are
  cost-effective in all zones in both new and
  existing homes

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National Class 30 Window Availability
Source NFRC Data Base Extract by Craig Conner,
June 2005
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PNW Class 30 Product Availability
Source Phone survey of PNW manufacturers 09/06
by Gary Curtis, WestWall Group
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RTF Existing Recommendation

• RTF Recommends that commencing January 2006 or as
  soon as practicable thereafter, PNW residential
  weatherization and new construction programs
  adopt minimum efficiency standards for windows of
  class 30 (U-factor 30)
• ResWx specs now require class 30
• May be satisfied by achieving a area weighted
  average of class 30 (U-factor 30) or better

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Options

• Maintain current recommendation
• Accept lower penetration of window efficiency
  improvements until class 30 is more widely
  available
• Increase minimum U-factor
• This may not produce incremental savings over
  current Energy Star products, since many of these
  are U-0.34 to U-0.31 (Avg 0.33).
• No cost for this increment so what is
  justification for offering incentives
• Drop window efficiency improvement measure
• Only class 30 or better produce incremental
  savings and such windows are not widely
  available, eliminate as option until product
  availability improves