Low-E Storm Window Information

Installed window

Features:

  • Pyrolytic Low-E coating (hard coat)
  • Does not degrade in non-sealed cavity
  • Identical installation cost to clear storms
  • Greatly reduced air leakage

Savings

Whole house heating energy savings over a winter season in Chicago for new storms:

  • Clear storm windows 8-18%
  • Low-E storm windows 19-27%

Estimated U-values:

  • Clear storm windows: 0.49 Btu/h-ft2-F
  • Low-E storm windows: 0.36 Btu/h-ft2-F

Cost Effectiveness

 Total Window CostAnnual Energy SavingsSimple Payback (yrs)
House 1:
Low-E
$1,738$4903.5
House 2:
Clear
$1,344$11112.1
House 3:
Clear
$2,661$3178.4
House 4:
Low-E
$1,738$3415.1

Technical Data

Key performance indices:

U-factor

  • Thermal resistance
  • Units Btu/hr-ft2-F
  • R-Value is inverse, U=0.2, R=1/0.2 = 5 hr-ft2-F/Btu

SHGC

  • Solar Heat Gains
  • Ranges from 0-1, higher means more solar gains

VT

  • Visible Transmittance
  • Ranges from 0-1, higher means more daylight

Technical Studies and References

About The Alliance for Low-E Learn about Low-E Windows Resources