Low-E Storm Window Information

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 Cost	Annual Energy Savings	Simple Payback (yrs)
House 1: Low-E	$1,738	$490	3.5
House 2: Clear	$1,344	$111	12.1
House 3: Clear	$2,661	$317	8.4
House 4: Low-E	$1,738	$341	5.1

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