ESP = Energy Saver Package double pane version of the Enviro-Star 800 Series sliding window is a serious option to consider. It has a heavy duty foam filled frame for maintenance free durability and beauty. We make it easy with our no hassle sales approach. Let Wonder Windows educate you on the difference between our windows and any other manufacture.

  • 7% Better U-Value than Energy Star┬« minimum
  • 600% Better Air Infiltration protection
  • Wide selection of hardware options
  • Superior craftsmanship
  • Full integral interlock with double weather-stripping.
  • Full 3┬╝" Depth Welded Mainframe
  • Beveled colonial exterior features
  • Available in standard and custom exterior colors
  • Maintenance free, for years of long lasting performance.
  • Heatseal┬« warm edge spacer system for excellent thermal efficiency and drastic reduction in the possibility of condensation on the inside of the window.
  • Available in Replacement and New Construction applications.
          Energy Star Comparison To
Glazing Option U-Value SHGC VT CR Minimum* Energy Star Minimum
Dual Glazed              
With ESP 0.28 0.28 0.52 63 0.30    7% Better


      Industry Comparison To  
  Our Windows Minimum Industry Minimum  
AAMA Rating R 50 R 15      
Air Infiltration cfm/ft2 0.05 0.3  600% Better
Water Penetration mph   62 33  88% Better  
Structural Integrity mph 171 94  82% Better