Tandem Windows for High Energy Efficiency

A tandem window assembly for installation in a window opening in a wall, having an interior portion and an exterior portion and a thickness therebetween, comprising:

• an inner primary window assembly and a separate outer primary window assembly each installed independently of one another on respective interior and exterior portions of said window opening in said wall, said window assemblies, when installed in said window opening, defining an interstitial space between said respective separate window assemblies and surrounded by said window opening in said wall, said interstitial space being of a predetermined depth set by an installer to enable separate operation of said respective windows.

A method of installing tandem windows in a window opening in a wall to improve the energy efficiency of the window installation, comprising the steps of:

• installing a first primary outer window assembly to an outer portion of said window opening,
• selecting a desired separation for installation of a second primary inner window and, thereafter, installing a second separate primary inner window assembly to a second interior portion of said window opening,
• thereby defining, between said installed windows, an interstitial space of said desired separation that is surrounded by the frames of said primary widows and by said window opening, said interstitial space enabling separate operation of said respective window assemblies, providing access for cleaning, and for other purposes.