On Tue, 12 Jul 2011 11:29:06 -0700 (PDT), kansascats
wrote:

is aluminum foil adhered to inside of double pane window ok? or
might that overheat the air gap between panes?

Dual pane glass are sealed units. Often filled with argon gas. You
cannot put anything "inside".

Film can break the glass and void the warranty (mentioned)

See Q4 on this page.

http://www.iwfa.com/ConsumerInfo/FAQs.aspx