Agree, I think you can get some special glass / coatings that reflect the heat a bit but better not to have the sun hit the glass in the first place.Yea - insulation stops the transfer of heat, so it works both ways. But then we have big windows with solar glass that let in/amplify the heat as much as possiblehence the need for external shutters. Honestly, stopping of direct sunlight before it hits the windows would stop so much heat getting into more modern/well insulated houses.