Aluminium windows are generally sealed and airtight glass panes which are stored separated by a spacer bar in amongst. The sealing is used only close to the edges leaving an air gap in between. This air gap makes these form of windows extremely electricity productive as the heat conduction is vastly reduced. The gain of this is that throughout winter, there is more heat within the home and during the summertime months, a lot more heat will get transferred exterior keeping the residence cool and at ease. #links# My websites: Good quality and Performance of Aluminium Patio Doors and Space Dividers With Slim Frames and Lower Sills