what are the differents between single/double plane window

The double plane window can reduce heat gain by condution because the air between

the double plane window is a good insulator. Therefore, the double plane window can

gain to make the room temperature lower.

the single plane window doesn't have any air between it. Therefore, it can't reduce heat

gain by surrounding.

Double-pane windows of a building can reduce the heat loss to the surroundings. This is especially useful during nights or winters. This is because there is an air layer, which is a poor heat conductor, between the window panes.

However, during daytime, the heat transferred to the building through windows are mainly by radiation but not conduction. Double-pane windows can reduce just a bit more radiation than single-pane windows. So, Double-pane windows are not so effective in reducing heat gain in daytime.

However, in Hong Kong, where winter is not too cold or long, double-pane windows are mainly used to reduce noise from surroundings. I used to live in a building who was close to the old Kai Tak Airport runway. The double-pane window proved to be very effective in reduing the noise of the airplanes.

--
Notes:
All are my own words.
It should be "window pane" not "window plane".