True, although with double glazing you can probably make the HVAC unit smaller, saving weight there too. And you might not need air vents to defog the screen e

True, although with double glazing you can probably make the HVAC unit smaller, saving weight there too. And you might not need air vents to defog the screen either - a well insulated window won't get condensation on it to start with. And double glazing typically needn't be much thicker than single glazing - as long as the air gap between the panels is sealed, then the air itself gives the whole window dynamic rigidity. That's why you sometimes see a thief throw a brick at a double glazed window and it doesn't break.