Double glazing is a window with two panes of glass and a vacuum between the glass. The vacuum reduces the rate of energy transfer by convection. This keeps the cold air out and the warm air in, a dry air layer reduces the chance of energy transfer by conduction.
An aluminium layer prevents the rate of energy transfer and therefore keeps the house warmer. It reflects the radiation away from the wall.
Loft insulation like fibreglass, reduces energy transfer through the roof. The air between the fibre reduce the rate of energy transfer by conduction.