Sealed units in double glazing get misted up with condensation but they are easy to change. Follow the instructions on this video tutorial to be able to swap a double glazed glass sealed unit easily. The British Standard Kite Mark on the inside of your sealed unit should be BS EN 1279 which covers the production of insulated glass units. Further standards will also have been met but the company is not required to add these to the sealed unit providing the unit complys with the rest of the rules which is indicated by BS EN 1279. These further standards are

BS EN 1096 – covers coated glass (what about EN 673?)
BS EN 1863 – covers heat strengthened soda lime silicate glass
BS EN 12150 – covers thermally toughened soda lime silicate safety glass
BS EN 14449 – covers laminated glass and laminated safety glass
BS EN 1279 – covers insulating glass units. More information can be found here: https://www.diydoctor.org.uk/projects...