There are no insulation requirements for the opaque parts of a door or door set if you are following the schedule method in Acceptable Solution H1/AS1.
The exemption of opaque doors from insulation requirements has been included to ensure that the schedule method is easy to apply and not too restrictive.
However, the door exemption is not intended to allow large areas of a house to be un-insulated; nor does it indicate that doors are typically well insulated.
If the calculation method is used, the total area of doors that exceed 3m2 must be treated as a wall.
You must consider glazing in doors when calculating the glazing ratio as it is part of the total area.