Conservatory assessments are carried out in the same way as assessments for extensions. These SAP Assessments can be undertaken on existing older conservatories where the homeowner would like to remove the wall or doors between the existing house and the conservatory, or where there is a new conservatory proposed without thermal separation from the house.
Approved Document L1B states that any extension can have an allowable glazing amount of 25% of the new floor area, plus the area of any openings being covered by the extension (i.e. the existing windows in the wall between the house and the extension). However, if you are planning a conservatory with, you can still show compliance by using SAP to show that your carbon emissions are no worse than if you had a normal extension with the correct amount of glazing.
SAPs UK carry out many of these types of assessment every year, and always find a solution to achieve compliance.