The most common types of fully glazed doors, with a glazed area of 60% or more - French, folding and
sliding – are included in the scheme and are rated on the scale ‘A’ to ‘G’, though most product will achieve a ‘C’ rating or above. The higher bands for these glazed products better reflect the inclusion of solar gain into the DER calculation as required by the Standard Assessment Procedure (SAP) 2009.

In fact, the DER for glazed doors follows exactly the rating formula that currently pertains to BFRC Window Energy Ratings.