A draught lobby is an arrangement of two doors forming an enclosed space on the main entrance to the dwelling. To be specified as a draught lobby in a house in DEAP, the enclosed space must satisfy all the following criteria:
An unheated draught lobby in the form of an external or thermally separated porch should not be counted as part of the floor area of the dwelling as described in the porches section on the dimensions tab, although it may still be counted as a draught lobby in the ventilation section. However, the door between the dwelling and the porch is an element adjacent to an unheated space and its U-value should be calculated accordingly (see here).
Apartments with access via an enclosed stairwell or corridor should be classified as having a draught lobby.
The ’draught lobby‘ entry in DEAP does not have a bearing on whether the lobby is included in the dwelling floor area or not. Guidance on determining whether the lobby is included in dwelling floor area is set out in the dimensions section here as applied to the DEAP building: floors tab.