During a survey to produce an energy performance certificate Northern Ireland recently I came across a flat where the lowest occupied floor area is entirely located within what would be classed as a “room in the roof”. The flat does not have an area located at a lower level. 

The explanation below identifies the correct way to record the flat in order to produce an accurate epc in Northern Ireland. In the current version of RdSAP it is not possible to have a property that has dimensions only entered in the roof room value field.  Therefore to enable the correct reporting of this type of property it will need to be treated as a flat, with an average height of 2.2m. 

The domestic energy assessor will need to specify the main wall area approximately (typically timber frame).  Noting any alternative wall where appropriate, this will consist predominately of the gable ends of the roof space but could also include the common wall if total areas exceeded the10% alternative wall rule. The potential for entering an alternative wall could be used to better represent the thermal properties of a flat. 

The DEA would need to calculate the area of alternative wall to decide if it was greater than the 10% rule used within RdSAP. The remaining details for the property would then be added as normal