D Profile:

Advantages of Draught Proofing - As a rough guide, fitting draught proofing can reduce your heating bill by £8-10/year per window or door.

Your house or commercial property will lose heat during cold weather partly due to poor thermal insulation, but also due to air infiltration or the permeability of the building. Infiltration or permeability is measured in metres cubed per hour per square metre of floor area.  
 
A typical building built 1900 to 1990 will loose around 15-25 meter cubed of air per hour per square meter of floor area.  
 
This is due to natural leakage through the fabric of the building, but largely through gaps around windows and doors. Good use of draft proofing could reduce your air permeability to around 10-15 metres cubed per hour which is a good low cost way of reducing your heating bills.
 
The EPDM is supplied as 2 coils which are joined not one continuous length - these when separated equal the purchased length