Rytons Background Ventilation Calculator

Background ventilation calculator for habitable rooms

This handy ventilation calculator will provide you with a total equivalent area requirement for any property using System 1 of the Building Regulations, Part F.  The calculation should then be used in conjunction with the finer details contained within Part F.

Please note:

  • Background ventilators should be located in all rooms with external walls.  Once the total requirement has been calculated, at least 5000mm² equivalent area is required in each habitable room and 2500mm² equivalent area is required in each wet room.
  • Background ventilators should be sited to avoid draughts.  This can typically be achieved at a position of 1.7m above floor level.
  • We are always happy to assist you with product selections, call our technical team on 01536 511874 for advice.
  • We have a comprehensive range of acoustic ventilators available for sites and properties with noise problems.

Make a calculation:

Total Floor Area (m2):   
Dwelling Type:    Single-storey located up to and including the fourth storey above ground level
Multi-storey, and single-storey located more than four storeys above ground level
No. of Bedrooms:   
Design Air Permeability:    Type A: Any design air permeability
Type B: Design air permeability leakier than 5m3/h.m2 at 50 Pa
Facades:    Single facade (one exposed facade only)
Multiple facades (two or more exposed facades)


Rytons is proud to be a family run business and British manufacturer since 1972.