Mechanical
Ventilation Rate Calculator
Estimate ventilation rates for dwellings, non-dwellings and schools using common compliance-based methods.
Use this calculator for early-stage ventilation checks based on common UK compliance and design approaches. It includes dwelling, non-dwelling and school routes, with occupancy and ACH-based options where appropriate.
Inputs
Result
Ventilation Rate
-
Enter values and click calculate.
Method
Different building types and design routes use different methods to establish the required outdoor air rate.
Ventilation Rate = Occupants × Outdoor Air Rate
Where an ACH method is used:
Ventilation Rate (m³/h) = Room Volume × ACH
Conversion between units:
Ventilation Rate (L/s) = m³/h ÷ 3.6
- Dwelling: use the higher of bedroom-based minimum rate and 0.3 L/s per m² of internal floor area.
- Non-dwelling office: use the higher of 10 L/s per person or 1 L/s per m².
- Occupancy method: ventilation rate = occupants × L/s per person.
- ACH method: ventilation rate (m³/h) = room volume × air changes per hour.
- Calculated result = -
Reference
- This calculator provides an indicative ventilation rate based on the selected building type and calculation route.
- For dwellings, relevant guidance may include Approved Document F Volume 1.
- For buildings other than dwellings, relevant guidance may include Approved Document F Volume 2.
- For schools, final ventilation requirements should be checked against BB 101 and the project-specific school brief.
Design note: This calculator is an early-stage estimating tool only. Final requirements may also depend on building use, pollutant loads, extract strategy, ventilation effectiveness, thermal comfort, project-specific criteria and the agreed compliance strategy with the design team and building control body.