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Specific Fan Power Calculator
Ctrl+D to bookmark this toolCalculate SFP for Part L compliance. Check your fan selection against Building Regulations limits.
Specific Fan Power
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Enter values to check compliance
Formula: SFP = Fan Power (W) / Flow Rate (L/s)
Part L SFP Limits
SFP limits from Approved Document L, Volume 2: Buildings other than dwellings (2021 edition). Always verify against the latest published edition.
| System Type | SFP Limit W/(L/s) | Regulation |
|---|---|---|
| Central mechanical ventilation (specific) | 1.6 | AD-L Vol 2 |
| Central mechanical ventilation with cooling | 2.2 | AD-L Vol 2 |
| Local mechanical ventilation (supply or extract) | 0.5 | AD-L Vol 2 |
| Fan coil units | 0.8 | AD-L Vol 2 |
| Terminal units | 1.2 | AD-L Vol 2 |
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