Note: if assessing kitchen area extraction or ventilation please refer to convention 6.12
Where the fan power motor can be established from the fan nameplate or Building Logbook, Operation &Maintenance manual etc. during the site survey the established power will be used to calculate the SFP.
If the power rating of a fan is known in horsepower then it shall be converted using the approximation of 1horsepower = 746 Watts
Where specific fan performance details are not available, the W/l/s value shall be amended as follows forexisting buildings:-
For Local Mechanical Extract systems only
0.5 W/l/s - buildings built to 2006 Building Regulations (2007 in Scotland)
0.4 W/l/s - buildings built to 2010 Building Regulations
0.3 W/l/s - buildings built to 2013- Building Regulations (or later)
For Mechanical Ventilation systems, whether defined at system level or at zone level
2.5 W/l/s - buildings built to 2006 Building Regulations (2007 in Scotland)
1.8 W/l/s - buildings built to 2010 Building Regulations
1.6 W/l/s - buildings built to 2013- Building Regulations (or later)
In addition to any specific fan powers established from the above, the relevant additional components fromtable 36 below should be added by following the guidance in the 2013 Non Domestic Building ServicesCompliance Guide.
Table 36 Extending specific fan power for additional components in new and exisitng buildings
| Component | SFP (W/(l.s)) |
| Additional return filter for heat recovery | +0.1 |
| HEPA filter | +1.0 |
| Heat recovery - thermal wheel system | +0.3 |
| Heat Recovery - other systems | +0.3 |
| Humidifier/dehumidifier (air conditioning system) | +0.1 |
The energy assessor should provide in assessment notes the reason why specific fan performance is notavailable.
Mike Gordon
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