When entering lighting calculation information in PartL, the results sometimes differ from the entered figure.
In a number of cases, the SBEM calculation engine makes use of the NCM modeling guide to ensure that data provided to the calculation engine is correct. This can sometimes involve replacing data in the calculation or applying a function to the inputted data to produce more reliable information.
Under these circumstances, the technical guide has this to say about how SBEM handles Lighting Wattage calculations:
Where a full lighting design has been carried out:Use the actual lighting circuit wattage, multiply it by the illuminance level for this zone from the Activity database, divide it by the illuminance level for which the lighting design was carried out, and divide it by the zone area.
Please also note, that the SBEM calculation engine employs banding when producing the General Lighting and Display Lighting table.
The banding is split into multiples of 50, with the cut off point being the centre of the current band. For example, you have a calculated figure of less than 25w, then zero will be displayed. If you have a figure between 25 and 75, then 50 will be displayed, etc.