Building separation from relevant boundaries based on thermal radiation

A building should be separated from its relevant boundaries by at least half the distance at which the total thermal radiation intensity received from all unprotected areas in the external walls would be 12.6 kW/m2 (in still air) assuming the radiation intensity at each unprotected area is – (a) 84 kW/m2 where the building is of Purpose Group 1, 2, 3, 5 or 7(b); or (b) 168 kW/m2 where the building is of any other purpose group. Where a building is compartmented each compartment should be calculated separately. Where a building or compartment is fitted throughout with a sprinkler system in accordance with Section 8 complying with the relevant provisions of BS 5306-2 or BS EN 12845 for the appropriate occupancy, the thermal radiation intensities in (a) and (b) and the distances calculated using the methods given in paragraphs 5.16 to 5.19 may be halved subject to there being a minimum distance of 1 m. Alternatively, the amount of unprotected area may be doubled if the calculated boundary distance is maintained.