Open plan flats with a sprinkler system and enhanced detection to LD1 can provide a level of safety at least as good as a similar Approved Document B compliant design, a new study reveals.

The study, published by the NHBC Foundation, recognises that there has been considerable commercial pressure on building control bodies to approve open plan designs without having any authoritative evidence-based research or guidance on them, which has resulted in inconsistency in both design and approvals.

The study looked at fire safety systems being used in the UK and internationally, and evaluated some of them using the BRE risk assessment model CRISP.  The main conclusions are:

• Open plan flats with a sprinkler system in accordance with BS 9251 or BS EN 12845 and enhanced detection to LD1 in accordance with BS 5839-6 can provide a level of safety at least as good as that of a similar Approved Document B compliant design

• Flat size and travel distance is not a significant factor up to the largest size considered in the study (12m x 16m), but this conclusion should not be extrapolated to larger designs without further analysis

• It is not possible to state with sufficient confidence that enhanced detection alone could satisfy the requirements of the Building Regulations

The report goes on to say that a fire engineered solution should consider all aspects including fire growth, smoke movement, detection, suppression, human behaviour and the interactions between them, and that without the consideration of human behaviour, fire models might not give an adequate measure of the risk.