16/7/2020
The Grenfell Tower fire in 2017 was a wakeup call for everyone involved in fire safety and much more attention is now being paid to fire safety. It was only at the end of last year that Efectis realised for the first time that we regularly receive requests to assess façade systems.
In the Netherlands, the SBI facility is used to assess façade structures, in combination with a supplementary assessment. To determine the fire safety of a façade a fire spread calculation is made in accordance with NEN 6068, showing whether the façade is safe. This involves assessing the façade materials used in accordance with the Buildings Decree, Section 2.9.1. The exterior skin of the building will have to comply demonstrably with fire class B, by the submission of results of tests on the materials used. This relates to the specific separate materials and a combination of materials. Both have to comply with fire class B.
It regularly went unnoticed that, in practice, where materials were assessed as class B, a combination of those materials were automatically rated as class B as well. The Grenfell Tower fire has made us wiser but we have also shed one of our illusions.
Consequently, many architectural practices are now more aware that a combination of the right materials can lead to fire spread and/or fire propagation along the façade. In particular, the use of all kinds of exotic materials and structures in the interests of the sustainability of construction has made these buildings more aesthetically pleasing (for instance green façades, possibly with solar panels for power generation), but at the expense of fire safety. In the last six months, we have tested several façade structures, with surprisingly poor results. In particular, open-joint ventilated façade systems performed worse than would have been expected.
Although some of the structures achieved the ultimate aim of compliance with class B, others were rated as class E or lower. These results have made it even clearer that assessment of these structures is needed.
In the Dutch situation, where the fire safety of façades is determined by means of the SBI test method in combination with the assessment, the results of the SBI test are sometimes satisfactory but doubt exists with regard to the final assessment. So larger-scale testing is needed.
For this reason, a lot of hard work is currently going into putting the finishing touches to our Room Corner setup in the Ad-Hoc test facility, modifications which have taken the form of an extra-large exhaust hood in combination with a Heat Release Rate system to be able to determine large capacities. Under this large exhaust hood, we can intermediate-scale test in accordance with ISO 13785 part 1. The main reason for this is the long waiting time at fire labs throughout Europe and extra attention being paid to façade safety. It will enable us to very soon give a better opinion about the façades.
Contact: Arjo Lock [arjo.lock@efectis.com]