[SystemSafety] Grenfell Tower

[Peter Bernard Ladkin]

It looks as if the announced inquiry is going to be purely technical
https://www.theguardian.com/uk-news/2017/jun/29/grenfell-inquiry-chairman-martin-moore-bick

I think it is a good thing to have a purely technical inquiry concerning the causality. (The other
social, political and legal concerns I hold to be best handled separately.) The ICAO Annex 13
reporting requirements for civil aviation, and its associated organisations such as the NTSB, AIIB,
BEA, BFU and ATSB, have obviously played a significant role over the decades in turning civil air
transport into such a safe endeavor.

In this case, we have a product made by a reputable company, used in such a way that, with
hindsight, it was not in conformance with building law.

Just to be clear what I mean, the law (the Building Regulations 2010) says:

[begin quote]
External fire spread
B4. (1) The external walls of the building shall adequately resist the spread of fire over the walls
and from one building to another, having regard to the height, use and position of the building.
[end quote]
(
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/485420/BR_PDF_AD_B1_2013.pdf
p39)

The accompanying Guidance says:

[begin quote]
In the Secretary of State’s view the Requirements of B4 will be met:
a. if the external walls are constructed so that the risk of ignition from an external source, and
the spread of fire over their surfaces, is restricted by making provision for them to have low rates
of heat release;
b. if the amount of unprotected area in the side of the building is restricted so as to limit the
amount of thermal radiation that can pass through the wall, taking the distance between the wall and
the boundary into account; and
c. <stuff about the roof>
[end quote]
(op.cit., p40)

All that is about as goal-oriented as you can get. Then there is the process-oriented approach to
regulation/standards, which prescribes how you may go about construction. As a (possible) example,
consider what has been said to be a German regulation that such material as Reynobond PE may not be
used as cladding on buildings over 22m high (I don't know the regulatory environment here and
haven't checked this).

Recently, some buildings in Germany have been discovered with a sufficiently-similar cladding
construction using Reynobond PE that inspections have started generally and prophylactic measures
are being undertaken. I imagine that many buildings could have been completed before the particular
regulation above (if it is one) came into force.

This illustrates a general point about goal-oriented versus process-oriented
regulation/standardisation.

Goal-oriented is: "Do it whatever way you like as long as you achieve the goal"
Process-oriented is: "Do it this way or that way."

Suppose the goal is an absence, as safety goals usually are: "bad things" are not to happen. Then
goal-oriented regulation allows flexibility and innovation, but it can be weak if engineering
practice doesn't have a complete understanding of how it is that the "bad things" happen which has
been encapsulated in tests. Whereas process-orientation restricts practice, and thereby innovation,
but "we did it this way and it always worked" can be a more reliable way to avoid the "bad things"
in circumstances in which there is incomplete knowledge.

I think the pharmaceutical industry regularly deals with these issues about incomplete knowledge
concerning safety. You test drugs, try to gauge the side effects. You licence them for restricted
purpose, and when previously-unknown side effects turn up, you restrict further or withdraw the drug.

I can see that fire safety could be somewhat like that. I think we can say that there is incomplete
knowledge of how fire spreads through cladding structures, leading in turn to incomplete
standardisation and regulatory guidance. I think an inquiry of the sort common in civil aviation is
likely a right mechanism to begin to get that sorted.

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
MoreInCommon
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de





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