This is a tricky one...
Fire protection to means of escape is typically designed only to protect for a fairly limited period of time. Forget any thought of "I'll have 30 mins to manage escape" - this is only the test rating and it may have nothing to do with how long the separation will last in a fire (particularly doorsets - which are commonly incorrectly installed, and the smoke seals are, in my experience, usually U/S).
When people 'risk assess' the use of a non-evacuation lift for means of escape, I've seen the following 'interesting' assumptions....
1) it is unlikely that there will be a power failure.
...however, it could be an electrical supply fault that caused the fire. Sprinklers could be going off elsewhere in the building - which could cause a power failure. It's a common Fire Brigade tactic to cut power, when they commence operations. It could be the power failure that caused the fire in the first place (e.g. hot kit losing its cooling). There will inevitably be other single points of failure in the power supply. All this can be risk assessed, but it requires a detailed knowledge of the systems involved;
2) Staff will carry out a 'dynamic' risk assessment to determine whether the lift is safe to use.
How do they know? Can they tell if smoke from the fire is leaking into the lift shaft elsewhere (it might be perfectly clear where they are)? Have they any appreciation of how fast a fire can develop in an enclosed space, and how fast smoke can move? To be able to assess a risk, you have to have the relevant training and experience. It's hard for me to see how non-specialists can ever be expected to take this sort of decision on the spot;
3) Power failure is the only reason why a lift won't work.
How about failure of the Building Management System, if there is one? These are commonly linked to the lifts, these days, and if the BMS falls over as a result of the emergency all sorts of 'interesting' things could happen to the lifts. If you do get smoke in the vicinity of the lift, the anti-finger trapping sensors could 'think' it's an obstruction and the doors won't close. The fire could affect the lift control circuits directly. There must be other failure modes that I haven't thought of...
I could go on. Personally, I was really disappointed to see the use of non-evacuation lifts mentioned in the guides with so little advice on how to assess whether they are acceptable or not - a real cop-out by the authors. This is a huge and growing issue for the Fire industry. So many premises managers are struggling to match the alterations they wish to make to improve accessiblity with robust, credible and practicable fire emergency management plans. There is little doubt that lifts other than those that fulfil all the criteria in BS5588-8 can have a role to play in this, but our industry must develop some cogent guidance to help those struggling to deal with this tricky issue. PEEPs are one answer, but are hard to make robust, and don't necessarily help visitors or members of the public (where they have access to the premises), especially it it's lightly staffed).
