In my opinion this is one of the most ignored issues faced in fire risk assessment - and perhaps in design too.
Evac chairs are a low capital cost option for vertical transportation of Persons of Restricted Mobility (PRMs). The issues:
- if the person being evacuated is in their own wheelchair & has severe impairment, you have to physically transfer them to the evac chair. PRMs might foreseeably be heavy. Therefore your emergency plan ought to state how you ensure you have enough fit, trained staff available to do this, without unreasonably delaying evacuation. They should be trained to safely transfer people, not just to move someone conveniently already in the evac chair. Advice varies as to the minimum number of people you need to do this safely, but in my experience it's at least two, sometimes three (for the transfer - not for the vertical movement, which I accept a single person can manage). This minimum number normally has to be available at all times when the building is occupied.
- they might have to do this multiple times (especially in a public building);
- I'll leave the debate about whether showing someone a video of how to use a chair and/or do the transfer is an effective training tool on its own for another time. What I will say is that in my experience H&S managers are generally unhappy about the manual handling risks associated with go-see-do training involving transfer from wheelchairs into evac chairs.
We design a lot of public buildings, & when I sit down with the management and we go through these issues they almost invariably decide that they want to avoid relying upon evac chairs. We're therefore specifying more and more evacuation lifts for low-rise buildings. Capital cost is higher, but reduced staffing costs sometimes compensates (bearing in mind that in public buildings if your emergency plan invokes minimum staff numbers then for every extra person you need you might need 4-5 more employees, to cover shifts & absences). Whole-life cost and reduced manual handling risks makes the case for the lifts somewhat more straightforward (especially as designers often over-specify evacuation lifts - if you get the configuration of stairs, refuge and lifts right then the cost for the additional systems - power supplies etc - is pretty minimal)!
Existing buildings are, of course, much more tricky and there is often no easy answer. We normally try very hard to make a case why the existing lifts can be used (usually with some modifications). Lifts with reasonably modern lift controllers can be tricky, because if they comply with BS EN 81 then when the fire alarm goes off the lifts won't work - no matter what you do with the car or landing calls (including any key switches). Lift Engineers are very reluctant to program them any other way, stating that compliance with the ENs is effectively a legal requirement for them. LFEPA have been discussing this issue with the relevant lift industry bodies, so far as I understand.
As an industry we really haven't dealt with this well - placing a piece of bent steel and canvas in a refuge and stating that the building occupants need to come up with a PEEP explaining how to use it has been an easy-out - technically it works but it often has huge management implications where you can't be sure what degree of mobility impairment you might have to deal with, nor how many people you might need to evacuate. My prediction... in 20 years time we'll wonder how we ever convinced ourselves it is OK to build multi-storey buildings without evac lifts!