A tall order

Every major city the world over seems to want more tall, iconic buildings. But how do you safely transport all the occupants up to the top and down again – and how do you ferry them out safely in an emergency situation? The received wisdom is to take the stairs. But many are not physically equipped to travel down 100 or more floors under our own steam.

What’s more, stairs are not a realistic escape route for disabled occupants. UK Building Regulations require certain steps to be taken, including the provision of lifts and ramps, to ensure no one is disadvantaged because of any physical handicap from reaching their place of work. When the fire alarm operates, it is acceptable under the regulations for these same people to be taken to a protected refuge, from where they can be assisted to safety by the building management team or, more likely, left in place until rescued by fire crews.

Fire authorities are now, rightly, taking a more aggressive stance with building managers and insisting they have measures in place to evacuate the building completely before help arrives. But how many buildings have sufficient trained staff available to quickly escort a number of disabled people down the stairs?

I think we need to re-think our approach to the evacuation of tall buildings. We have the capability and technology available, and it is time lift designers were given the opportunity to design systems that could be used with confidence during an emergency.

Obviously, there will be a cost, and some additional features will require incorporating into the design of the building. A sprinkler system will almost certainly be needed – though, arguably, these should be provided in all tall buildings anyway. Lift lobbies and shafts will need to be protected against the ingress of smoke, and lobbies will have to be large enough to accommodate a proportion of those evacuating. The lift car and machinery must be protected against fire and water ingress.

In taller buildings, staircases are generally only wide enough to accommodate the occupants of two or three floors – the fire floor and the floor, or two floors, above the fire. It is now recognised, however, that the complete and simultaneous evacuation of high rise buildings may be necessary in certain circumstances. In recent incidents, building occupiers have decided to evacuate en masse, rather than in a number of carefully planned phases, causing serious overcrowding in the stair cores.

Moving large numbers of people down 100 or more floors using the stairs wastes precious time in an emergency

Not every fire or emergency incident will affect or disable all of the lifts in a building, and sophisticated fire protection systems, allied with the protection measures described above, may in many circumstances enable one or more of the elevators in a building to be used during the evacuation phase.

Wasting time

Not everyone will want to use the lifts – we have been told for the past 30 years we should use the stairs. But moving large numbers of people down 100 or more floors using only a few staircases wastes precious time during an emergency. Meanwhile, fire crews will be using those same stairs to try to get to the seat of the fire – hardly a recipe for dealing swiftly with the fire.

There have been a few notable projects, such as the Petronas Towers in Kuala Lumpur, where the evacuation strategy has included the use of elevators and, typically, the floors above the fire are evacuated using elevators, with those below it using the stairs. This approach may not necessarily reduce the total evacuation time by a significant amount, but by cutting the number of people using the stairs at the upper levels, the fire crews’ work is made easier.

Over time, as this type of strategy becomes more widely used, our confidence in the reliability of lifts will increase and, ultimately, we could expect to see everyone evacuating by elevator. Contrary to popular belief, and given sufficient attention to design improvements, this could well become the best bet for ensuring the people we put on the upper reaches of tall buildings have a better than even chance of escaping safely from a fire.