Down and out in safety
August 1st 2007

When evacuating people from a multi-storey building, should fire proof lifts be used in evacuation? Evac+Chair's Barry M Scholes takes a look at the case for and against Modern multi-storey buildings, (over 38 floors) are designed to incorporate a series of fire proof lifts which feature: Separate power supply, internal communication, pressurised lift shaft, smoke detection, smoke expulsion fans and fire wall protection.

The Case for Evacuation via fire proof lifts There is little doubt that where it is safe to use such lifts, this would be the fastest possible means of escape for all occupants of buildings. If the decision to evacuate is made, then a number of factors need to be understood: Where is the fire? What is the severity of the fire? Can it be contained? Petronas Twin Towers - KLCC A multi-storey building is often referred to as a vertical village, i.e. a mixture of accommodation, offices, shops and so on. In buildings such as the KLCC (Twin Towers in Kuala Lumpur) it is not uncommon to have well over 5000 people using each tower.

The KLCC has four fire proof lifts, four back-up power generators, pressurised stairwells, independently zoned sprinkler systems, a dual internal communication system, and CCTV. Its security team are the first responders who activate alarms, smoke proof doors and instigate the emergency evacuation plan. Due to the large number of employees in each Tower stairway evacuation is the main means of escape, using the two storey bridge to divert traffic to the adjacent building at the 41st and 42nd floor.

Persons with reduced mobility are escorted to the fire proof lifts, which are operator controlled.

The two fire proof lifts per tower serve as executive lifts and rise 390m in a single hoist at 5m/second. During normal service the time to ascend or descend from the 86th floor takes 70 seconds and has a capacity of ten persons per lift.

Each tower has a further 29 double-decker passenger lifts and three heavy duty service lifts. These lifts are designed to evacuate 13% of each tower's maximum 6000 strong office population to their destinations within five minutes, with a waiting interval of not more than 30 seconds.

The Case against Evacuation via fire proof lifts The primary function of the fire proof lift however, is to enable the emergency service to take control of the building from ground level. Based on information supplied: Where is the fire? What is the severity of the fire? Can it be contained? The fire controller will set up a second command post below the source of fire. For speed and access, the fire proof lift will be the preferred choice of vertically moving both equipment and fire fighters. In the case of Tower 1 of The World Trade Centre, the express elevators were not fully fire proof and were destroyed on impact by a fireball on 9/11.

Intelligent Buildings also have fire and smoke detection systems and parts of the building can be compartmentalised when either smoke or depressurisation is detected, thus cutting off lobbies, safe refuges and access to elevators. It is reasonably foreseeable that occupants within the building could become isolated and left awaiting assistance. In tall buildings we must assume that an evacuation lift will automatically be programmed to return to ground floor level. Therefore, those awaiting evacuation at other floors have no control over their escape. Call buttons are overridden, and should smoke be detected on any floor outside of the lift shaft then lift doors may not open (in order to protect occupants). In some cases the adjacent lobby could become isolated as compartmentalisation starts to close off hot zones. We can safely assume, that the use of fire proof lifts as a sole means of escape could put evacuees at risk, until a floor by floor search is carried out.

There is, therefore, a strong argument for alternative means of escape as part of the total evacuation plan. A stairway evacuation time of 15 seconds per floor is achievable, using, for example, a stairway Evac+Chair for the mobility impaired. This is normal walking pace. Using the Sky Bridge at KLCC, no one need be more than 10 minutes away from safety.

Duty of Care In an emergency situation, employers have a duty of care to provide employees with adequate means of escape. This includes: to provide adequate supplies of the necessary equipment to cope with any emergency; and to provide adequate training to use the equipment. Crucial, however, is the fact that these provisions must cater "even for the minority interest".

But what constitutes 'adequate' and 'care' if you have occupants with mobility problems? Adequate care is quite well defined by the legislation. It can be determined by the answers to a series of simple questions: Is it foreseeable that there might be a fire? Is it foreseeable that there will be difficulties evacuating employees with mobility problems if an emergency arises? If the answer to these questions is yes, an employer must consider how he can best provide for the care of employees in this situation.

Independent escape routes It is for this reason that different escape routes and means of escape are independent of one another. The revised, BS5588 Fire Precautions in the Design and Construction of Buildings Part 8: Code of Practice for Means of Escape for Disabled People, has a footnote clause which states: "Refuges are relatively safe waiting areas for short periods. They are not areas where disabled people should be left indefinitely until rescued by the fire brigade or until the fire is extinguished".

According to HM Fire Service Inspectorate, "The practical answer to the question of refuges for the disabled or indeed rescue for persons with other disabilities is that for a variety of reasons, no fire service can guarantee 100% to turn up at an incident... there is no statutory duty of fire services to fight fires or to carry out rescues."

In the London Fire & Emergency Planning Authority Fire Safety Guidance Note No 26, "The evacuation must be planned so as to be successfully carried out by the building occupiers without the dependence on assistance from the fire brigade, whose initial resources may be limited".

It would seem that the responsibility for evacuation lies with the building occupier, and that although fire proof lifts can be part of the evacuation plan, they should not be the sole means of escape.

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