Floor Warden: new evacuation lifts

 In Techniques

We are introducing the Floor Warden (FW) lift as a new concept for evacuating building occupants with the help of lifts. Existing evacuation lift concepts have the lift controlled either by an assistant present in the car, or, when not by an assistant, then supervised by external Building Management System (BMS) and monitoring thus allowing self evacuation. The FW concept on the other hand allows the lift being controlled by a member of the Emergency Response Team (ERT) who is present on the floor that will be evacuated. The advantage of this concept is that there is no need to appoint an extra ERT member exclusively for controlling the lift. Therefore it makes more efficient use of the ERT organization. On top of that the lift capacity is also used more efficiently, because 100% of the floor area is available for occupants that need to be evacuated. Based on this concept we developed a system that can operate fully independent from external building systems, and has its own integrated intercom. It is therefore easy for implementation in new or existing buildings. The system that we developed appears to be very simple in use. Details of the concept and its development are discussed in this paper.

1. Introduction
Today the lift industry knows a few different concepts for the application of lifts for evacuation of buildings in the case of an emergency. We have made a comparison of a few of these known concepts [1]. And we noted that the possibilities that current concepts allow are rather restricted. For example, none of the concepts allows that during an evacuation the lift will be controlled from the landing that needs to be evacuated. Therefore we developed such a concept under the name of the Floor Warden concept. This article describes the background and development of the concept of the Floor Warden control system for an evacuation lift.

2. Existing concepts for evacuation lifts
Lifts have been used for evacuation very occasionally for a very long time due to some accidents in the past. Nevertheless, with the coming of the Lifts Directive discussions started in Europe about the possibility to standardize the requirements for such lifts, with a strong focus on evacuation of disabled persons. After the 9/11 disaster new discussions started in North America. In a relatively short time this has resulted requirements about evacuation with lifts in the International Building Code and in the ASME A17.1.

We made a comparison of five concepts that we know today as state of the art. Four of these concepts are described in standard or code documents [1]:

In force:

  • BS 9999, describing a control from inside the lift car for evacuation of disabled persons, close to the control system of firefighter lifts as in EN 81-72 [2]BS 9999, describing a control from inside the lift car for evacuation of disabled persons, close to the control system of firefighter lifts as in EN 81-72 [2]
  • ASME A.17.1 describing an Occupant Evacuation Operation mode under supervision of a BMS, allowing building occupants that are close to the emergency to evacuate themselves with the lifts, while monitoring the safe environment and functioning of the lift. [3]

Under development:

  • CEN/TS81-76, describing a system similar to the principle as BS9999, namely controlled from inside the car as EN 81-72 firefighter lifts, but with the restriction of small buildings [4]
  • ISO/DTS18870, describing a system similar to the principle as in A.17, namely un-assisted self evacuation, depending on the input signals a BMS. [5]

A fifth concept is often referred to as the lifeboat principle [6], which is applied in various very tall buildings such as Petronas Towers and Burj Khalifa. In this principle the occupants from the higher part of the building gather at an intermediate refuge floor. From this floor the lifts shuttle up and down towards the main evacuation exit floor.
While the four concepts which are described in code or standard documents are focusing on the way that the lift is controlled, the lifeboat principle on the other hand is rather a way of application than a way of controlling (Table 1).

3. The Floor Warden Concept

3.1 Basic concept: Control by Floor Warden
The basic concept of the Floor Warden (FW) lift is that an appointed Floor Warden will control the lift from the floor that needs to be evacuated, instead of the lift being controlled from inside the car. The Floor Warden is most likely a member of the ERT that is in many countries required in buildings with commercial or public function. The reason to apply this principle of the Floor Warden control is that it immediately gives many advantages over existing principles:

  1. Efficient use of ERT organization: There is no need to appoint an extra ERT member exclusively for controlling the lift. So, the staff of the ERT organization can be used more efficiently.
  2. Panic control: by controlling the lift from the landing, it will be easier to reassure occupants that remain on the landing if the car is full. And in the worst case it will allow the floor warden to keep persons away from the landing doors while closing.
  3. Reduced psychological work load: In the existing concepts of CEN and BS the one person in the car has a complex task with large responsibility. This is reduced.
  4. Saving car space: the lift capacity is used more efficiently, because 100% of the floor area is available for occupants that need to be evacuated.
  5. Wide range of applications: our concept relates to a way of controlling the lift, but it is not restricted to certain application. For example it can be used for small buildings serving each floor for evacuation of disabled persons. But it can also be applied as the control system for lifeboat lifts that are used in tall buildings for evacuating occupants from intermediate refuge floors.
  6. Simple low threshold system independent from a BMS or alike: In addition to above intrinsic advantages of the principle, the principle also allows to create a system that can (when needed) operate independently from external systems such as a BMS. In order to keep this independency we also included a fully integrated intercom system.

3.2 Operation
n our concept the Floor Warden can directly gain control over the lift by inserting a key in the FW key-switch of the FW panel on the landings, and operating that switch (Figure 1). This will bring the lift into the FW control mode, overruling all existing commands, and ruling out any new commands. The lift will first bring any passengers to the Main Evacuation Exit Floor (MEEF), and will then be automatically sent to the Floor Warden who has operated the FW key-switch.
From that moment on this Floor Warden can evacuate the occupants from his floor. He will ask the occupants to enter the lift. When done, the Floor Warden closes the door while staying at the landing. This will allow the Floor Warden to reassure the remaining occupants, and in a worse case it will allow the Floor Warden to avoid panicking occupants to rush into the lift and thus hindering/preventing the doors of the lift to close.
In our prototype the doors are closed by continuously pushing the hall buttons, which temporarily got this alternative function for this purpose. Another option which we patented is to use the FW-key switch, but at this moment we didn’t apply this embodiment in our concept. In any case it is important that the door closing can only be achieved by continuous operation, because this forces the Floor Warden to stay on the floor, and it prevents him or her to leave the floor while keeping the priority to that floor.
When the passengers are released at the MEEF, the lift automatically returns to the Floor Warden who has control. This sequence can be repeated until that floor is fully evacuated. Before making the last trip to the MEEF, the Floor Warden switches back the FW key-switch to the normal position. This will allow him a short time to also enter the car, and evacuate himself. When the lift has arrived at the MEEF after this last ride, the lift will return to normal operation, or if another Floor Warden has requested the control, the lift will be sent to the next Floor Warden in the waiting queue.

Waiting Queue

The FW control system is designed to have multiple FW panels at various floors. As a result more than one Floor Warden may call for priority control, and a waiting queue will thus occur. The waiting queue will be regulated by the following 2 principles: The Floor Warden who operates the FW key-switch first, will get first priority. Next Floor Wardens will be served by the height of the floor: the highest floor will be next in line. Through signalization the floor wardens will be informed about the existence of a waiting queue. Three different situations can be informed:

  • no waiting queue;
  • one Floor Warden waiting for control;
  • more than one Floor Warden waiting for control.

3.3 Fully integrated intercom system
Whereas the existing concepts depend on an intercom system that is not always part of the lift, we have chosen to provide a fully integrated system into the FW concept. It is of extreme importance that communication is well organized in order to prevent misunderstandings and confusion, and most of all in order to prevent panicking. Therefore each floor where a FW panel is provided, also an intercom is provided allowing 2-way communication with the passengers in the car. And also 2-way communication between the Floor Wardens is possible for their coordination if needed. Passengers in the car do not need to press a button. During the emergency, when the lift is in the FW mode, the Floor Wardens can always hear what is going on in the car, and what the passengers have to say. On the other hand, if a Floor Warden wants to use the intercom he/she will have to push the ‘talk’ button first. While pushing, his voice message can be heard in all the other stations connected to the intercom system, both on the landings and in the car.

3.4 Options at MEEF: recall switch or firefighter panel
At the main landing we have the possibility to install a switch that can overrule the FW mode, and recall the lift to the MEEF. This is an option that might be requested by the local Fire Brigade. And another option is to combine the FW lift with the function of a firefighter lift. In this case the complete lift will comply with the EN 81-72. This will be indicated by the marking, the firefighter lift pictogram near the Firefighter switch at the main landing. Operating the firefighter lift switch will overrule FW control and allow firefighter service Phase 2 as described in clause 5.8.8 of EN 81-72.

3.5 Protection
Our concept mainly is focusing on the control of the lift. On the other hand it is essential that the functioning can be ensured especially if the emergency consists of a fire in the building. Therefore the protection of the lift, and of the power supply should be at least of the same level as applied for firefighter lifts. In addition some basic monitoring is part of the concept, and the controller is ready to receive signals from external monitoring devices that might detect dangerous situations needing to take the lift out of service in the extreme case. However, if the lift is installed in the same compartment as the safety staircase is, it can be assumed that a sound safety level is achieved.

3.6 Power supply
Same as the environment, also the power supply shall be similarly protected as is the power supply of firefighter lifts. In addition a battery system brings the passengers to the nearest landing if a power failure still occurs.

4. Applications
The FW control system can be applied in different manners, and in a wide range of buildings.  The only limitation that we currently have is that there must be some kind of rescue organization, often referred to as ERT. For example it can be applied in small buildings, when there is a need to evacuate disabled persons who cannot take the stairs. In that case a FW panel should be installed on each floor. Another application, which fits perfectly to the FW control is the application as for the lifeboat principle in very tall buildings. And finally we believe that our FW system may lead to an in-between-solutions that we are not seeing at the moment, namely by providing plural intermediate floors at a repetitive/ intermittent pattern. In such case building occupants can walk a few stairs and then take the elevator. This would be a great help for occupant who have poor mobility such as elderly.

5. Development process
In the following we will describe the development process. This consisted of the following steps:In the following we will describe the development process. This consisted of the following steps:

  1. defining the scope
  2. making a risk assessment
  3. develop safety measures
  4. making of prototype
  5. reviewing of prototype with possible users and experts
  6. revise/update risk assessment
  7. finalizing the design in Technical Construction Files / TCF
  8. type Certification by notified body.

Steps 1-7 can be regarded as iterative steps: previous steps sometimes needed to be done again as result of the outcome of a later step.

5.1 Risk assessment
One of the responsibilities that we have when we develop a new system is to assess all the risks that may result from the concept and final product. Throughout the development process we registered all the risks that occurred or that we became aware of. We assessed the risks and took measures if needed. Where the modified design would result in new risks, these risks would be assessed in the same manner. The risk assessment and the taken measures were registered in the way that is described in the EN ISO 14798.

5.2 Prototype & Review
The development of the concept has been in cooperation between engineers from the development department in Japan, and engineers from R&D Centre in Veenendaal, the Netherlands. The prototype has been built in a test tower at the factory site of Mitsubishi Elevator Europe in Veenendaal, the Netherlands. The prototype has been reviewed by internal and external persons, by members of an ERT, and representatives of fire services from different regions. Based on these reviews we could further improve the system, and where needed we updated the risk assessment.

5.3 Type certification
We have asked notified body Liftinstituut to examine our concept and certify it on the basis of the Lifts Directive. As there is no harmonized standard for this kind of lifts yet, the certification took place on the basis of related standards where possible. In addition we made an extensive risk assessment that was also examined by Liftinsituut as part of the certification.The relevant part of the Lifts Directive for this kind of lifts can be found in Annex I, article 4.10 which contains the Essential Safety Requirement (ESR) for lifts that are intended to remain in service during an emergency.For certain aspects of our concept the related harmonized standards could be used as reference. These harmonized standards that are linked to ESR 4.10 are:

  • EN 81-72 with respect to Firefighter lifts
  • EN 81-73 with respect to lifts that are put out of service as result of a fire alarm.

In addition reference is made to CEN/TS 81-76, a Technical Specification (not a standard) that deals with lifts intended for the evacuation of disabled persons from simple low rise buildings.

6. Pro’s and con’sof the Floor Warden concept

6.1 Advantages

  • i) No need for assistant in the car
    The main advantage of the FW concept is that there is no need for a trained assistant to stay in the car and control the lift during the evacuation process. Not only does it save manpower / capacity of the ERT, but also we can assume that the ERT member who has to drive the car would have a relatively big responsibility, and thus psychological burden. After all: he is the person who in the end controls the car and picks up the remaining occupants in a certain order of priority. So, by omitting the need for an in-car assistant, the ERT team is relieved from quite a burden, and the manpower of the ERT can be applied more efficiently. But not only is the capacity of the ERT used more efficiently, also the capacity of the car is used more efficiently: the full capacity can be used for evacuation of occupants. No extra space in the car is needed to transport the assistant.
  • ii) Panic control
    By controlling the lift from the landing, it will be easier to reassure occupants that remain on the landing if the car is full. And in the worst case it will allow the floor warden to keep persons away from the landing doors while closing.
  • iii) Very simple in use – very suitable for ERT
    The controlling of the lift is very simple, almost intuitive. This was what we could conclude during the review by various persons. Also this will make it very suitable for the ERT organization. Many buildings have an ERT organization, as in many cases this will be a legal obligation, e.g. for the employers (companies or other organizations) that are using the building. We believe that the FW concept is very suitable for such ERT organizations, even for existing ones.
  • iv) Self dependent – no external systems required
    The other systems that we know today all depend in some way on systems that are part of the building. The systems described in BS 9999 and TS 81-76 depend on an intercom system that is part of the building. The automatic system as described in ASME A17.1 and ISO 18870 depend on sophisticated monitoring and BMS systems.  The FW concept on the other hand is fully self dependent. It has a fully integrated intercom system allowing communication between all the places where passengers and floor wardens may hold up. And – although interaction with a BMS system and/or monitoring is possible, it is surely not required.
  • v) Low threshold – easy implementation/application
    All above advantages result in another big advantage: the system has a low threshold for implementation: very suitable for existing ERT without big impact; no need for third party systems (building intercom, BMS); very simple in use. This makes it a system that can be easily applied in existing buildings, but also architects and building planners can easily incorporate the FW system in the design of the building; they don’t need to worry about making the building more complicated, and therefore also no worry to have objections from other parties.

6.2 Restrictions of the floor warden concept
The main restriction of the FW concept is that it can only be applied where a certain level of protection can be assured on one hand for power supply and on the other hand protection of the shaft and lobbies against fire and smoke. But this is a restriction that applies for all the lifts that are used for evacuation. The other restriction is that the lift is basically only intended for buildings where some kind of ERT or similar organization is present.

7. Evacuation Lift Market
In the future we will see a growing need for lifts that can be used for evacuation in the event of an emergency. In some countries there is already law that is asking for such lifts, and sometimes even recognizing lifts as a way to reduce capacity of stairs. For the FW lift we see highest potential in office buildings and buildings in the care segment, but also in the other segments, as long as ERT is organized. However, it is imaginable that even in the residential segment there is some potential, although this would require some safety measures resulting from additional risk assessment.

8. Conclusion
With the Floor Warden concept we believe that we have added an interesting concept which offers a wide range of new possibilities for building owners and architects when it comes to using lifts for evacuation. We believe that this concept has added value compared to existing concepts, and can be applied in combination with those existing concepts can be a low threshold alternative for those concepts.We hope that this concept will help to bring forward the discussion about application of lifts in case of an emergency. In the end, bringing occupants out of a building safely is a goal that the lift industry should aim at.

9. References
[1] Wim Offerhaus, Ashiqur Rahman (2014): Comparison of Concepts for Evacuation Lifts, Elevator Technology 20,p.p.74-83. [2] American Society of Mechanical Engineers (ASME) (2012). A17.1: Safety Code for Elevators and Escalators. [3] British Standards Institution (BSI) (2008). BS9999: Code of practice for fire safety in the design, management and use of buildings. [4] European Committee for Standardization (CEN) (2011). CEN/TS 81-76: Evacuation of disabled persons using lift. [5] International Standardization Organization (ISO) (2012). ISO DTS 18870: Requirements for lifts used to assist in building evacuation. [6] Fortune, J. W. (2010). Emergency Building Evacuations via Elevators. CTBUH World Conference, Mumbai, India, February 3-5.

10. The Authors

Wim Offerhaus graduated in 1993 as a M.Sc. in Industrial Design Engineering at the Technical University of Delft. Since 1997 he works for Mitsubishi Elevator Europe B.V. in Veenendaal, The Netherlands at the R&D Centre. Wim Offerhaus is a member of CEN/TC10/Wg6 and Wg1, and also of the national standardization committee for lift standards in The Netherlands.

Ashiqur Rahman received M.Sc. in Mechanical Engineering from University of Stuttgart, Germany in 2004. Since 2009 he works for Mitsubishi Elevator Europe B.V. in Veenendaal, The Netherlands at the R&D Centre.

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