Hospital Design



Unable to evacuate
Fire safety in healthcare buildings
 

Healthcare buildings, and in particular hospitals, present building designers with a different challenge in terms of fire safety design when compared to other building types. The fire safety design of buildings as diverse as hotels, offices, factories and sports stadia assumes that occupants within the building are able to evacuate themselves from a building in the event of a fire. In healthcare buildings this is not always the case. Richard Rankin, a senior fire engineer, looks at this issue.

In healthcare buildings, particularly in patient access areas, the immediate and total evacuation of the building in the event of fire may not be possible or desirable. Patients with restricted mobility, patients who use wheelchairs, and patients confined to bed, cannot negotiate escape routes, particularly stairways, unaided. Patients under medication may require staff assistance, and patients who are dependent on electrical or mechanical equipment for their survival cannot always be disconnected and moved rapidly without serious consequences.

The basic strategy for fire evacuation of dependent or very high dependency patients should be to move them on their bed or in a wheelchair, to a safer area on the same floor.




There are three main stages of evacuation (which are adopted as the circumstances dictate):
● Stage 1 – horizontal evacuation from the sub-compartment where the fire originates to an adjoining subcompartment or compartment
● Stage 2 – horizontal evacuation from the entire compartment where the fire originates to an adjoining compartment on the same floor
● Stage 3 – vertical evacuation to a lower floor substantially remote from the floor of origin of the fire (at least two floors below), or to the outside

There are three fire conditions which determine when evacuation is necessary or should be considered:
● Extreme emergency – where there is an immediate threat to safety from fire or smoke ● Emergency – no immediate threat, but fire or smoke is likely to spread from an adjoining area
● Precautionary – no immediate threat to life or safety, but there is a fire on an adjoining floor or in an adjacent building

In extreme emergency situations, the sequence of evacuation should be:
● Those in immediate danger
● Ambulant patients
● The remaining patients who are not ambulant

Horizontal evacuation

The strategy outlined above is commonly known as ‘progressive horizontal evacuation’ and is referenced in international design codes, such as NFPA 101 Life Safety code and Health Technical Memorandum 05-02 (Health Technical Memorandum 05-02 is a Code of Practice prepared by a working group under the direction of the United Kingdom’s Department of Health’s National Fire Policy Advisory Group. It is a guidance document that recognises the problems special to healthcare).

The principle of progressive horizontal evacuation is that of moving occupants from an area affected by fire through a fireresisting barrier to an adjoining area on the same level, designed to protect the occupants from the immediate dangers of fire and smoke (a refuge). The occupants may remain there until the fire is dealt with or await further evacuation to another similar adjoining area or down the nearest stairway. This procedure should give sufficient time for non-ambulant and partially ambulant patients to be evacuated down stairways to a place of safety, should it become necessary to evacuate an entire floor.

High-rise hospitals

High-rise hospitals and those containing very high dependency patients present different challenges which may require additional fire safety provisions to combat the inherent problems with moving such patients. The time required for evacuation is longer, as it is often necessary to move the patient, ventilators, monitoring equipment and support staff as one unit, and the design should seek to maximise the protection to the patients allowing for extended ‘waiting to be moved’ and ‘travel’ times.

Firstly, the use of evacuation bed lifts within each compartment should be considered as a viable means of moving patients to lower floors within the building. Such a strategy should be considered particularly in high-rise hospitals where mattress evacuation down a significant number of flights would be extremely difficult. Since the capacity of any escape lift provision is unlikely to be enough to accommodate all occupants requiring evacuation by lift at any one time, sufficient areas of safe refuge should be provided to accommodate those that may be required to wait for the availability of the escape lift. Any refuge provision should take into account:

● The number of occupants likely to be awaiting evacuation by lift
● The number of occupants reaching escape lifts through progressive horizontal evacuation; and
● The capacity of the escape lift provision at that point (taking into account the space requirements for life support and other associated equipment for high dependency patients)

There are other emergencies such as bomb threats and earthquakes where evacuation of the entire building may be necessary. In such cases lifts can be used simultaneously with the exit stairs to reduce the time taken to evacuate the building particularly in highrise buildings.

Secondly, active smoke management strategies can be developed to prevent smoke spread into adjacent compartments or sub-compartments. Prescriptive guidance generally relies on fire and smoke barriers to contain the fire to the area of origin. The buildings HVAC system can be zoned and utilised to achieve pressure differentials between fire affected and adjacent compartments to further reduce the risk of smoke spreading from the compartment of fire origin. Such an approach would be particularly beneficial for operating theatre departments where movement of a patient may be life threatening. The combination of passive (fire and smoke barriers) and active systems (pressurization of compartments adjacent to the fire affected compartment, sprinklers) may allow such patients to remain in-situ.

Staff training

Staff training forms an essential part of the fire strategy in healthcare buildings. Staff should be familiar with the concept of progressive horizontal evacuation. Staff need to have an understanding of fire risks and know what to do in the event of a fire so that fire safety procedures can be applied effectively. It is therefore imperative that healthcare organisations provide appropriate levels of fire safety training. This applies to all staff without exception including temporary and part time staff. A fire safety manual should be developed to assist in this regard to identify the design intent of the building and the roles and responsibilities of management in an emergency evacuation. All staff shall be trained when they first join and refresher training shall also be provided to all staff periodically.

A fire safety manual is an essential tool in managing the fire safety of an occupied building. It should contain both design information and operational records for the premises. The manual should initially be created by the design team (for new buildings), as it needs to provide details of assumptions and decisions made during the design stage which led to the final building design. This should include explicit assumptions made in respect of ongoing management arrangements once the building has become occupied.

In summary, good fire safety design of healthcare buildings requires a combination of passive (compartmentalisation and sub-compartmentalisation by fire and smoke barriers and the arrangement of these compartments to allow progressive horizontal evacuation) and active (automatic fire detection, automatic fire suppression, zoned smoke management and evacuation lifts) fire safety provisions, in addition to good management, training and understanding of the buildings fire strategy. It is essential that building designers consider the dependency of the occupants within the building, taking into account the location of any very high dependency occupants and providing appropriate provisions for such occupants.

● Richard Rankin is a Senior Fire Engineer with Exova Warringtonfire Consulting Middle East. richard.rankin@exova.com
 

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ate of upload: 10th Dec 2009

                                  
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