As our population in Australia and around the world continues to grow, so do our cities and major regional hubs. Growth is not only horizontal, but the vertical construction of tall buildings that we work, reside, visit and even holiday in, continues to increase.
The variety of occupants merged into a single structure creates challenges on how we manage emergency situations. Whilst fire has traditionally been the major hazard in high-rise buildings, we now need to factor in technological failures, weather events, natural disasters, chemical incidents, terrorist related situations and active shooters. All of these incidents require a different response applied to the wide variety of occupants who all have different levels of knowledge and capability.
Evacuation methods from large structures have evolved. They now must be capable of managing mixed occupancy combined with a range of hazards applied to an ever-changing building design.
- Do we really want to stage people in a large group at the base of a building?
- Is it achievable for people with mobility challenges to evacuate down long stairwells?
- Why are we not embracing technology like mobile phones to manage communications during building emergencies?
Key points in relation to evacuation include:
- When a building contains minimal redundancy in the fire safety design, the need to evacuate in times of an emergency are increased.
- Evacuation drills are done to evaluate how long it takes people to get out or to educate the occupant through a rehearsal. By trying to do both, we may not be successfully achieving either. People need to be trained on an individual level, not just walk down stairs.
- The speed of evacuation is determined by the slowest person in the stairwell.
- Mobility challenged evacuation is not always factored into the evacuation speed for a building.
Occupant Evacuation Lifts/Elevators
There is an identified need to increase the use and installation of purpose-built occupant evacuation lifts in all future building development. The number of people occupying buildings who have mobility challenges have been identified to be between 8% to 13% and those with no ability to use stairs between 2% to 3% (Boyce, 2014). With ageing populations increasing, there will be a reduced capability of people occupying high-rise buildings who can walk down stairs for long distances. A heavily pregnant lady, a person carrying a temporary sports injury, a person with a heart condition, someone who is an asthmatic, a family with young children, an obese person, an elderly person with reduced mobility, a person in a wheel chair will all have reduced evacuation capability.
Evacuation chairs widely used in the U.K are a possible solution to assist in providing assistance during evacuation, but this method is reliant on the device being available, maintained and a person capable of using it during an emergency.
The U.S Standard for Occupant Evacuation Lifts/Elevators, International Building Code (IBC) 2012 and the International Organisation for Standardisation (ISO) ISO/TR 25743:2010 is certainly the gold standard in lift evacuation. The challenge in the United States is this standard of occupant evacuation lift has not been installed in large volumes.
Some of the additional measures required in the IBC and ISO include:
- Lift system interlocked with the fire detection system
- Back-up power to all lifts
- Sprinkler protected building
- A method in preventing sprinkler water ingress into the lift shaft
- Fire rated lift shafts
- Larger lobby/refuge areas to ensure the safe area next to the lift can accommodate 25% of people on the floor and one wheelchair space for every 50 people.
- Automated operation with manual override for management and or fire service
- Enhanced signage
- Two-way communication system
181 Freemont St, San Francisco is one of the more recent examples of occupant evacuation lifts in the United States. Sweden and Finland have started to incorporate aspects of lift evacuation and in a format that may be considered more achievable. Building occupants will require education and information.
Alternative Means of Escape
A large range and variety of alternative means of escape methods are evident in numerous countries. Whilst all of these alternative methods have advantages and disadvantages, they do actually achieve their purpose: an alternative means of escape from a building when the main method is not available.
- Tokyo – escape ladders and helicopter pads for evacuation
- Singapore, New York and Boston – external fire escape stairs and ladders
- The Evacuator, an external emergency escape device utilising a wire cable, harness and a self- descending device.
- Escape hoods, an emergency hood used for protecting occupants from smoke contaminants.
- Sky bridges – the provision of an alternative exit pathway into another building via a constructed horizontal walkway.
Refuge floors were observed in Shanghai and appear to be heavily incorporated into building design across parts of Asia, including Hong Kong. With the increasing heights of high-rise buildings, refuge floors have become a common requirement across China for buildings above 100m of height as per the China National Code. There are structures around the world that can now take an able-bodied person over 1 hour to walk down the stairs. Refuge floors do provide potential benefits during evacuation, but also have a range of limitations.
Challenges associated with refuge floors include:
- Generally untested in relation to human behaviour. Would people remain in place during a real incident?
- People need to be physically capable of proceeding to the refuge floor.
- A refuge floor is not a cost-effective use of all available space.
- A refuge floor relies heavily on management being trained and capable of handling an emergency situation.
Evacuating to disperse and utilising technology
Evacuating to disperse occupants is starting to become a viable option when managing large crowd numbers. Traditionally, evacuation has always been to a designated location or assembly area, but the suitability of these locations to support large volumes of people in heavily built up areas has become difficult. The evacuate to disperse method also reduces the potential terrorist target of large crowds gathered in congested locations.
Communication forms a crucial element in how people are managed in emergency situations and the use of mobile phone messaging can assist. The Massey App and Wireless Emergency Alerts widely used across the U.S are examples of this technology.
Future evacuation challenges
- Increased complacency
- Mixed occupancy
- Physical capability of occupants
- Reliance on passive fire systems and the quality of their initial installation and ongoing maintenance.
- Fire Department capability to interact and assist with evacuation.
- Lift evacuation and occupant awareness
- Evacuation from construction sites
- Evacuation through bollards and obstructions
- Technology failures
- Missteps and falls on stairwells during evacuation because of increased mobile phone use and poor observation
Building – fire and life safety rating
When it comes to improving building fire and life safety, proactive change is what we need to aim for and the solution of implementing a Building – Fire and Life Safety Rating (B-FLSR) system could assist.
We rate buildings for environmental efficiency, we rate cars in Australia and N.Z for safety through the ANCAP Rating, we rate buildings in New Zealand with an Earthquake-prone Building Rating System, we rate food for its health properties, we rate movies and restaurants, yet most people are ill informed on the level of fire and life safety installed within the building in which they reside.
Buildings are built to meet standards, but they are predominantly designed to meet the minimum standards. By applying a B-FLSR, the purchaser and the occupier would be informed on the level of fire and life safety they are looking to invest in or reside. The B-FLSR has the potential to be applied to the many 1000’s of ageing buildings around the world, built to older standards and codes. The B-FLSR would act as an incentive for buildings to go above existing standards, act as guide to the occupier, create a market demand requiring higher ratings, potentially reduce insurance premiums for higher rated buildings and create incentives for retrofitting and improving existing buildings.
As the Grenfell Tower fire occurred in the early hours of the 14th June, 2017 in London, there were a number of fire safety experts around the world who were concerned with the dangerous cocktail that existed in buildings of a similar nature to Grenfell that existed within this building and many similar structures. This was not just an issue with combustible cladding, it was a combination of many failures.
The building industry needs a proactive approach to building codes and standards and a system (e.g. B-FLSR) aimed at improving the ageing building stock in all cities.
A flexible approach for evacuation designed to meet the hazard, an alternative means of escape and occupant evacuation lifts would provide evacuation options to all.
People should be able to work, reside, occupy and manage emergencies in both old and new, high-rise buildings in complete safety.
- Boyce, K, 2014, “Mixed ability evacuation – the challenges for design and management of high-rise buildings”, University of Ulster.