Atriums are now the central feature of buildings. The bigger the atrium, the better the ‘wow’ factor. However in case of a fire, all the elements that were striking features of the atrium – glass, lighting fixtures, advertising props – can take on a dangerous turn and become elements of mass destruction.
As per the National Fire Protection Association (NFPA) codes and standards, sprinklers are to be provided throughout the building unless there is a provision in the Standard that indicates otherwise. In addition, a deluge system (for a small atrium) or more than one (for larger) or a precaution system should be included in the building plan. These systems should be controlled by smoke detectors on the ceiling. However the codes also state that closely spaced sprinklers and draft stops are not required around large openings such as those found in atrium buildings, and similar structures where all adjoining levels and spaces are protected by automatic sprinklers.
However, there are several big technical issues that must be considered while installing fire sprinklers in atria. There has to be very good air circulation and ventilation at the top of the atrium without which the ambient temperature may be elevated and would need intermediate temperature rated heads (which will impact system response times). Second, it is possible for the smoke from the combustibles to stratify below the sprinklers (cold smoke phenomenon) or be removed by the HVAC system (or smoke removal system) before reaching the sprinkler heads. Additionally, a deluge system tied to beam type smoke detectors and flame detectors located below the stratification height would be an ideal option.
Third, the geometry of the atrium (such as a peaked or barrel roof) might divert the hot smoke away from point of origin such that the sprinklers may go off over a clear portion of the floor space and miss the point of origin. The fourth big technical issue with atria is the possibility of the smoke plume being so hot and dense that it vaporizes the water droplets before they reach the fire. In such a scenario, since the water is not reaching the fire, it cannot vaporize there and remove heat from the fire itself and there is no steam present to help smother the fire. Considering all these, it would be necessary to use large drop sprinkler heads or increase the discharge density or both.
Atriums, regardless of the number of floors involved, must be separated by a 1-hour fire barrier. This isn’t as restrictive as it first appears, since it is much better than the 2-hour enclosure required of vertical shafts connecting four or more stories. The code permits the use of sprinklers at six-feet on centre along glazed openings in lieu of the 1-hour rating. The sprinklers need to be only on the room side if no walkway is provided on the atrium side of the separation. For those wanting glass openings into the atrium, this would be a cost-effective alternative to fire-rated glazing since a sprinkler system is already mandatory.
The use of fast optical detectors (that detect the fire while it’s small preferably at it’s ignition point) coupled with automatic sprinklers and smoke detection in such large areas, may be the best solution. The alarm issued by the fast response optical detectors can alert the first responders and fire brigade in time to address areas that are not covered by sprinklers.
Exit ways or stairways are usually non-descriptive doors hidden in barely accessible areas of a structure. Exit ways in hospitals or commercial establishments have stickers stuck on them to indicate their existence, however such is not the case in most residential areas. In the recent past there have also been instances of the doors to exit ways being blocked or modified to suit the changed décor! An important point to ponder on is the need for protective coating on such exit doors and if glass doors can be used.
An exit door can be a door directly to the outside at ground level, such as the front door to a building. In that case, unless there is an unusual exposure hazard, the door requires no fire protection rating and therefore can be of any glass acceptable to the building code for impact resistance. In fact there might only be a hole in the wall with no door leaf at all in climates where this is acceptable. There is no restriction on the material an exit door is made of, as long as it meets all the other requirements of the code. Fire-proof glass doors offer relatively higher protection from fire hazards than conventionally used material. The additional benefit of using glass for exit doors is that glass provides visual security and also enables one to see through in case of fire accidents and detect fire very early.
If it does require a fire protection rating, then there are numerous glazing options for virtually every type of exit door. There are selections of fire resistance rated glazings that meet all the requirements of NFPA.
Companies like Saint-Gobain have a rage of state-of-the-art fire resistant, fully glazed doors in India. In terms of fire safe non-glass doors, various options are available in the market, however it is important to can be procured from companies like Godrej & Boyce Mfg Co Ltd, Radiant Safedoors Pvt. Ltd among others.
Incorporating fire resistant glass and fire proof systems, automatic sensors and high pressure water sprinklers into their designs should be the very first preventive measure that architects and interior designers need to take towards making a building safe and secure.