22 AUG 2016
“Super stroked to showcase, the 325 bedded Venkateshwar super speciality hospital …” read the Facebook post of Dipankar Mazumdar, an architect incredibly talented and insanely nice to hang out with.
A picture of the building with its surrounding was attached and the post threw some more words across-
‘The operations having been started just few days back… the hospital building was a much needed medical facility in sub city of Dwarka (Delhi-SW)”, it blissfully ended with a congratulatory note to “all those who were involved in planning design and execution of the project”.
We all do this as professionals. Share our feelings for our project
- Proud -when objective is met.
- Happy -when we have bigger budgets, cheaper materials, braver clients, elastic building regulations, professional team and tolerant neighbours.
- Contend-when buildings stand the test of time.
Totally wrapped in these thought I entered the TAJ hotel conference room, to attend a panel discussion on-“An architect’s decisions affect public safety”
On the screen was a building on fire. One could see smoke billowing from below, and people stuck on top floor.
On the stage were seated some 4 panellists around a small coffee table and I could see the introductions almost over by the moderator- Mr. Lalit Pandey; who as I know is a leading consultant of façade engineering for more than two decades now. A man with background in engineering, and experience of working over several facades.
A young architect in the front row was giving the meaning of façade perhaps as he understood-to some 80 odd architects seated in the hall in rapt attention
A façade is a simple self-supporting structure that handles its own weight, through a system of-
- Brackets that provide fixity
- A Grid which is usually a metallic structure spaced to withstand forces
- Skin –held by the grid usually covers the building – it could be glass, Aluminium composite panels or a host of other materials in much smaller measures.
Façade protects against-Weather, Noise, pollution, withstand earthquake and resist winds; perhaps with a pleasing look
Mr. Pandey to be referred as moderator from now on smiled down and asked –“WHERE did the process of thinking: overlook the fire requirement?”
That’s what the panellist had collected for, he added -to offer unbiased opinion on all aspects of fire safety independent of any manufacturer, supplier or installer.
The slide had changed and I had finally with organizer’s help located my reserved seat in the front row next to a known face. Seated comfortably, I could clearly see Panellist A picking momentum to start the session –
How should a building approach be towards fire?
He emphasised it is important that the difference between ‘reaction-to-fire’ and ‘fire resistance’ is cleared to understand the subject thoroughly.
Reaction-to-fire mainly deals with Classifying material on basis of –
- if they burn (combustibility);
- how easily they burn (ignitability and flame spread)
- What happens when they burn (smoke development and resulting toxicity).
Architects all over use material classification to ensure the right material is in the right place with the aim of preventing a fire from starting, or limiting its spread. I could instantly relate this to the brick column structure of the hospital building in the FB post where Kalzip façade system was used.
whereas, Fire resistance, mainly addresses building systems (such as walls, floors, ceilings, and doors) and their compartmentation abilities.
_ The FB post once again ran through my mind and I knew for instance, that the 20mm thick block work used there is fire rated for two hours as per NBC. As Fire resistance is always measured in terms of ‘time’ the rating would help to know how much time is there to enable patients and people to get out in time, as well as limiting damage to property.
Back on the stage Panellist B continued the discussion – at times where compartmentation is required in fire safety strategy, the gap between the façade and the building (typically at the floors), must be sealed to limit fire spread. This is called ‘perimeter fire stopping’ in architectural jargon. To confine a fire to the zone of origin, for a specified time, thereby preventing fire spread and leaving more time for safe evacuation of the building occupants.
For example as shown in the below slide-; A vertical fire spreading can be broken by perimeter systems that seal the gap between the floor slab and the façade.
Ooh..so this building mentioned in the FB post has brick structure and therefore does not require this perimetre fire stopping, went my crazy mind. O-yeah wemaweh!!- this was becoming more and more crystal clear that buildings with glass, aluminium and steel require it.
In the audience someone almost thought the same coz I heard this question put up – Architects have been using a common façade material ACP or aluminium composite panel for many years now but is it fire resistant?
Panellist B by now had everyone’s attention, and like a college professor he answered,
Non-fire rated or budgetary versions of ACP often comprise a 2-5mm core of low density polyethylene (LDPE) sandwiched between two layers of aluminium (generally 0.5mm thick on each side).
If a fire test is performed all would know polyethylene catches fire but as a composite material, the fire has to go through the two external layers of aluminium before it can ignite the inside core. It will not be able to penetrate the skin and therefore never reach inside –as the slide showed
But perhaps that will not be the scenario in a real life building fire. He sighed!!
True -spoke my head”… in a real building scenario vertical fire will reach in between the panel.”
If test don’t give us real information about such an important safety factor what does-?!I heard an exasperated audience ask
– The answer to this is a more aggressive fire test.- Panelist C answered a tad bit loud perhaps totally excited at this turn of discussion. All focus was on him now.
He continued, -full-scale mock-ups can be staged with the wall system containing the material fixed to a test wall two storeys high. NFPA 285 or BS 8414 are two such tests that can be done.
In these test, a fully developed fire is simulated by two ways
- adjacent to the end wall, thinking it spreads from neighboring building(an outside fire reaching the mock up building)
- or-it can be staged breaking out from a window.(fire from inside spreading out in the mock up building)
The heat release from these tests is sufficient to properly test the façade and evaluate its performance in spread-of-fire terms.
This ignited more questions from the audience.
Hands were shooting up and the race had started as to who would fire their question first-
Question 1-what happens when the glass of the façade breaks or the aluminium melts?
A common solution- spoke the Panellist D is the selection of more durable materials that are not going to break or melt once the fire starts such as fire rated glass or steel framing or durable panelling.
Question2– What if the fire starts in an adjacent building?
If two buildings are abutted, in that case answered Panellist D, that the resilience of the adjoining building must be part of design.
It was almost an hour and a half of knowledge sharing and questionnaire round.By now, the moderator was wrapping the discussion. The overall summary went like-
Fundamental principles of fire control are prevention and containment.
- Materials should be selected to minimise the chance of a fire developing.
- Systems should be designed so that if a fire does develop, it can be contained to the greatest extent possible.
- Containment is intended to provide occupants with enough time to escape, limit fire spread and minimise damage.
Tea break was announced and all were requested to come back in half an hour for the next panel discussion.