Smoke Permeability Standards Make Hospitals Safer

3-7-2020

Smoke is faster and deadlier than fire. Moreover, it behaves differently. Yet the standard for smoke resistance in the current Dutch legislation is deduced from that for fire resistance. The new legislation uses realistic, testable standards for smoke permeability according to the European standard EN 1634-3. However, until now, most hospital architects have not been concerned with the new requirements for smoke permeability. And that is a shame, according to experts. Because it would make hospitals much safer.

What many people do not know: even briefly inhaling smoke can be deadly. Three reasons why it is dubbed the silent killer by fire fighters;

Small soot particles can cause infections in the trachea and lungs;
Smoke contains the toxic gases carbon monoxide and cyanide that eliminate oxygen supply to the brain, kidneys and intestines when inhaled, as well as cell metabolism;
The hot air sears the mouth, throat, vocal chords and lung alveoli.

"Life threatening," said prof. dr Breederveld, Professor of Acute Burn Medicine and trauma surgeon at the burn centre Beverwijk during a campaign about smoke. "Even in case of brief exposure. I still see survivors of a fire die en route to our hospital due to smoke inhalation." Where fire safety is concerned, smoke poses a fourth danger that is often forgotten, says Maarten de Groot, fire safety expert at Altavilla. "Smoke inhibits visibility, a crucial factor in evacuating a building." According to, De Groot health institutions such as hospitals have plenty of attention for fire safety, but all too often underestimate the dangers of smoke. "Hospitals hold regular fire drills to test and practise an evacuation. But these are always dry runs, without smoke development. While smoke inhibits visibility and breathing, panic ensues and it significantly reduces the time available for evacuation. Moreover, smoke can cause substantial material damage to hospitals."

Arbitrary Principle

The smoke resistance standard of smoke or sub-fire compartments is currently linked to the fire resistance as intended in the EN 1643-1. Maarten de Groot clarifies: "The level of smoke resistance of a structural element, such as a wall or door, is now denoted with a time indication. This is based on the tested fire resistance multiplied by one and a half. Completely arbitrary, if you ask me." And that is something all experts agree on. A fire-resistant partition could let in a lot of smoke, Efectics - one of the two parties in the Netherlands that has the official authority to test the smoke resistance of products - reports in a presentation. Making a fire-resistance structural element (such as a wall or door) airtight to slow down the fire is usually done by means of 'active sealing agents' in cracks and seams. Marcel Schoppers, from Metaflex Doors, one of Europe's largest suppliers of medical door systems, explains: "Our smoke and fire-resistant doors are always sealed airtight with rubber sealing profiles. In high temperatures, these will melt, but in the fire-resistant doors, special Interdens strips are activated that start foaming at approximately 100 degrees Celsius to provide an airtight seal for cracks and seams. However, regular fire-resistant partitions and doors only have the swelling strips and that let smoke through in lower temperatures."

More Attention for Smoke Containment

The current policy falsely assumes that a fire-resistant partition will contain smoke 1.5 times longer than it contains fire. Therefore, it was announced in 2016 that the new legislation will set requirements for hot and cold smoke resistance, as intended in EN 1634-3, measured by means of the smoke or air permeability: leakage. Structural elements such as doors including frames must be tested according to the regulations, as stipulated by the Sa and the S200 standard.

De Groot clarifies the standards: "S200 is a boundary value for partition structures with a smoke-resistant function. The boundary value concerns the tightness for smoke with a temperature below 200 degrees Celsius, measured under a specific pressure. The boundary value is applicable to partitions of sleeping quarters, for instance. That is a 'protected sub-fire compartment', such as spaces where children sleep. The S200 standard will apply to other partitions between protected sub-fire compartments as of July 1^st 2021. In case of a hospital, the doors of patients, IC or staff with sleeping function must always meet the S200 standard. The boundary value Sa applies to other partition structures with a smoke-resistant function, the boundary value for leakage of 'cold' smoke".

Safer and less damage

Experts say that attention to smoke permeability substantially increases the safety of buildings and can even reduce the costs for new developments and renovations. Schoppers: "Our smoke-resistant doors are airtight with rubber profiles with double sealing, have been tested in terms of smoke permeability and meet the S200 or the Sa standard."

Besides, insurers are often very concerned with preventing smoke damage as it is usually more expensive than fire damage, Schoppers notes. "Due to all the fire safety provisions, such as automatic sprinkler systems etc., fire damage is often limited. Smoke and soot particles, however, spread much more quickly and easily and therefore cause much more damage to people, materials and the building. I would not be surprised to see that insurers will increasingly aim their coverage conditions more towards smoke resistance."

Look Beyond the Standard with a Fire Safety Concept

Nothing but advantages so far and yet hospital architects still often use the old standards. That is understandable, as permits for renovation and new development are granted for plans that meet the old legislation. However, De Groot and Schoppers believe that hospital architects and their project teams should follow the smoke-permeability standards. They do have one important comment, though:

Schoppers: "When an architect presents his design and plan to us, we provide a logistical door plan that gives advice per passage - based on the wishes and the upcoming legislation and regulations - about the various options. We feel that those that meet the more stringent legislation, also meet the old legislation in terms of safety, if properly calculated and reasoned. Ideally, the architect and client subsequently consult with their fire safety expert. That is always our recommendation. We know everything about our doors, the spaces of our clients and the requirements. And naturally, we closely follow developments in legislation and regulations. But we cannot take over the position of a fire safety specialist; he has the know-how to oversee an entire project in terms of fire safety."

De Groot adds: "In case of fire and smoke resistance, you should never approach one structural element, such as a door, as a stand-alone part. We should not take the legislation and regulations as starting point, but as minimal legal lower limit. Instead, we should inventory and analyse the risks and based on that make a fire safety concept that answers the preset fire safety goals. In doing so, we look at the design as a whole, the use of spaces, at the people in specific situations in these spaces, escape routes, the potential speed of smoke dispersion and the role of the doors in that design et cetera. In doing so, the size of the smoke compartments must be in line with the available evacuation capacity of the internal emergency response organisation. You can have the best smoke-resistant partitions in the world, but if the evacuation area behind it is larger than what the emergency response organisation can handle, the smoke will still cause victims. When looking at the design from this perspective, i.e. with an eye for safety, you will eventually always easily meet the standard in my experience."

Should you immediately fear for your budget when reading these words: a fire safety concept also includes a feasibility study that evaluates the desired measures to get a good idea of the safety level, matching the use of the spaces and fitting the budget. A fire safety concept ensures that you will have a maximally effective fire safety plan, at the most attractive investment.

Start on time. So, start at the beginning.

This investment is much higher when fire safety is not included until halfway through the process. De Groot: "When designs are already in their final stages, adjustments are unnecessarily expensive and partitions between fire and smoke compartments must often be placed in inconvenient locations." What is the right moment? The project definition. "In that case, fire safety can be included in the specification of requirements and perfectly integrated into the design. Ideally, the expert participates in the occasional meeting with the design team after the project definition, to keep a close eye on the process and contribute alternatives," according to De Groot. "This benefits the building's functionality, the budget and the aesthetics: central principles in every construction project."

Curious about the possibilities and what Metaflex can do for you and your hospital? We are happy to inform you!

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