Fire safety is a fundamental consideration in building design, requiring careful planning to protect both the structure and the people within it. A key part of this protection involves selecting appropriate materials, especially insulation—which plays a vital role in limiting the spread and impact of fire. This is particularly important for HVAC systems and ductwork that run throughout the building. Choosing the right insulation can mean the difference between containing a fire and allowing it to spread.
Fire resistance focuses on containment, helping to prevent flames and smoke from moving through a building, while fire protection ensures that critical components, such as structural supports, remain operational during a fire.
This article explores the key factors to consider when selecting insulation to support overall fire safety.
Fire safety is the overall goal to safeguard against fire. Building standards are closely related to this. Fire protection specifically is what you do to make a building safe from fire. Fire protection measures should:
There are two key types of fire protection - passive fire protection (PFP) and active fire protection (AFP).
Active fire protection: Consists of fire protection systems that require aither automatic or manual activation or operatio, in order to detect, control, suppress, or mitigate fire or smoke. Some active solution examples are sensors, alarms, and sprinklers.
Passive fire protection: Measures include structures, layouts, systems and applications which naturally limit fire ignition or spread. PFP is crucial to fire safety and typically forms part of any building’s fire safety design. It focuses on containing and slowing the spread of fire and smoke.
Compartmentation design divides the building into smaller zones. Each compartment has fire-resistant materials to create barriers that prevent fire from spreading to other parts of the building. However, there are areas that need particular attention and may require specialist fire-rated components, including doors, windows, ventilation ductwork and services that pass through compartment walls and floors.
Understanding fire to better control it
For effective fire protection, it is important to understand the life and behavior of fire, to limit life and minimize its effects. Fire needs three things – oxygen, heat and fuel.
By limiting any element of the fire triangle (heat, fuel and oxygen) the fire can be contained more easily, protecting the building and everyone in it. When all these three things are abundant, fire tends to follow a pattern - ignition, growth, fully developed and finally decay.
The aim of fire protection is to prevent fire from growing and becoming fully developed. At this stage, it creates the most damage and poses the highest risk to structural integrity and overall safety. Therefore, it is important to understand that gases released in the early stages of a fire can become fuel for a growing fire.
Even with fire compartmentation and fire zones, it is crucial to limit the fuel, heat and oxygen. Choosing fire-resistant properties will help reduce the fuel available. In HVAC systems, fire-resistant ductwork and insulation can help maintain fire compartmentation and prevent feeding the fire with extra fuel.
As the chart above shows, choosing materials that can resist fire at all stages is important.
To raise safety levels, all construction products, materials and building elements are classified by their reaction to fire using the Euroclass fire rating under standard EN 13501-1 which categorizes materials into different classes, from A1 to F, based on their fire behavior. The Euroclass System only addresses reaction to fire (combustibility, smoke and flaming droplets)
Reaction to fire
The ‘Reaction to Fire’ testing measures a material’s contribution to fire. For classes A2, B, C and D, Fire Growth Rate (figra) assesses heat contribution and Smoke Growth Rate (SMOGRA) assesses smoke production. Different materials have different testing standards for the Euroclass Fire Safety classification.
Euroclass includes seven ratings. Stone wool is a non-combustible insulation material that meets the highest fire classification for building materials, A1, according to EN 13501-1. This means that it does not contribute to fire development or spread and does not produce significant amounts of smoke or flaming droplets. Stone wool has a high melting point of over 1,000 °C*.
*Internal test method
A1 | Non-combustible materials. |
A2 | Limited combustibility/non-combustible (depending on local legislation). |
B | Combustible materials. Very limited contribution to fire. |
C | Combustible materials. Limited contribution to fire. |
D | Combustible materials. Medium contribution to fire. |
E | Combustible materials. High contribution to fire. |
F | Combustible materials. Easily flammable. |
For ratings A2-D, an additional class for smoke (s) and burning droplets (d) is also specified:
· s1: low smoke production
· s3: high smoke production
· d1: no droplets
· d3: high number of droplets
An example product classification would be: A2-s1,d0
The EN 13501-2 assesses fire resistance which provides performance over time under fire exposure. The core criteria are:
R (Load-bearing capacity): how long it supports weight during a fire
E (Integrity): The ability to prevent the passage of fire and hot gases into unaffected areas.
I (Insulation): The capacity to prevent temperature increases on sides not directly exposed to fire.
This is the REI classification. In addition to the core criteria, there are optional ones for more specialized performance, for example:
S (Smoke): Airtightness and the prevention of smoke affecting other areas.
For the full list, refer to EN 13501-2.
During testing, thermocouples (thermoelectric devices which measure temperature) are placed on specific areas according to the product’s appropriate testing standard. For example, ventilation and air-conditioning ducts are tested using EN 1366-1 and classified according to EN 13501-3.
No thermocouple should rise by more than 180 degrees Celsius above ambient temperature. And the average of four specific thermocouples must not rise above 140 degrees Celsius.
Products receive an EIS rating with a safe duration. For example, a product with an EI 30 rating did not exceed 180 degrees during testing and maintained an average lower than 140 degrees and maintained integrity for at least 30 minutes. EI 60 for 60 minutes, EI 120 for 120 minutes.
EN 1336-1 standard
Resistance to fire testing according to standard EN 1366-1. Capacity of the product to prevent the passage of fire and hot gases into an area not affacted by fire.
The examples shows the capacity of the product to prevent the passage of fire and hot gases into an area not affected by fire.
Testing done according to two scenarios:
• A External Fire (o->i; channel A)
• B Internal Fire (i->o; channel B)
Horizontal (ho) and Vertical (ve) directions.
All types of standard fire-rated walls and floors: plasterboard, masonry, lightweight (aerated) and heavy(solid, cast) concrete.
Four fire tests required for a complete fire rating -Example EI 60 (ve ho i <->o) S
As these classifications show, insulation plays a vital role in limiting the effects of fire. Fire-resistant insulation not only helps to comply with fire safety regulations but also aids fire resilience by creating an effective thermal barrier. Choosing insulation with passive fire protection qualities will further boost fire safety.
By protecting and maintaining fire compartments and limiting the spread of fire by minimizing heat penetration, people have more time to evacuate. It also provides firefighters with greater opportunity to control and extinguish the fire, preventing widespread damage to the building, and limiting major renovation or repairs.
HVAC ducts present a unique fire safety challenge. They must run through walls, floors and partitions to function. Therefore, they require careful consideration within fire safety and fire compartmentation plans. Inadequate insulation or structurally vulnerable HVAC systems could limit the effectiveness of fire protection measures in other parts of the building.
By using proper seals and fire-resistant materials, HVAC ducts can support fire safety by creating further barriers or compartments. Insulation that has a low reaction to fire will limit temperature increases and the spread of smoke, flames or hot gases to other areas of the buildings.
That is why proper fire protection for HVAC systems is critical. And why Owens Corning® PAROC® has developed the portfolio of passive fire protecion solutions under the name of PAROC® Vect. With the PAROC® Vect assortment, we are addressing the challenges that ventilation systems pose to fire safety. Our passive fire protection solutions for HVAC ventilation systems stand the test of time, protecting precious life.
We have specifically designed the PAROC® Vect passive fire protection insulation solution for ventilation systems, to slow down the spread of fire from both inside and outside the ductwork. The non-combustible PAROC® Stonewool insulation material does not burn, contribute to fire spread or produce smoke, helping to safeguard escape routes.
We have engineered PAROC® Vect insulation for passive fire protection and to meet the highest standards of fire resistance. When combined with other fire protection methods, our HVAC non-combustible products can help you design and maintain buildings with improved fire resilience, which are safer for everyone.
