The calorific value of a building material is an important indicator for assessing its behaviour in the event of fire. It describes the amount of energy released during the complete combustion of a material – such as a façade panel. This value is expressed as the PCS value (Pouvoir Calorifique Supérieur).
In general: The lower the PCS value, the lower the energy contribution of a material to a fire event.
The importance of calorific value for fire performance
In building science, the calorific value plays a critical role in fire risk assessment. Materials with a high calorific value release large amounts of energy, which can significantly intensify and accelerate the spread of fire. In contrast, materials with a low calorific value release much less energy and contribute significantly less to fire development. These materials can help slow down fire spread, reduce the risk of uncontrolled fire propagation and ultimately enhance building safety.
Relevance for façade systems
In façade engineering, the calorific value is a key criterion for selecting suitable materials. Especially non-combustible materials classified as A1 or A2 according to the European standard exhibit very low calorific values. In the event of fire, they release only minimal amounts of energy, thus significantly reducing the risk of façade fires.
Façade elements influencing fire behaviour
The fire performance of a façade results from the interaction of all installed components. To ensure a high level of fire safety, it is essential to use non-combustible or fire-retardant materials with low calorific values. Careful material selection during the planning phase is crucial to improving the overall fire safety of a building.
Key components of ventilated façade systems with an impact on fire safety:
- Façade cladding
As the outermost layer, the cladding significantly affects a building’s fire behaviour. Materials rated A1 or A2 offer the highest level of protection, as they are either non-combustible or release only very low amounts of energy.
- Insulation materials
The choice of insulation also plays a vital role in fire protection. Ideally, non-combustible or fire-retardant materials with low calorific value should be used to limit fire spread within the façade system.
- Air gaps and cavities
Ventilated façades often include air layers for natural ventilation. These areas must be designed to prevent uncontrolled fire propagation. Thoughtful planning can stop airflow from intensifying a fire.
- Adhesives and fixings
Connectors such as adhesives, screws or anchors also influence fire performance. They should be made of fire-resistant materials and be suitable for use in safety-critical façade systems.
Example of a safe façade solution – ALPOLICTM NC/A1 + Mineral Wool
A particularly safe façade solution results from the combination of ALPOLICTM NC/A1 with non-combustible mineral wool insulation. This configuration achieves a total calorific value of just 15 MJ/m² (8 MJ/m² for the panel, 7 MJ/m² for the insulation) – one of the lowest values currently available on the market. The extremely low heat release significantly reduces the energy emitted during a fire, helping to maximise building safety.
Comparison of calorific values of different façade claddings
The overview shows the calorific values of different façade materials, all measured with identical test methods. And you can see immediately that ALPOLICTM NC/A1 has by far the lowest calorific value:
