Smoke and Heat Control Systems Deliver Essential Fire Safety

Smoke and Heat Control (SHC) systems are crucial to protect life in case of emergency but also to minimizing property damage and supporting business continuity. There is a general focus on fire suppression systems and often SHC designs are the silent hero working in the background, keeping environments safe during a fire event. 

A critical point to understand is that the majority of fire-related casualties are not caused by flames, but by smoke. Smoke inhalation, toxic gases and reduced visibility are the primary threats to occupants. Limiting or controlling the spread can significantly reduce casualties. This can be achieved through passive fire protection measures, but also through active solutions such as smoke and heat control systems, which manage smoke movement and accumulation during a fire.

SHC systems are not standalone solutions; they must be carefully integrated with other fire protection systems to function effectively. These include fire detection systems, where smoke detectors serve as the initial trigger for activating smoke control measures, and fire alarm systems, which coordinate occupant notification and emergency response. This system also works in tandem with sprinkler systems, which suppress fire while the SHC manages the resulting smoke and heat. 

However, the interaction between sprinklers and SHC systems requires careful consideration. Sprinkler activation relies on sufficient heat accumulation at the ceiling level to rupture the glass bulb of the sprinkler head. Since the primary function of an SHC system is to remove heat and smoke from the building, premature activation could delay sprinkler operation. For this reason, SHC activation should generally be postponed, allowing sprinklers to operate first.

Why SHC?

• Life Safety: The number one priority in any fire protection strategy is life safety. Smoke is responsible for more fire-related deaths than flames or heat.  For the year ending March 2025, 34% of fire‑related fatalities were due to being ‘overcome by gas or smoke’. SHC systems are designed to control the movement of smoke, providing tenable conditions for occupants to escape and for emergency responders to operate safely. These systems limit visibility loss, toxic fume exposure, and the buildup of lethal heat.
• Limiting Heat Exposure to the Building: High temperatures during a fire can damage structural elements and critical building infrastructure. Structural steel starts losing mechanical strength as temperatures rise from roughly 300‑400 °C, steel begins to weaken, and by around 550 °C. By managing heat and smoke stratification, SHC systems reduce the thermal load on the building. This not only helps preserve structural integrity but also limits fire spread, supports suppression efforts, and reduces the risk of structural collapse during firefighting operations, thereby improving firefighter safety when operating inside the building.
• Business Continuity: Fires can shut down operations for weeks or months, even when the actual fire damage is limited. Smoke infiltration, system contamination, and water damage from sprinklers can all contribute to extended downtime. A well-designed SHC system helps localise the damage, reducing recovery time and financial losses.
• Environmental Effects: Fires release toxic gases and particulate matter into the environment. Effective SHC limits the release of contaminants into occupied spaces and the atmosphere, contributing to a safer indoor environment and reducing overall environmental impact. Belgian fire prevention laws often mention “protection of property and persons.”

Design Principles of SHC Systems

• Pressure-Driven Systems: At the heart of many SHC strategies is the concept of pressure differentials. During a fire, the increase in temperature within the fire compartment naturally creates overpressure due to thermal expansion of gases. To keep evacuation paths free of smoke, escape routes such as stairwells and corridors can be pressurised, or the fire zone can be maintained at a relative underpressure through mechanical smoke extraction. Both approaches aim to control smoke movement away from critical egress paths. The national standards for smoke & heat evacuation (SHEV, NBN S21‑208) primarily address forced smoke extraction in large spaces. These standards often focus on mechanical exhaust ventilation rather than detailed pressure differential calculations for smaller buildings or escape routes. NBN S21-208-1 is mainly applied to SHC systems in large open spaces and addresses the use of smoke reservoirs. To form an effective smoke reservoir, sufficient building height is required so that smoke can accumulate above a defined smoke layer while maintaining a smoke-free zone beneath it to support safe evacuation. The standard covers both natural and mechanical ventilation approaches. External factors such as wind pressure must also be considered, particularly in exposed or windy locations, as wind can create overpressure conditions that reduce or even prevent effective smoke extraction.
• Natural vs. Mechanical Ventilation: SHC systems can operate through natural ventilation such as vents and windows that open to release smoke or mechanical systems such as fans and ducts that force air movement. Natural systems are generally simpler and energy-efficient, relying on the buoyancy effect of hot smoke. Whereas the benefit of using mechanical systems offer greater control, especially in large or complex buildings.
• Fresh Air Supply: Smoke control relies on extracting the smoke, but it also requires replacing air to prevent negative pressure. It also ensures systems function as designed. The location, cleanliness, and temperature of this fresh air supply are all critical to effective smoke management. Fresh air supply is often overlooked during design, but in practice, a 1:1 ratio is commonly applied between the aerodynamic area of make-up air openings and natural smoke extraction vents. Adjusting this ratio can influence the achievable smoke-free height and the size of the smoke reservoir, allowing optimisation of system performance for specific building conditions.
• Integration with Passive Fire Protection: SHC systems are significantly more effective when integrated with passive fire protection measures. Elements such as fire-rated walls and floors play a crucial role in containing fire and smoke within defined compartments, preventing their spread to other parts of the building. 

In addition, smoke curtains can be used to guide smoke toward extraction points or to limit its movement into escape routes and critical areas. This integration enhances the performance of the SHC system and also introduces redundancy, ensuring that even if one system underperforms, the other provides a vital layer of protection.

Regulations are legal requirements enforced by authorities, such as building codes, while standards like NFPA 92, ISO 21927, and EN 12101 are expert-developed best practices. Although standards may be referenced by regulations, they can also be voluntarily adopted to achieve higher safety levels. Designers must comply with local regulations but are encouraged to exceed minimum requirements by following well-recognised international standards.

Whether you're a designer, facility manager, or fire safety consultant, understanding and investing in high-quality SHC solutions is far more than a regulatory checkbox, it’s a critical step toward creating safer, more resilient buildings.

At Jensen Hughes, we support clients from the earliest design stages, helping develop tailored SHC strategies that not only meet Belgian regulatory requirements but also reflect best practices and real-world performance. SHC is never a one-size-fits-all solution; each building requires a case-by-case approach that considers its unique geometry, usage, and risk profile. With proper SHC systems in place, you're giving people the time and conditions to escape safely during a fire and helping emergency responders do their job more effectively.