Self-extinguishing materials (including recycled) and advanced construction techniques for the fire protection of skyscrapers

Thermal insulation on skyscrapers not only improves the building's energy efficiency but plays a crucial role in fire protection by mitigating the chimney effect, under certain applicative and qualitative conditions of the insulators, which can accelerate the spread of flames.

Given the increasing height and complexity of modern urban structures, fire safety has become a top priority. This article explores how to construct an effective and safe thermal coat, with a particular focus on self-extinguishing materials and advanced construction techniques.

The Chimney Effect in Case of Fire in Skyscrapers

The chimney effect occurs when hot air rapidly rises within a building, creating an upward flow that draws in fresh air from lower openings. In skyscrapers, this phenomenon can dramatically accelerate the spread of fire, pushing it towards the upper floors at an alarming rate.

Insulating Materials and Fire Risk

But external insulating materials can also significantly contribute to the chimney effect if not adequately selected and applied. Highly flammable materials not only fuel the fire but can also generate toxic fumes, putting the safety of occupants at risk.

Self-Extinguishing Insulating Materials

Definition and Importance of Self-Extinguishing

An insulating material is considered self-extinguishing when it is capable of stopping the spread of flames without external intervention.

This characteristic is crucial in skyscrapers, where access to upper floors for extinguishing operations might be difficult. Self-extinguishing is measured through specific standards that assess a material's ability to extinguish within a defined time after ignition.

Overview of Common Insulating Materials and Their Reaction to Fire

Common insulating materials include polystyrene (EPS and XPS), polyurethane, rock wool, and fiberglass. Each presents unique characteristics in terms of fire resistance:

Polystyrene (EPS and XPS): While offering good thermal performance, it requires flame retardant additives to improve fire safety.

Polyurethane: Has excellent thermal resistance but can degrade quickly in the presence of fire if not treated properly.

Rock wool: Naturally fire-resistant, does not contribute to flame propagation and is often used in applications requiring high fire resistance.

Fiberglass: Similar to rock wool, offers good fire resistance performance.

Criteria for Choosing a Self-Extinguishing Thermal Insulator

When selecting a thermal insulator for skyscrapers, it is crucial to consider:

The fire reaction classification: Prefer materials classified as A1 or A2, according to European standards, indicating no or limited contribution to fire.

Density and thickness: Factors that influence the insulation capacity and fire resistance of the material.

Durability and chemical stability: The material's ability to maintain its properties over time, even under adverse conditions.

Thermal Insulators Made with Recycled Materials

Recently, attention has shifted towards sustainable insulating materials made with recycled materials, which not only offer good thermal resistance but are also more eco-friendly. Examples include:

Cellulose-based insulators: Made primarily from recycled paper, treated with boron to confer fire-retardant properties.

Recycled wool panels: Use fabric and wool scraps to create insulating panels with good fire resistance properties.

Recycled polystyrene: Although polystyrene is less desirable from a fire resistance standpoint, recycled versions treated with flame retardant additives can represent an economical and relatively safe option.

Best Thermal Insulators in Relation to Fire

We will now delve deeper into thermal insulators, focusing on their effectiveness in relation to fire, to identify the safest and most performant materials for use in skyscrapers.

Comparative Analysis of Insulating Materials

To understand which thermal insulator offers the best performance in case of fire, it is essential to consider several factors, including fire resistance, thermal insulation capacity, and emissions in case of combustion. Here's a brief overview:

Rock wool: Excels in fire resistance thanks to its mineral composition. It does not burn and is capable of withstanding temperatures above 1000°C. It also offers excellent thermal and acoustic insulation.

Fiberglass: Similar to rock wool in fire performance and thermal insulation, but may be less comfortable to handle due to the fine fibers that can irritate the skin and respiratory tract.

Treated polyurethane: With the addition of flame retardants, expanded polyurethane can achieve good fire resistance, but remains inferior to rock wool and fiberglass in terms of fire performance.

Polystyrene (EPS and XPS): Even if treated with flame retardants, they tend to perform less well in fire situations compared to the other materials mentioned.

Technical Data: Fire Reaction, Temperature Limits, Toxic Emissions

Selecting insulating materials for skyscrapers must take into account not only their thermal insulation capability but also their reaction to fire.

Materials like rock wool and fiberglass do not contribute to flame propagation and withstand extremely high temperatures without emitting toxic substances. In contrast, polymer-based materials, even if treated with flame retardants, can degrade and release toxic gases at high temperatures.

Toxic Emissions from Insulating Materials in Combustion of Toxic Fumes

When insulating materials burn, they can release a variety of toxic fumes and dangerous gases. The composition and quantity of these emissions vary depending on the type of material involved in the combustion. The fumes can include carbon monoxide (CO), dioxins, hydrochloric acid (HCl), hydrogen cyanide (HCN), as well as fine particulate matter that can carry toxic substances deeper into the respiratory system.

Composition of Fumes and Responsible Materials

Polystyrene (EPS and XPS): In case of fire, polystyrene can release carbon monoxide and benzene, an aromatic hydrocarbon known for its carcinogenic properties.

Polyurethane: The combustion of polyurethane can produce hydrogen cyanide, an extremely poisonous gas, in addition to carbon monoxide and carbon dioxide (CO2).

PVC and other chlorine-containing plastics: The combustion of insulators containing PVC can generate hydrochloric acid, dioxins, and furans, substances that are highly toxic and persistent in the environment.

Impacts on Human Health

Exposure to toxic fumes can have serious health consequences, including:

Irritations: Eyes, skin, and respiratory tracts can suffer acute irritations due to exposure to acidic gases like hydrochloric acid.

Carbon monoxide poisoning: Carbon monoxide, when inhaled in sufficient amounts, can be fatal as it prevents oxygen transport in the blood.

Long-term effects: Exposure to dioxins and other persistent organic compounds can have carcinogenic effects or damage the immune system over the long term.

Mitigation Measures

To reduce the risk associated with toxic emissions, it's essential to:

Choose materials with a low potential for toxic emission: Prefer insulating materials that, in case of fire, release fewer dangerous substances.

Smoke and gas evacuation systems: Implement safety systems designed to reduce the concentration of toxic fumes in indoor environments.

Rigorous standards and testing: Ensure that all insulating materials undergo rigorous testing to evaluate their behavior in case of fire and the potential for toxic emissions.

Fireproof Thermal Coat Construction Techniques

Designing and installing fireproof thermal coats requires careful attention and precision to ensure the building is effectively protected against fire spread.

Fireproof Design Principles

The fundamental principles in the design of fireproof thermal coats include:

Structural integrity: Ensure that insulating materials are applied in a way that does not compromise the building's structural integrity in case of fire.

Fire barriers: Installation of fire barriers at critical points to prevent the spread of flames through the thermal coat.

Ventilation: Design ventilation systems that prevent the chimney effect, limiting the amount of oxygen available to fuel a fire.

Application Methods and Integration with the Existing Structure

Applying fireproof thermal coats requires specific techniques to ensure they are well integrated with the existing structure:

Mechanical fixing: Use of fixing systems that do not compromise the fire resistance of insulating materials.

Fire-resistant sealants: Use of fire-resistant sealants and foams to close any opening or joint, preventing flame penetration.

Monitoring and maintenance: Implementation of a monitoring and maintenance program to ensure the thermal coat's integrity over time.

Fire Propagation and Technical Data

Understanding the mechanisms of fire propagation is essential for designing effective insulation systems. Fire can spread vertically through the chimney effect but also horizontally, through the thermal conduction of materials.

The choice of materials and construction techniques should be guided by solid technical data on how different materials react to heat and fire, as well as their thermal insulation properties.

Case Studies: Catastrophic Fires in Skyscrapers

We will take a closer look at some of the most significant skyscraper fires, examining the causes, dynamics of fire spread, and lessons learned in terms of fire safety and material selection.

Grenfell Tower, London, 2017

What happened: In the early hours of June 14, 2017, a fire that started in an apartment on the fourth floor of Grenfell Tower quickly spread throughout the building, resulting in 72 casualties.

Main cause: The rapid external spread of the fire was facilitated by the polyethylene (PE) cladding and polyurethane insulation panels, both highly flammable.

Lessons learned: The incident underscored the critical importance of using cladding and insulation materials that meet high fire resistance standards. It also highlighted the need for regulatory revisions and stricter controls on fire safety procedures in high-rise residential buildings.

Plasco Tower, Tehran, 2017

What happened: On January 19, 2017, a fire that broke out in the upper floors of the 17-story Plasco Tower led to the complete collapse of the structure, killing 22 firefighters.

Main cause: The lack of adequate fire safety measures and the presence of flammable materials inside the building contributed to the collapse.

Lessons learned: This disaster highlighted the importance of adequate fire prevention systems and buildings constructed to withstand prolonged exposure to fire, thus preventing catastrophic collapses.

Address Downtown Hotel, Dubai, 2015

What happened: On December 31 , 2015, a fire engulfed the Address Downtown Hotel in Dubai, causing significant damage to the building but fortunately resulting in no fatalities.

Main cause: Similar to the Grenfell Tower incident, the fire spread rapidly due to the material used for the building's exterior cladding, which included flammable components.

Lessons learned: The fire highlighted the need to review safety standards for cladding materials used in high-rise buildings, prompting Dubai to revise its building regulations to require materials with greater fire resistance.

Technical Literature

"Fire Safety in Buildings": This type of publication often explores regulations, materials, and design strategies to prevent and combat fires in structures of various sizes, potentially including skyscrapers.

"Materials for Sustainable Architecture: Performance, Sustainability, Recycling" by Valentina Serra: Although the focus is on sustainable architecture in general, the book may offer valuable information on innovative and sustainable insulating materials, some of which possess good fire-resistant properties.

"Building Systems Technology: Design and Construction": Books with this title tend to cover a wide spectrum of building technologies, including thermal insulation systems. They can provide useful technical information on the selection and application of insulating materials in skyscrapers.

"Civil and Environmental Engineering Handbook": Although not focused exclusively on thermal insulation or fire safety, such a comprehensive handbook may contain chapters or sections dedicated to fireproof design and insulating materials used in construction.

The challenges of ensuring fire safety in skyscrapers are complex, involving the careful selection of materials, adherence to rigorous standards, and the implementation of advanced design and construction techniques. By learning from past incidents and leveraging the latest in fire-resistant technology and materials, the construction industry can better protect these towering structures and their occupants from the devastating impact of fires.