From Prescriptive Standards to Proportional Risk: A Critical Analysis of English Fire Safety Regulation

Every time a building is designed or occupied, a silent agreement is made between the people who build it, the people who live or work inside, and the government that oversees them. This agreement is about fire safety. For decades, the way this safety was ensured relied on a simple, rigid idea: follow the rules exactly as written. If a wall needed to be made of a specific material, or a door needed to be a certain width, the law said so, and that was the end of the discussion. This approach is known as prescriptive regulation. It is like a recipe where you must use exactly two cups of flour and bake for thirty minutes; if you do, the cake is safe. But fire is not a cake. It is a chaotic, unpredictable event that behaves differently in every building, depending on what is inside, how people move, and how the wind blows. In recent years, the rules have shifted away from strict recipes toward a more flexible idea called performance-based regulation. Instead of saying "use this material," the law now often says "ensure people can escape safely." This puts the burden on the designer or building owner to prove their building works, rather than just checking a box. The question that remains, however, is whether this flexibility is working, or if it has left too much room for confusion and error.

A team of researchers from the University of Liverpool set out to trace the history of these rules in England, looking at how the approach to fire safety has changed from the end of the Second World War to the present day. They did not just read the laws; they treated the legislation itself as a dataset. The team gathered twenty-one key pieces of law, ranging from old public health acts to the most recent Building Safety Act of 2022. They then carefully examined every single requirement within these documents, sorting each one into one of two categories. The first category was "rules-based," where the law demands a specific action or standard. The second was "performance-based," where the law sets a goal, such as limiting the spread of fire, and leaves the method of achieving that goal open. By counting and comparing these requirements across the decades, the researchers mapped the evolution of fire safety thinking. They found a clear, gradual shift. In the years immediately following the war, the laws were almost entirely rules-based, demanding specific materials and construction methods. Over time, particularly after the 1980s, the balance tipped toward performance-based goals. The law began to ask for outcomes rather than specific instructions, trusting that experts could find the best way to achieve safety.

However, the study revealed that this shift is not a smooth, straight line. The researchers discovered that major tragedies often interrupt this trend toward flexibility. When a large fire causes many deaths, the government tends to react by tightening the rules again, returning to a more rigid, prescriptive style. For example, after the fire at King's Cross underground station in 1987, new laws were passed that mandated specific standards for subway stations. Similarly, the devastating Grenfell Tower fire in 2017 led to new legislation that, while still rooted in performance-based ideas, introduced specific bans on certain materials and created new, strict roles for building managers. The researchers noted that while the overall direction of the law is toward risk-based thinking, these moments of crisis pull the system back toward certainty. This creates a hybrid system where the law asks for flexible outcomes but often provides rigid guidance on how to get there.

The core problem identified by the researchers is that this shift has created a gap in understanding, particularly for buildings that are already occupied. For new buildings, there are detailed guides that explain how to meet the safety goals. But for existing buildings, the law relies on a concept called "proportionality." This means that the safety measures taken should be appropriate to the risk, without being excessive. The researchers found that the law never actually defines what "proportionate" means. It is a word that changes depending on who is using it. A building owner might think a measure is too expensive to be proportionate, while a fire safety officer might think it is essential. Because there is no clear definition, the system relies heavily on the skill and judgment of the individuals involved. If a building manager is not fully trained, or if a regulator does not have the right data, the safety of the building can vary wildly. The study showed that in many cases, people are simply following old rules or guessing what is safe, rather than using actual data about how fires behave to make decisions.

The researchers also pointed out a critical lack of data to support these decisions. While there are guides for designing new buildings that use statistical data about fire frequency and growth, these guides often rely on information that is decades old. They do not reflect how modern buildings burn, or how new materials and technologies, like lithium-ion batteries, change the risk. Without up-to-date data, the "performance" of a building is often judged against a picture of the past, not the reality of the present. The study suggests that for the system to work, regulators and building owners need access to current, real-world data about fires. They need to know not just that a fire happened, but exactly how it started, how it spread, and which safety measures worked or failed. Only with this kind of information can the concept of "proportionality" be applied correctly, ensuring that every building has the right level of protection for the risks it actually faces.

Ultimately, the paper concludes that the move from strict rules to flexible goals was a necessary step, but it has not yet been fully realized. The system is currently stuck between two worlds: it asks for flexible, risk-based thinking but often provides rigid, outdated guidance to achieve it. The researchers argue that to fix this, the focus must shift from simply checking if a rule was followed to understanding the actual risk in a building. This requires a new approach where decisions are driven by real data and a clear understanding of what "safe enough" actually looks like for every specific building. Until the definition of proportionality is made clear and backed by solid evidence, the safety of the people inside these buildings will remain dependent on the variable skills of the people managing them, rather than on a system that is truly designed to keep them safe.