In our modern society, we expect safety in the things we use, the activities we do, the places we go, and the buildings we occupy.

This is perfectly reasonable; in fact, we should not expect anything less than safety.

But what level of safety should we expect? No deaths, no injuries, no harm – 100 per cent safe?

Most people do not often take time to probe deep into these philosophical questions. But when we set policies and develop building regulations, these are questions that we must ask and answer.

In Australia, as in other countries, we are required by our regulations to design buildings to be fire safe. The objective is stated in our Building Code: “to safeguard people from illness and injury.” But what does it mean? Must we design buildings such that absolutely no harm is to come to any occupant in building fires?

Irrespective of how you might wish to answer the question, from a design viewpoint, the answer must sadly be no. This is not because we wish not do so, but because it is impossible to do so. Absolute safety is an unreachable target.

To ensure as much would require limitless knowledge and infinite foresight of what might go wrong. This includes the performance of the buildings, their systems, the behaviours and activities of their occupants…the list goes on. The most significant factor governing fire safety is occupant behaviour which, ironically, is beyond the control of building design; and sometimes makes safety design somewhat oxymoronic.

This does not mean that we cannot design safe buildings; just that safety is relative rather than absolute. We cannot predict all possible events that could happen. But we can design a building to have greater propensity to deal with fire events to offer a safer environment. Unfortunately, accidents – along with their unpredictable consequences – can still happen. That is Murphy’s Law.

You might argue that we just have to crank the design lever harder to control everything and all activities. After all, various safety professions have proclaimed that “all accidents can be prevented.” If that were the case, it follows that all injuries can likewise be avoided, and abracadabra, safety is absolute.

This sounds all well and good. Unfortunately, the proclamation mirrors more of an aspiration rather than a practical possibility. It serves as a useful and fruitful safety campaign slogan. It spurs us on to take greater care in things we do to prevent careless mistakes. But on the flip side, it lulls us into a false belief that we can reach an impossible goal. It allows the delusion to seep in our psyche that we can fully control everything around us, that we are the masters of the universe, we can reach the stars, nothing is impossible, including absolute safety.

But when we return to earth from the aspirational heights, we have no choice but to accept the reality that such a goal is impossible. This is not a cop-out nor a concession to defeat, but rather a pragmatic outlook; we must strive for a practical and achievable safety level that is acceptable by us, as a society.

The next logical question is: as a society, how safe should we expect our buildings to be? What level of risk should we accept for our buildings?

Our regulators have been struggling and shying away from setting an acceptable level. They are probably daunted by the unpleasant reality that acceptance of a safety level would necessitate the acceptance of the corresponding level of possible harm, which counters the former like a balance scale – and one can’t exist without the other. This, though logical, is politically unpalatable; and the reality is harsh and unwelcome.

But we must be reasonable. We can’t design for absolute safety. Neither can we, as a society, afford to pursue unrealistically high targets. It is an ethical, emotional and economic decision to set an acceptable level. Design that ensures buildings are safe is an investment, and an initial small investment in design will provide a high return. But the law of diminishing returns would dictate that increasing investment would eventually yield smaller and smaller returns, and ultimately tends toward the unreachable asymptotic limit of absolute safety.

A logical acceptable level of safety would be one that is no worse than the high level we enjoy now, and that provides the best bang for our societal investment in terms of making buildings safe.

Many studies have been conducted in the area of fire safety engineering to investigate cost-effectiveness of safe design, performance-based design, quantification of a safety level, societal acceptance levels and tolerable risk levels. We now have the tools and the knowledge. What we need is to explicitly set a quantifiable safety level in our regulations so that we may design our buildings to attain a uniform, transparent, high level of safety. This is what we should absolutely expect – not absolute safety.