FIRE SAFETY OF BUILDINGS
Trends and the role of CIB W14

Matti Kokkala
Coordinator of CIB Working Commission W14: Fire

INTRODUCTION

Fire safety has always been an essential requirement for buildings. Even before it was consciously recognised, balance has been sought between the cost of fire accidents and the cost of providing safety. With increasing economic resources and the increased value of human life, fire safety requirements of societies have slowly increased. While urban conflagrations were once a regular nuisance, they now have become a rare event.

Despite the positive developments, fire is still a major problem to society. In the industrial world, there are still typically 10 to 20 fire deaths per million population per year. The direct fire losses are 0.1 to 0.2% of GNP. The total cost of fire prevention and consequences of fire are typically 10 times the cost of direct losses.

Fire science and fire safety engineering are multidisciplinary subjects building on the solid backgrounds of several other fields, including combustion, fluid mechanics, chemistry, structural mechanics and human behaviour. Although fire is a common phenomenon, scientific research in fire has been quite rare in the world. Until the 1970's most of the work was on the response of structures and materials to fire exposure. Since then, fire research fields have expanded rapidly. One of the key forums for the exchange of research result has been CIB W14. During the last two decades, the understanding of fire has also increased significantly. The first university-level textbook on fire dynamics was published only in 1985. The same year the International Association of Fire Safety Science was founded to promote fire science and to bring the individual fire scientists of the world together. The FORUM for International Cooperation on Fire Research was formed only in 1988.

Many of the innovations in fire science are gradually turning into engineering tools making it possible to accomplish and control fire safety of buildings in completely new ways. The more efficient use of resources and greater flexibility have been the result of these innovations.

THREATS TO FIRE SAFETY

Dark clouds can be seen to threaten the positive developments in fire safety. The ageing of the population will require better fire safety. The size and complexity of buildings are increasingly making the potential maximum losses larger. In rapidly developing countries, the number of fires is increasing at a rate at least as high as the growth rate of economy. The shrinking of public sector resources for fire safety almost everywhere in the industrialised world also means a decrease in fire fighting and rescue personnel.

One must also fully realise that the consequences of decisions made today will appear in the fire statistics only after ten or twenty years and thus the full use of existing scientific knowledge is needed even more to ensure that future losses continue to decrease with the application of the new developments.

FIRE SAFETY REGULATIONS

Fire safety regulations for buildings have traditionally been prescriptive allowing at best alternative approaches as exceptions. Construction products have had to be tested and classified for their ignitability, flame spread characteristics, combustibility, smoke production propensity, fire resistance, etc. The current regulations ask for specified product classes for different occupancies making the regulations often a complex set of tables.

For several years, the trend has been to make fire safety regulations for buildings performance-based. For a majority of the cases, the prescriptive method would still be an accepted way of demonstrating the safety of a building. The designer, however, would also be given an option to assess the safety of the building against a performance standard. The performance-based approach demands much more from the designers and approving bodies, but they also offer greater design and operational flexibility and possibilities for substantial savings. It has been estimated that performance-based regulations would mean savings of approximately 5% in the total cost of construction without any recognisable change in the safety level. Experiences from countries like New Zealand, Australia and Sweden are also demonstrate a dramatic change in the culture in the culture; instead of arguing about numbers, the approval process has now turned into a discussion about fire safety.

TESTING AND PRODUCT APPROVAL

There have been significant advances in laboratory methods to measure the fire behaviour of products. It seems, however, to be a very slow process to get these advanced methods into recognised standards to be used as a basis of product approval. Too often, we still find that those requesting standards prefer to rely more on empirical methods than on methods based on sound scientific principles.

Although efforts to harmonise standards have been extensive, it will still take years until the long-awaited reduction in the need of repeated testing for different markets begins to diminish. With changes, like those occurring in Europe at the moment, it is probable that the volume of fire testing will even increase over the next five years, despite the advances in generic scientifically-based methods.

TECHNICAL DEVELOPMENTS

Fire behaviour is one of the significant boundary conditions for product development. In many cases, products are being developed to meet the fire specifications with cheaper solutions. Every year, numerous patents for new fire retardants and fire retarded products are being issued. Only a few of these products become commercially successful, although it has been estimated that the fire retardant market is growing at a rate of 4% per year. New environmentally friendly and economically viable fire retardants would no doubt find a good market.

Active fire safety technologies have also been experiencing a rapid change over the last ten years. Detection systems have become more intelligent, causing fewer false alarms and making it easier to locate the source of fire even in complex buildings. Even the use of water found a sudden increase of interest in the 1990's. Water mist systems with smaller droplets than normal sprinklers have proven their efficiency and a great number of applications have emerged. The world-wide market for these systems is still growing rapidly.

The development of fire simulation models have substantially changed the way fire hazards can be assessed. User friendly tools are available to simulate the development of fire under different conditions.

Perhaps the biggest change in the way the fire safety of buildings is being done is due to the development of computer codes for the simulation of fire growth and smoke movement. While the fire safety was earlier based on the performance of components, the computer codes can now be used to study the consequences of a given design fire or the influence of various features of design. Unnecessary redundancy in the fire safety measures can therefore be avoided, and often substantial cost reductions can be achieved.

NEED FOR HIGHER FIRE SAFETY EDUCATION

There are only a few academic institutions in the world with specialised fire safety engineering programmes. Ironically, it is difficult to find any other field of engineering, with similar economic and societal impact, having so little higher level education. A lack of qualified engineers automatically makes it difficult to introduce new tools into practice. There is wide international agreement that a typical civil engineering graduate needs at least one year of full-time studies with appropriate practical training to be able to make full use of the new calculation methods and to make appropriate engineering judgements.

Architects and structural engineers have been suffering from the recession in the construction industry in many countries. Professional fire safety engineers have fared much better because they can often apply their skills not only to the buildings sector but also to the process industry, ship building and other areas. It is commonly predicted that the market for properly educated fire safety engineers remains good well into the foreseeable future.

RESEARCH NEEDS

Like other research institutes, all fire research organisations around the world are facing more commercial pressures. While the 1970's and 1980's were a time of increased work on the basics of fire science, the 1990's have seen the research laboratories focus more and more on transferring the research results into practice, because the research results have not yet reached the end user.

The current turmoil on the standardisation of test methods has increased the demand fire research to support the development and application of these test methods. This has especially influenced the fire research carried out at building research institutes. It is expected that this turmoil will continue for at least another five years.

The trend toward performance-based fire safety regulations has already initiated major research efforts in several countries, e.g., Australia, Japan, USA, Canada, UK and the Nordic countries. Although a large number of useful engineering tools to support such tools are already available, development is still needed in many fields, e.g., calculation methods taking into account human behaviour or suppression effects. The risk-based approach requires the implementation of reliability engineering methods to fire safety assessment.

INTERNATIONAL RESEARCH POSSIBILITIES

Although the building regulations in different countries treat fire safety in many different ways, the natural laws controlling fire are the same everywhere. Many of the problems are therefore common to the whole world and solutions can be found through international co-operation.

Some of the key issues of fire safety are of such magnitude or type that one institute or even the institutes of one country cannot satisfactorily complete. For example, the verification of calculation methods for fire growth and smoke movement require an extensive series of heavily instrumented large-scale tests to be run. The whole series is likely beyond outside of the resources of any one nation. As well, verification of test methods by interlaboratory calibration exercises requires multinational co-operation by nature.

While the exchange of information within the fire research community has improved vastly, there is still a lot to be gained by joint, well-coordinated international projects. For example, in Europe there are successful multinational fire research projects on such topics as industrial fires, furniture fires, cable fires, fire safety of offshore structures, and forest fires. Within building sector, the joint efforts have been primarily limited to test method development or to the assessment of fire behaviour of limited types of structural elements. Except for projects sponsored by steel industry and the steel research programmes, cooperation on the development of methods for fire safety assessment has been rare.

The globalization of world trade also leads into a need of increased global cooperation in research. Because fire research is often done to support standards and regulations, the consequences of lack of co-operation are evident. By joint efforts, common methods of fire safety assessment would be created, and thereafter the existing barriers of trade could be removed. International research organisations like CIB and FORUM for Cooperation in Fire Research are the natural bodies to take a lead in these activities.

THE ROLE OF W14

The goal of CIB W14: Fire is to provide ongoing research focus for the development of a sound technical basis for fire safety engineering methods, and to promote the acceptance of the methods and their relationship with performance based codes. To achieve the goal, we have initiated several projects with well-defined scopes and limited time schedules and arranged workshops together with other organisations like the Society of Fire Protection Engineers working towards the same goal.

In one project, the problems of engineering evaluation of building fire safety have been studied. The purpose is, e.g., to provide guidance on performance criteria, such as design fires or occupant characteristics, appropriate to the evaluation of the risk of death or injury from fire.

Two of the projects aim at creating a rational process for the verification of calculation models. In the case of computer codes simulating smoke movement, an extensive round robin exercise with 21 partners from 11 countries is in progress. New work item is under discussion to study the quantification of uncertainty of fire safety assessment methods in general. For models to predict the thermal response of structures, a series of test examples has been proposed for the computer code developers to check the numerical accuracy of their code. Planning is going on to extent this to cover also the models for load-bearing capacity of structures in a fire.

Fire safety engineering also needs reliable methods to give necessary input data. Therefore, an experimental project has been started to improve the quality of fire growth measurements. As a first step, a project has been carried out on the reproducibility of the Cone Calorimeter, which is the main method used to produce input data on the burning behaviour construction products for fire growth calculation methods.

Although CIB is working on a voluntary basis, it has been and could be used even more as an impartial forum to create extensive projects with world-wide participation.

ACKNOWLEDGEMENT

The author wishes to thank Members of W14 for their responses to a questionnaire sent out earlier this year and several members of the FORUM for International Cooperation in Fire Research for useful comments on the manuscript of this paper.

September 1996

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