|Developing a performance-based building code in Japan
|...by Dr. Vytenis Babrauskas, Fire
Science and Technology Inc.
|The United States, through the newly-formed International Code Council (ICC)
is developing a new, unified model building code. This code will contain two
tracks: a prescriptive track and a performance-based track. The ICC is still in
the early stages of formulating this performance-based track.
The U.S. is not the first country to engage in such an effort--in fact, it is
one of the last major industrial countries to start such work. This is not a
disadvantage, since the experience gained from examining previous efforts can be
applied. Such earlier efforts have been noted in Australia, New Zealand, Canada,
the United Kingdom, the Nordic countries (under their NBK umbrella group) and
other places. Also, an effort has been going on internationally, under the
auspices of the International Organization for Standardization (ISO), whose TC
92/SC4 has been producing documents on this theme.
Work on developing a performance-based approach has gone on in Japan since
1983. Here, we will specifically only examine the fire aspects of
developing a performance-based building code. The present author is the official
U.S. delegate to the current effort by Japan's Ministry of Construction (MOC) to
develop rational bases for fire safety design on performance-based principles.
The purpose of this short paper is to examine some highlights of the Japanese
activity and to point out how certain lessons learned there could be applied
towards the U.S. effort.
|The SOPRO project
|Japan is now in the second round of development of building regulations based
on fire-safety engineering (FSE), i.e., performance-based design. The first
round was completed in 1988, when a four-volume Manual of Practice was
published. That work addressed itself in the context of the Japanese Building
Standards Law Article 38, which is an 'equivalence clause,' authorizing the
approvals of designs which are equivalent to the prescriptive norm
embedded in the law. A notable limitation of that approach was that equivalent
FSE techniques, as set out in the Manual of Practice, had to demonstrate
equivalency on a paragraph-by-paragraph basis. This, of course, is restrictive,
since ideally a performance-based design should only need to demonstrate
equivalent overall safety for the entire structure.
In response to the seen limitations of the earlier scheme, in 1993 the
Japanese Ministry of Construction commenced a new 5-year project on this topic.
The project is called SOPRO, denoting 'Sogo Gijutsu Kaihatsu Project,' which
means Comprehensive Project for Technical Development. The project is run by the
ministry's Building Research Institute, with the work being done co-operatively
by BRI staff and Japanese industry. The present author has participated in this
work as the U.S. expert assigned to the supervisory committee of the project.
The SOPRO project has a completion date of 1998. The projected date for
implementing a performance-based track into the Japanese building law is the
year 2001. During the subsequent three years after the SOPRO project is
completed, two activities are planned: (a) technical work is expected to
continue in a "follow-on SOPRO," which will be launched in 1999 for either a 3-
or 5-year period. This one will be slightly narrower in scope, focusing on fire
+ earthquake issues. (b) Decision-making on implementation will start within a
new Council for the Promotion of New Construction Structure Systems. The latter
was constituted in 1996, but has not yet had much to do, since the technical
SOPRO work is not complete.
|The elements of SOPRO
|The basic elements of SOPRO include:
- The replacement of internal Japanese fire test methods by ISO standards.
- The technical improvement of test methods, including new inventions, as
- The development of new performance-based design guidelines which only
maintain an overall equivalent level of safety to the current prescriptive
- International co-ordination
The first two elements concerning test methods are further subdivided
into 3 work groups:
The last element is, as of this date, still relatively sketchy. That element
objectives are primarily to establish systems for: (a) international mutual
acceptability of fire test results, and (b) international mutual recognition of
fire test laboratories. The element also includes some very extensive survey
studies by Japanese researchers of Western building regulations, quality
assurance systems, test methods, laboratory accreditations, and design
practices. Thus, some of the output of this element is indirect, serving instead
to guide the work on the other portions of the work programme.
- reaction-to-fire tests
- structural fire performance
- assessment of building mechanical equipment
In this paper, we will focus on the element which comprises the development
of new performance-based FSE guidelines.
|The SOPRO approach to a Code of Practice
|The analysis presented below is of the current working draft of SOPRO's Code
of Practice for performance-based FSE guidelines. This draft was produced in the
Fall of 1995 and is about 60% complete. The final completion should take place
The general objectives of the FSE component of SOPRO are set out as:
The SOPRO approach has been to consider that a Code of Practice for a
performance-based design should consist of:
- Ensuring transparency of requirements and standards
- Maintaining an overall level of safety equal to that of the previous
- Introducing performance-based standards
- Ensuring consistency of standards.
- specified loadings
- specified safety factors
- mandated fire scenarios, and
- quantitative criteria, expressed as equations explicitly describing the
|Comparison to some existing Western approaches
|The above bare-bones description of the Japanese approach would suggest a
rational, non-controversial philosophy for developing a building code based on
performance considerations. Yet, in the Western world notable examples have been
of an entirely different ilk. Possibly the two best-known and most influential
approaches have been those put forth by ISO and by the UK. Those two approaches
are, in fact, less than independent: the committee membership of the two groups
had some pivotal overlap and many similarities are seen. The UK proposal has
been published a proposed Code of Practice as: Fire Safety Engineering in
Buildings (DD 240), British Standards Institution, London (1997). The ISO
proposal has, as of this writing, been approved but not yet printed. It will
comprise an eight-part document, entitled Fire Safety Engineering, and
numbered ISO 13387 through ISO 13394.
The most striking feature of both of these Western documents is that they are
totally non-mandatory and lack quantitative criteria. In the BSI
document, it explicitly states that "At an early stage of the design process,
the objectives of the fire-safety design should be clearly defined and the
acceptance criteria established." In other words, permission is given to the
architect to select both his own level of safety and his own criteria for
demonstrating he has achieved an adequate design. In practice, one has to
presume that if the BSI CoP is adopted, that local building officials will place
some limits to this freedom. Nonetheless, it is clear that in the BSI view,
neither a national level of safety, nor nationally-applicable criteria are
The ISO approach is perhaps even vaguer, since the level of safety is nowhere
considered, let alone mandated. The designer is basically instructed to design
various aspects of fire safety "adequately," with no notion given of how
adequacy will be determined or enforced.
In the view of the present author, the enunciating of pass/fail criteria is
essential to the functioning of a performance-based building regulation. Once
the phenomena have been quantified and numbers are presented, it must become
clear whether or not the expected criteria are met. In the BSI/ISO
approaches, this is not made explicit and is deferred to some subsequent
evaluation process. This philosophy is likely to create significant uncertainty
and difficulties in implementation. Essentially, the BSI/ISO approaches only
quantify certain features of the fire/building/human interaction. They provide
no benchmark against which to judge if the outcome is bad, good or borderline.
But if the issue of "what is good enough performance" could not be successfully
determined by the assembled experts in the BSI and ISO committees, there does
not seem to be much chance that such judgements could be adequately made by
officials reviewing building plans.
The SOPRO approach, on the other hand, makes it clear that the criteria
must be built in to the system of equations. The officials reviewing the
plans have to scrutinize the designs to make sure that they indeed conform to
the performance criteria demanded, but they are not presented with the
impossible task of formulating performance criteria. (The alternative, of
officials simply accepting performance criteria proposed by building architects,
seems hardly adequate or equitable).
Compared to the BSI/ISO approach, there are two essential differences, one on
a policy level and one on an engineering level. The policy issue is identified
in objectives 2 and 4 above: The SOPRO developers insist on a specified level
of safety, and this level of safety must be nationally applied. In parallel,
Objective 4 ensures that the standards (i.e., criteria) are also nationally
applied. Thus, from an engineering viewpoint, the most striking difference
between the SOPRO approach and that of BSI/ISO is the way that the developers
have approached the technical task. The BSI approach was to subdivide the
necessary fire performance into small elements, then to seek published
scientific equations for computing the physical phenomena involved in each
element. The 'work output' can be seen to be mainly this collection of equations
for a multiplicity of fire phenomena. The ISO approach originally was identical,
but the final balloted documents lean towards simply providing references to
equations, rather than actually listing equations.
Another aspect in which the Japanese work is different from the Western
approaches is in its treatment of the research base. In the BSI/ISO proposals
(and in many other Western schemes) the developers have only taken on themselves
to cull the scientific literature and to cite suitable formulas. Where a
phenomenon has been inadequately studied, the Code of Practice simply contains a
placeholder. The Japanese philosophy, on the other hand, considers that in such
cases a focused, short-term research project must be mounted. This
philosophy was already operable during the predecessor Manual of Practice in
1988 and is equally operative during the SOPRO work.
|Some examples of SOPRO innovative approaches for FSE
|Since the SOPRO work is still incomplete, it is too early to make any
conclusions about the merits or the operability of the whole approach. What can
be done even at this stage, however, is to look at some examples of innovative
approaches which have already been incorporated into their draft document. The
examples cited below are of special interest because they represent creative
problem-solving and do not take a similar approach to established Western
(a) Fire compartmentation
In Western building regulations, the logic behind fire compartmentation tends
to be very opaque. It is clear to all that the reason for it is that a
limited-size fire may be possible for fire services to control, but beyond a
certain size, their capabilities may be overrun. However, the engineering
requirements to achieve this generally do not exhibit much logic and are viewed
as legal heritage. The situation in Japan has been not too different. With the
SOPRO work, at attempt is made to establish compartmentation on a rational
basis. One of the main chapters of the document is entitled "Fire safety of
compartments," and it encompasses not only room/floor subdivisions, but also
atria, multiple buildings in a connected complex, and similar geometries. Unlike
in today's approach, the objective here is not to merely satisfy the
requirements of a fire resistance test, but rather to rationally provide for
limits to heat and smoke entering from one compartment to another or else
structural damage propagating to another. A special treatment is given to
computing the viability of compartments which are to serve as shelters.
(b) Building occupancy
Today building regulations view occupancies on the basis of whether the
building is a hotel, a factory, a school, etc. The SOPRO approach sets out a
multi-dimensional classification scheme for building occupancy:
One novel way this classification scheme is used is to develop the starting
time for when the occupant becomes able to commence escape from fire. The
present draft of the document does not yet go into much other detail how this
occupancy classification scheme will be used, but such a scheme may have
significant merit if suitably developed.
- sleeping: yes/no
- main population: able-bodied or not
- familiarity: are most persons in building intimate with its layout?
- density of people
- fuel loading
- combustibility of fuel load
- hazard of ignition occurring
(c) Firefighting access
The Japanese, even in the current regulations, have quantified more aspects
of firefighting access than is normally seen in the West. In the new SOPRO Code,
for example, there is an explicit classification of roads around buildings into
ones which are needed for firefighting access, versus ones which are not. For
the roads which are needed for access, special structural provisions are made to
ensure that the building will not collapse onto the road for the whole duration
of the fire.
|A flexible strategy with built-in provisions for future refinement
|Despite the concerted work being done in the SOPRO project, it is realized
that even upon the completion of the project, fully-ideal performance-based
methods will not be available for all aspects of building fire safety. Thus, the
authors define 5 different types of safety standards:
P Performance-based criteria
C Complementary criteria [=simplified performance criteria]
D Deemed-to-satisfy criteria [=tentative criteria, to be worked upon later]
S Specification [= prescriptive] criteria
E Expert-opinion criteria
The P criteria will encompass the fully performance-based aspects. The C
criteria are either partly-empirical computation methods, or else simplified
criteria for use in smaller buildings, where extensive calculations may not be
justified. The categories D and E are interim measures, where it is recognized
that a need exists for a more performance-based approach, but such a one is not
ready yet. A certain amount of S criteria will remain for practical reasons.
Examples of each may be given:
P criteria. The heat to which the escaping occupants are being subjected
on the exit path is expressed as a computational formula, to be determined from
an analysis of fire conditions, walls, leakage from openings, etc.
C criteria. Requirements are prescribed for areas of refuge which are
located in enclosed open-air courtyards and the like. One of the requirements is
a formula which relates the distance the refuge must be from the building, vs.
the building height. This is to prevent evacuees from being hit by falling
debris from the burning building.
S criteria. The dimensional requirements for row spacing of theatre seats
is given as an S criterion. This is because such numerical values have already
been proven out in use, and there is no reasonable basis for proposing a varying
E criteria. There may be no objects which can fall on top of evacuees
along the exit path.
|Some examples of SOPRO innovative approaches in the fire testing area
|While the present paper focuses on the Japanese efforts in developing FSE
criteria, it is worthwhile to cite some of examples of the use of focused,
short-term research in the fire test area.
- During the course of some investigations at the Building Research
Institute, the researchers found that walls with grooves in them tend to have
quite different fire propagation characteristics from flat walls. Such walls
are often specified by architects in auditoriums. The final SOPRO report is to
contain special provisions for the testing and analysis of such wall surfaces,
based on equations being developed for this case.
- The use of intermediate-scale heat release rate test equipment is just
starting to be considered in ISO. Such work has been going on in Japan for a
number of years, however, and criteria based on it are expected to be included
in the final SOPRO report. For the majority of products, small scale testing
according to the small-scale ISO 5660 Cone Calorimeter will be entirely
adequate. For validation work and for highly unusual structures, large scale
testing according to the ISO 9705 room test is necessary, and this test is
being considered by the European Commission as the benchmark for fire
propagation assessment. There are products, however, whose irregularities can
make them unsuitable for small scale testing, yet which do not present novel
performance issues requiring large scale testing. The Japanese researchers
have been aware of this issue for a number of years, have built intermediate
scale apparatuses, and are now developing relevant performance criteria.
- A procedure for medium-temperature testing of fire doors exists in draft
form in ISO (CD 5925-1). Very few European laboratories have implemented this
test. The Japanese researchers investigated the test and the suggested
construction drawings for the test furnace. They concluded that the design is
not viable and launched a small project to develop a practical furnace design
which could achieve the objectives of the test. This has now been completed
and a number of tests have been made with the equipment. It is their intention
to feed this information back to ISO.
|Lessons to learned from the Japanese work
|The Japanese SOPRO work has suggested a very different model for establishing
performance-based fire safety requirements than some of the better-known Western
examples. The Japanese approach recognizes that for an FSE approach to be
incorporated into a viable building regulation scheme, it must explicitly
The above lessons can be directly applied, if desired, to the ICC process in
the U.S. The technical details, i.e., the exact criteria themselves, do not have
to be copied from the Japanese. What is important to accept is that quantitative
criteria are needed and that fire scenario selection cannot be left up to
individual designers but must also be mandated on a uniform basis.
- a uniform minimum level of safety, independent of who designed the
building or which official reviewed the plans.
- specified loadings, safety factors, fire scenarios (as a minimum; the
architect, of course, remains free to design a higher level of safety if asked
for by his client).
- explicit, quantitative evaluation criteria.
|This article Copyright © 1997 by Vytenis Babrauskas.