performance-based fire safety design in the united kingdom · –allows for alternative fire safety...
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Performance-Based Fire Safety
Design in the UNITED KINGDOM
Cecilia Abecassis Empis
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TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
OVERVIEW
2ORADOR
• Performance-Based Design
or Fire Safety Engineering
• Framework within Regulations
– AD B
– BS 7974
• Fire Safety Engineering designers
• Licensing Process & Legal Context
• Competence for Fire Safety Engineering Process
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
Goals
Functional
Objectives
Performance Requirements
Approved
Calculation
Method
Acceptable
Solution
Performance-Based
Alternative Solution
Prescriptive Standards:
Dictates how a building
should be designed/built
Performance-Based
Design Standards:
Stipulates how a building
should perform under a
number of different
conditions/scenarios
Under
development
Life Safety (& property/environmental protection)
Limit Fire Spread
Appropriate means of
detection and evacuation
Evacuation
times
Compartmentation
Guarantee structural
stability
Limit smoke toxicity
Smoke management
Structural protection
* Buchanan, A.H. (2002) Structural Design for Fire Safety, John Wiley & Sons, Ltd.,
U.K.
PERFORMANCE-BASED DESIGNaka FIRE SAFETY ENGINEERING
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
Prescriptive Standards:
Dictates how a building should be
designed/built
Performance-Based Design Standards:
Stipulates how a building should perform
under a number of different conditions
- Group of clauses often
based on empirical values
- No explicit evaluation of
level of safety
- In general appropriate for
generic buildings
- Analytical engineering
calculations
- Provides an explicit measure of
level of safety
- In general appropriate for
unique/singular buildings
* Buchanan, A.H. (2002) Structural Design for Fire Safety, John Wiley & Sons, Ltd.,
U.K.
PERFORMANCE-BASED DESIGN
Goals
Functional
Objectives
Performance Requirements
Approved
Calculation
Method
Acceptable
Solution
Performance-Based
Alternative Solution
aka FIRE SAFETY ENGINEERING
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
• General Fire Safety requirements set out in
Approved Document B (AD B):
– Prescriptive standard
– Allows for alternative Fire Safety Engineering solutions
– References other codes and standards for design of
specific sections
• Alternative Fire Safety Engineering approach set out
in BS 7974:2001:
– Applications of fire safety engineering principles to the
design of buildings – Code of Practice
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AD B & BS 7974
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
• Approved Document B (Fire
Safety), introduced in 2000
• Two volumes:
– Vol.1 Dwellinghouses
– Vol.2 All other building types
• Clearly states functional
objectives
• Initial guidelines emphasise
alternative fire safety engineering
solutions can be used
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AD B
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
• Functional Objectives (AD B):
– B1. To ensure satisfactory provision of means of giving and alarm of fire and a
satisfactory standard of means of escape for persons in the event of a fire in a
building
– B2. To ensure fire spread over the internal linings of buildings is inhibited.
– B3. To ensure the stability of buildings in the event of fire; to ensure that there
is a sufficient degree of separation within buildings and between adjoining
buildings; to provide automatic fire suppression where necessary; and to inhibit
the unseen spread of fire and smoke in concealed spaces in buildings.
– B4. To ensure external walls and roofs have adequate resistance to the
spread of fire over the external envelope, and that spread of fire from one
building to another is restricted.
– B5. To ensure satisfactory access for fire appliances to buildings and the
provision of facilities in buildings to assist firefighters in the saving of life of
people in and around buildings.
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Goals
Functional Objectives
Performance Requirements
Approved
Calculation
Method
Acceptable
Solution
Performance-Based
Alternative Solution
AD B
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
• AD B allows for Approved Calculation Methods
and Performance-based Alternative Solutions:
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Goals
Functional Objectives
Performance Requirements
Approved
Calculation
Method
Acceptable
Solution
Performance-Based
Alternative Solution
AD B
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
• AD B suggests Fire
Safety Engineering may
be the only way of
achieving adequate level
of safety in large and
complex buildings
• Suggests FSE can be
used to solve single
aspects of design or
whole strategy
• Refers BS 7974:2001
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AD B
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
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AD B for Fire Safety Engineering
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
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AD B for Fire Safety Engineering
• No more reference to PBD and
FSE in ADB
• Layout of the document makes
‘localised’ PBD very
straightforward
• Breakdown makes identifying
intent/objective of individual
clauses easy
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
• BS 7974 introduced in 2001
• In 8 parts:
– General guidance
– Parts for specific sections of fire safety
strategy
• BS are guidance and
recommendations – should not
be quoted as if it were
specification;
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BS 7974
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
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BS 7974
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
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BS 7974
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
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BS 7974
• The BS 7974 framework:
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
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BS 7974
• Essential to understand the intent of the code
• BS 7974 starts with a Quantitative Design
Review (QDR):
– Consider intent of each relevant recommendation
– A particular provision may have more than one
objective
– Develop alternative design solution
– Iterate until demonstrate proposed solution at least
as effective and reliable at meeting intent as the
conventional prescriptive approach
– Design team can include members of the approvals
bodies
• QDR should start at conceptual project phase
and be iterated, as necessary, as project
develops to detailed design phase
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
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BS 7974
• QDR Procedure:
– Review Architectural designs
– Establish fire safety objectives
– Identify fire hazards and possible consequences
– Establish trial fire safety designs
– Identify acceptance criteria and methods of
analysis
– Establish fire scenarios for analysis
• Quantitative Analysis, either:
– Deterministic design procedures
– Probabilistic design procedures
• Assessment against criteria:
– Deterministic, probabilistic, or comparative
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FRAMEWORK WITHIN REGULATIONS
• BS 7974 also makes recommendations on:
– Sub-systems (Parts 1-7) and how parameters of
design may interact (inter-dependency)
– The outline of report contents
• Emphasises the report should draw clear distinction
between life safety, property protection and
environmental protection
• It is assumed in the preparation of this BS that “the
execution of its provisions is entrusted to appropriately
qualified and competent people”
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BS 7974
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
FSE DESIGNERS
• No specific qualification requirements currently exist in
the UK for FSE designers
• For individual products and components certification schemes exist
• Accreditation of Installers and Maintenance firms
– Provides confidence in appropriate standard of workmanship, as fire performance of a
product, component or structure is dependent upon satisfactory site installation and
maintenance
• Third party accreditation of product and installation
conformity provide extra confidence in adequacy of systems
installed
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Who is appropriately qualified and competent to practice
Fire Safety Engineering (PBD)?
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
LICENSING PROCESS & LEGAL CONTEXT
• Building Control Bodies to accept adequacy of FSE
solutions (and product/component certifications) as
evidence of compliance with the relevant standards
• Legal responsibility therefore lies with the approvals
authorities
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…but the question of competence remains!
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
COMPETENCE FOR FSE PROCESS
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• Competence required to evaluate whether alternative solutions
comply with intent of the code:
– Fire Dynamics
– Heat Transfer: radiation, convection & conduction
– Compartment Fire Modelling (zone models, empirical & analytical
correlations)
– Background to empirical tools so can identify limits of applicability
– Fluid Dynamics & turbulence (for adequate use of CFD tools)
– Structural behaviour under transient and elevated temperatures
– Understand theory behind standard testing methods and material
behaviour under exposure to fire and different forms of heat exposure
– Understand limits behind behavioural modelling, etc….
What competence is needed to practice and approve
Fire Safety Engineering (PBD)?
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
COMPETENCE FOR FSE PROCESS
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• Those who practice Fire Safety Engineering in the UK:
– Usually Engineers
– Historically: with university degree in Engineering, Physics or
Chemistry
– Nowadays: with university or Postgraduate degrees in Fire
Safety Engineering
• For system to work, the Approval Authorities need same or
higher level of qualifications
• Authorities need the same or higher level of competence as
Professional Fire Safety Engineers
• Currently authorities often rely on Third Party Reviews by
Professional Fire Safety Engineers
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
COMPETENCE FOR FSE PROCESS
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• Authorities need same or higher level of qualifications and
competence as Professional Fire Safety Engineers
• Authorities often rely on Third Party Reviews by Professional Fire
Safety Engineers
• Authorities ultimately still assume legal responsibility!
• How to judge competence of Third Party Reviewers?
• Structural Engineering works on self-certification
• Chartered Structural Engineers sign-off on projects and take
responsibility, backed by their charter institutions
• Adequate National and International Chartering Bodies are
necessary to evaluate engineering competence of FSE engineers,
for an effective system
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
SUMMARY
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• UK Legislation allows for Performance-Based
Design or Fire Safety Engineering
• FSE designer must ensure proposed solutions
comply with the intent of the codes (functional
objectives)
– Whether Prescriptive solutions are applied
– Or an alternative Performance-Based Design
• Building Control Bodies (authorities) approve FSE
designs and are legally responsible
• Authorities often rely on Third Party Reviews by
Professional Fire Safety Engineers
TÆCRESEARCH • DEVELOPMENT • DESIGN • EDUCATION
Cecilia Abecassis Empis, PhD MEng
Director & Senior Engineer
TORERO, ABECASSIS EMPIS and COWLARD Ltd
E | [email protected] | W | www.taec.engineering
RESEARCH • DEVELOPMENT • DESIGN • EDUCATION