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Contents
  1. 1Principle and terminology
  2. 2Reasons for using it
  3. 3The design process
  4. 4Comparative and absolute approaches
  5. 5Acceptance criteria and safety margins
  6. 6Verification, competence and the building life cycle
  7. 7Limits and criticism
  8. 8See also
  9. 9Notes
  10. 10References

Performance-based design is an approach to fire safety design in which measures are chosen for a specific building and then shown by engineering analysis to meet stated objectives or performance requirements.[1][2] It is the alternative to following a prescribed set of rules. Building codes that allow this approach state what a building must achieve and leave open how it is achieved.[1] In Australia, a design developed this way is called a Performance Solution, and it is unique to each situation.[3]

Performance-based design grew out of the limits of prescriptive codes, which cannot cover emerging technologies and every combination of circumstances.[4] It is applied through fire safety engineering. The engineer and the stakeholders agree the objectives, fire scenarios, design fires and acceptance criteria. One or more trial designs are then analysed until one meets the criteria.[5]

The analysis may show that a design is at least equivalent to a design that complies with the prescriptive provisions, or that it meets the performance requirements directly.[2] The freedom of the approach comes with costs. The performance requirements of many codes are not quantified, the results are hard for authorities to check, and the design depends on the building being managed as assumed.[6][7]

Principle and terminology

The core idea is to regulate the outcome rather than the means. The International Fire Engineering Guidelines (IFEG, 2005) explain that the intent of building regulations is to reduce risks to a level that the community tolerates.[4] Traditional codes did this with prescriptive rules. Because such rules constrained designs in ways that did not always suit the building, codes became performance-based, to free designers, increase innovation and facilitate trade.[4] The opposite approach is described in the article on prescriptive design.

Performance-based codes are usually arranged as a hierarchy. In the Building Code of Australia described by the IFEG, objectives and functional statements state in general terms what the community expects and how a building could satisfy it.[8] Below them are the performance requirements, which every design must meet but which are not quantified.[6] A design that complies with the deemed-to-satisfy (DTS) provisions is deemed to meet the performance requirements. A design that differs and is shown by analysis to comply was called an Alternative Solution.[6]

Pyramid: objectives, functional statements, performance requirements; below, two routes: deemed-to-satisfy solution and performance solution.
Hierarchy of a performance-based building code: the performance requirements are met either by deemed-to-satisfy provisions or by a performance solution shown to comply by analysis. Based on National Research Council of Canada et al. (2005), pp. 0.2-2–0.2-3 and Australian Building Codes Board (2020b), p. 13.

The terms differ between countries. The current National Construction Code (NCC) of Australia uses Performance Solution for what earlier editions called an Alternative Solution.[9] The NCC is performance-based, and a design may use a Performance Solution, a DTS Solution, or a combination of both.[1]

In New Zealand, the Building Code sets objectives, functional requirements and performance criteria. Compliance can be shown with an acceptable solution, a verification method such as C/VM2, or another means.[10] In the Netherlands, a risk-based alternative to the prescribed measures of the building regulations is usually called equivalence. It must achieve at least the same level of fire safety as the measure it replaces.[11]

Reasons for using it

The main advantage is freedom of design. The Australian handbook for the Fire Safety Verification Method (FSVM) points out that a performance-based code imposes no obligation to use any particular material, component or construction method. The only condition is that the performance requirements are met.[1] Performance Solutions are often flexible in achieving the outcomes and encourage innovative design and use of technology.[3] A DTS Solution, by contrast, follows a set recipe of what, when and how to build.[3]

The IFEG list further benefits. They include a disciplined approach to fire safety design and a better understanding of how the parts of a fire safety system interact. Others are a method for comparing alternative solutions, monetary savings, and guidance for construction, commissioning and maintenance.[12] Fire engineering can also assess existing buildings when their use changes and propose solutions for upgrading them.[12]

Some buildings fall outside what prescriptive rules can handle. Introduction to Fire Safety Engineering notes that in the Netherlands, fire safety engineering is applied mainly to buildings that deviate from the norm. Examples are public transport terminals, tunnels, towers with a floor above 200 m, buildings with large atria, and large compartments outside the scope of the Dutch standards.[13] Even in ordinary buildings, an analysis may address a single aspect to represent reality better than the standard rules do.[13]

New Zealand gives an example of why a structured performance framework was introduced. A review of its Building Code found that the fire safety performance requirements were not clear or precise enough.[14] The lack of a consistent approach led to disputes over designs, stifled innovation, more conservative designs, and lengthy and costly debates about compliance.[14] The response was C/VM2, a verification method with prescribed design scenarios for complex buildings. Simple buildings remained covered by acceptable solutions.[14]

The design process

The IFEG describe a typical process in five stages: preparing a fire engineering brief (FEB), carrying out the analysis, collating and evaluating the results, drawing conclusions, and preparing the report.[15] The FEB defines the scope of work and the basis for the analysis, as agreed by the relevant stakeholders.[5] For a simple departure from a prescriptive provision it may be a short document, but for a large or complex project it can be a major one.[5]

Five boxes from fire engineering brief to report, with a loop from the conclusions back to the brief when a trial design fails.
The fire engineering process: if a trial design does not meet the criteria, the brief is revisited and a new trial design analysed. Based on National Research Council of Canada et al. (2005), pp. 1.1-2 and 1.2-2.

The FEB covers the scope, stakeholders, building and occupant characteristics, objectives, hazards and available measures, and the trial designs.[16] It also records the non-compliance issues, the approaches and methods of analysis, the acceptance criteria and factors of safety, and the fire scenarios and design occupant groups.[16] In principle, the objectives, trial designs, methods and criteria are all agreed before the analysis starts.[5] At this stage the design fires are described as far as possible without calculation, so the brief works as a qualitative review of the design.[17] If analysis later shows that a trial design is unacceptable, the brief is revisited and a further trial design is developed.[5]

Australian practice uses a performance-based design brief (PBDB), followed by a performance-based design report.[18] The report lists all variations from the DTS provisions and the performance requirements they affect. For each design scenario it states whether the proposal reached at least the safety level of a reference building that complies with the DTS provisions.[18] In New Zealand, C/VM2 (second edition, 2025) describes an example process. It runs from concept design and FEB to a trial design tested against ten design scenarios, which is revised until all of them are satisfied.[19]

Comparative and absolute approaches

A key decision in the brief is how compliance will be shown. In a comparative approach, the fire safety of the trial design is compared with that of an identical building designed to the DTS or prescriptive provisions.[2] Both are analysed with the same assumptions, models and input data, and the trial design must be equivalent or better. This is often called an equivalence approach.[2] In an absolute approach, the results are compared directly with the objectives or performance requirements using the agreed acceptance criteria, without a benchmark design.[2]

Two panels: left, trial design and DTS design analysed the same way and compared; right, trial design results compared with fixed criteria.
Comparative approach (left): the trial design must perform at least as well as an identical DTS design. Absolute approach (right): the results must meet agreed acceptance criteria. Based on National Research Council of Canada et al. (2005), p. 1.2-21.

The Australian FSVM requires a comparison with a reference building that complies with the DTS provisions.[9] The handbook explains that the reference building indirectly defines the acceptable individual and societal risk levels, so its choice must be agreed by all stakeholders.[20] An example shows why this matters. A Performance Solution for an apartment building extends the travel distance from an apartment door to a fire-isolated stair from the DTS limit of 6 m to 12 m.[20] A fair reference building with the same footprint and number of occupants would need two stairs under the DTS provisions. The proposal therefore both lengthens the travel distance and removes an exit, which changes the scenarios that must be analysed.[20]

Two floor plans of 12 apartments: left, one central stair with 12 m travel distance; right, the same floor with two stairs and 6 m limit.
Proposed design with one stair and a 12 m travel distance (left) and a reference building of the same size that complies with the DTS provisions with two stairs (right). Based on Australian Building Codes Board (2020b), pp. 46–48.

Analyses also differ in method. Qualitative analysis is used only in a minority of cases, for example for a single non-compliance issue, and its logic must be documented.[2] Most cases need a quantitative approach.[2] Deterministic methods, which always give the same outcome for the same inputs, are the most common. Probabilistic methods assign reliabilities and frequencies and combine many scenarios, but they need much statistical data.[21] Introduction to Fire Safety Engineering adds that both approaches have their own strengths and are often used together.[22]

Acceptance criteria and safety margins

Acceptance criteria turn the general objectives into tests that an analysis can pass or fail. The IFEG require them to be appropriate to the objectives and the methods, numerical unless the analysis is qualitative, and realistic.[23] Zero risk, for example, is not an appropriate criterion.[23] Typical parameters for protecting occupants are the expected risk to life, the margin between available and required escape time, smoke layer height, layer temperature, radiant heat, smoke optical density and carbon monoxide level.[23]

For life safety, the most common deterministic test is a timeline comparison. The available safe egress time (ASET) is compared with the required safe egress time (RSET), and ASET must exceed RSET by a margin agreed in the brief.[21] In a comparative evaluation, the margin of the trial design must be the same as or greater than that of the DTS design.[21] Introduction to Fire Safety Engineering notes that many inputs to both times are uncertain, so the safety margin is important. It can be expressed either as a factor on RSET or as a minimum difference between ASET and RSET.[24] The more reliable the inputs, the smaller the margin needs to be.[24]

Timeline from ignition: RSET bar ends before ASET bar; the gap between them is the safety margin.
The available safe egress time must exceed the required safe egress time by an agreed safety margin. Based on National Research Council of Canada et al. (2005), p. 1.2-22 and Van Rossum (2027), §7.1.

Factors of safety should reflect the redundancy and reliability of the design, the methods and assumptions, the uncertainty and the consequences of a fire.[25] They should be applied only at the end of a calculation, because applying them at every step leads to overly conservative results.[25] In a comparative evaluation, explicit factors are usually unnecessary because both designs are analysed in the same way.[25] Sensitivity studies test how the result changes when key inputs vary. Examples are a fire growth rate several times greater, partial failure of smoke exhaust, lower walking speeds or fewer available exits.[26]

Verification, competence and the building life cycle

Performance-based designs are harder to check than prescriptive ones. Introduction to Fire Safety Engineering points out that the justification can be so complex that the approving authority cannot easily verify it, unlike a rule-based design.[7] Computational fluid dynamics is given as an example: authorities often have no specialist in it, so the integrity of the fire safety engineer must be relied upon.[7] A second opinion is advised where results are unexpected or the party is unknown, but it is not economically feasible for every project.[7] The book also notes incentives, such as obtaining a permit or saving on construction and installations, that can make certain outcomes attractive to the parties involved.[27]

Regulators therefore restrict who may use the formal methods. In Australia, the FSVM must only be used by a professional engineer or other suitably qualified person recognised as competent in fire safety engineering.[28] C/VM2 is intended for professional fire engineers who are proficient in fire engineering modelling methods.[29] The IFEG describe third-party review by an independent peer or specialist, including check calculations, as a constructive way to support approval.[30]

A performance-based design is specific to its building, occupants and site. The IFEG call this both a strength and a weakness. It allows the fire safety system best suited to the building, but changes to the building, its occupants or its site may require a new evaluation.[31] Such a re-evaluation might not have been needed if the broader DTS provisions had been followed.[31]

Limits and criticism

The main weakness is the lack of quantified targets. The IFEG note that the level of safety intended by the Australian building code is not stated explicitly, so acceptance criteria must be developed for each design.[6] Because the link between criteria and performance requirements is a matter of engineering judgement, it varies between practitioners and projects. Involving all stakeholders reduces this variation.[6] The Australian handbook calls unquantified performance requirements a recognised limitation of performance-based codes and a barrier to their use.[32]

The Netherlands faces the same problem. Introduction to Fire Safety Engineering states that Dutch regulations do not lay down how many casualties are acceptable or how large the risk of fire spread to a neighbouring plot may be.[33] There are also no risk-based limit values, and the limits in the rule-based approach cannot be translated into them unambiguously.[22] Benchmarks themselves can be weak: the commentary to C/VM2 notes that many values in international codes are commonly accepted but have no technical basis.[34]

Tools and data are a further limit. The IFEG were deliberately written as guidelines rather than as a mandatory code, because fire engineering was judged to lack the necessary validated tools and data.[35] Fire engineering designs therefore rely heavily on engineering judgement, and approving authorities need to understand the process to assess them.[35]

See also

Notes

  1. ↑ 1.0 1.1 1.2 1.3 Australian Building Codes Board (2020b), p. 12.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 National Research Council of Canada et al. (2005), p. 1.2-21.
  3. ↑ 3.0 3.1 3.2 Australian Building Codes Board (2020b), p. 13.
  4. ↑ 4.0 4.1 4.2 National Research Council of Canada et al. (2005), p. 0.2-1 (Part 0, Australia).
  5. ↑ 5.0 5.1 5.2 5.3 5.4 National Research Council of Canada et al. (2005), p. 1.2-2.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 National Research Council of Canada et al. (2005), p. 0.2-3 (Part 0, Australia).
  7. ↑ 7.0 7.1 7.2 7.3 Van Rossum (2027), §2.1.
  8. ↑ National Research Council of Canada et al. (2005), p. 0.2-2 (Part 0, Australia).
  9. ↑ 9.0 9.1 Australian Building Codes Board (2020b), p. 16.
  10. ↑ Ministry of Business, Innovation and Employment (2025b), p. 2.
  11. ↑ Van Rossum (2027), §1.
  12. ↑ 12.0 12.1 National Research Council of Canada et al. (2005), p. 0.3-3 (Part 0, Australia).
  13. ↑ 13.0 13.1 Van Rossum (2027), §1.5.
  14. ↑ 14.0 14.1 14.2 Ministry of Business, Innovation and Employment (2013), p. 11.
  15. ↑ National Research Council of Canada et al. (2005), p. 1.1-2.
  16. ↑ 16.0 16.1 National Research Council of Canada et al. (2005), p. 1.2-32.
  17. ↑ National Research Council of Canada et al. (2005), p. 1.2-29.
  18. ↑ 18.0 18.1 Australian Building Codes Board (2020b), p. 125.
  19. ↑ Ministry of Business, Innovation and Employment (2025b), p. 9.
  20. ↑ 20.0 20.1 20.2 Australian Building Codes Board (2020b), p. 46.
  21. ↑ 21.0 21.1 21.2 National Research Council of Canada et al. (2005), p. 1.2-22.
  22. ↑ 22.0 22.1 Van Rossum (2027), §1.4.
  23. ↑ 23.0 23.1 23.2 National Research Council of Canada et al. (2005), p. 1.2-25.
  24. ↑ 24.0 24.1 Van Rossum (2027), §7.1.
  25. ↑ 25.0 25.1 25.2 National Research Council of Canada et al. (2005), p. 1.2-26.
  26. ↑ National Research Council of Canada et al. (2005), p. 1.2-24.
  27. ↑ Van Rossum (2027), §2.2.
  28. ↑ Australian Building Codes Board (2020b), p. 6.
  29. ↑ Ministry of Business, Innovation and Employment (2025b), p. 7.
  30. ↑ National Research Council of Canada et al. (2005), p. 0.3-8 (Part 0, Australia).
  31. ↑ 31.0 31.1 National Research Council of Canada et al. (2005), p. 0.3-7 (Part 0, Australia).
  32. ↑ Australian Building Codes Board (2020b), p. 14.
  33. ↑ Van Rossum (2027), §1.2.
  34. ↑ Ministry of Business, Innovation and Employment (2013), p. 12.
  35. ↑ 35.0 35.1 National Research Council of Canada et al. (2005), p. 0.1-2 (Part 0, Australia).

References

  • Australian Building Codes Board. (2020b). Handbook: Fire Safety Verification Method (Print version 1.1).
  • Ministry of Business, Innovation and Employment. (2013). Commentary for Building Code clauses C1–C6 and Verification Method C/VM2.
  • Ministry of Business, Innovation and Employment. (2025b). Verification Method C/VM2: Framework for fire safety design (2nd ed.).
  • National Research Council of Canada, International Code Council, Department of Building and Housing, & Australian Building Codes Board. (2005). International fire engineering guidelines (2005 ed.). Australian Building Codes Board.
  • Van Rossum, E. (2027). Introduction to Fire Safety Engineering. Fire Safety Academy.
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