NCC Tutor lesson - Understanding the performance-based code

Slide 1:

Welcome to Understanding the performance-based code.

Slide 2:

The focus of this presentation is the performance-based nature of the NCC, and what this means for compliance with the NCC.

Slide 3:

This is what you will learn about in this presentation.

What ‘performance-based’ means. Why we have a performance-based code. Elements of the performance-based code Understanding Performance Requirements. Deemed-to-Satisfy Solutions. Performance Solutions. Assessment Methods.

Slide 4:

What does ‘performance-based’ mean?

As a performance-based code, the NCC Performance Requirements represent the mandatory compliance level of performance that a building must achieve, across many different aspects, such as structural integrity, fire safety, health and amenity, access and egress etc. Buildings must comply with these requirements.

Performance Requirements specify a level to which some aspect of the building design or construction must perform in order to be compliant. For example the building structure must be able to resist winds up to a certain force. The building envelope must minimise energy use to retain a comfortable temperature for the climate in which it is built. Building elements must resist the passage of smoke, heat and gases for a minimum period of time so that people can evacuate in a fire.

Note that the Governing Requirements of the NCC must also be satisfied in order to comply with the NCC. These are found in Section A of all volumes of the NCC.

The NCC doesn’t specify how each building has to comply with the relevant requirements. The NCC does allows flexibility in how a building complies with the Performance Requirements.

It is up to the building designer or builder and other relevant stakeholders to propose how they will meet the relevant Performance Requirements for each particular building. This is the compliance solution for the building.

So, for example, the NCC doesn’t say that any particular material must be used for the walls in a building. It says that the materials used, and the way that they are used, must meet certain performance standards (for example, in terms of strength, fire resistance, noise transmission, energy efficiency) and then the designer or builder can (theoretically) use any material that meets the required performance standards.

There are 3 options for different types of compliance solutions.

A Deemed-to-Satisfy (DTS) Solution uses specified ways of meeting the Performance Requirements. These are included in the NCC as DTS Provisions.  In the law, to “deem” means to consider something as having certain characteristics.

So, if a DTS Solution is used then it is automatically considered to meet the Performance Requirements. Note that it might be necessary to do testing during construction to demonstrate that a DTS Solution has been installed correctly and therefore is achieving the required performance.

The DTS Provisions make use of well-known, established building and construction techniques/practices, and/or specify referenced documents, such as Australian Standards. This means that if the specified construction method is used, or construction is undertaken in compliance with the referenced Standard, then the building is deemed to comply with the Performance Requirements.

A Performance Solution is an another method of complying with the Performance Requirements, other than by a Deemed-to-Satisfy Solution. So, if the designer/builder wants to do something different with their building, theoretically there are no restrictions on what solution they choose to design, e.g. what materials they can use and what building techniques they use. The resulting building just needs to meet all of the relevant Performance Requirements.

It is also possible to use a combination of DTS Solution and a Performance Solution. This means that the designer/builder might use a DTS Solution to achieve some Performance Requirements or some aspect of a Performance Requirement, but will design a Performance Solution to meet other Performance Requirements or other aspects of a Performance Requirement.

When using a Performance Solution, the designer must demonstrate how the Performance Solution complies with the relevant Performance Requirements, through the use of Assessment Methods.

Assessment Methods are methods that can be used to demonstrate that a Performance Solution or DTS Solution complies with the Performance Requirements. The 4 possible assessment methods are Evidence of suitability, Verification Methods, Expert Judgement, Comparison with DTS Provisions.

An appropriate authority is required to review the proposed Compliance Solution for each building to determine if it complies with the relevant Performance Requirements. 

Slide 5:

Why do we have a performance-based code?

In the past, Australia’s building and plumbing codes were prescriptive, rather than performance-based. This means that they prescribed (i.e. mandated precisely) When something must be done, what must be done, exactly how it must be done.

This meant that when a designer or builder wanted to do something different or innovative, they had to seek approval from a specialist tribunal or court. This could take a long time and add a significant cost to the project. 

This lack of flexibility made it hard to innovate and improve building design, practices and materials, delayed projects and increased costs.

For example, if a builder wanted to use a new product with better thermal properties or a new building system, they would have to seek a variation to the code, which would take time and cost money. If this variation was not granted, they would then have to lodge an objection or appeal the decision, which would mean more money spent and more time lost.

Instead, the performance-based nature of the NCC means that as long as a designer or builder can demonstrate that the design, material or building system meets the relevant Performance Requirement/s in the NCC, they should be given approval to use it.

Many of the newer innovations in building design, construction and materials would have been difficult, time-consuming and expensive to achieve under a prescriptive code. For example building a house that complies with the Swiss “Passiv Haus” energy efficiency standard, using unusual building materials such as 3-D printed building components, using some modular building design and construction systems, creating a building from unusual items such as unwanted shipping containers.

Slide 6:

Match each term to the closest explanation…

A prescriptive approach that is deemed to meet a Performance Requirement equals DTS Solution

The level to which a building, building element or plumbing element must perform to be compliant equals Performance Requirement 

A non-prescriptive approach to complying with a Performance Requirement equals Performance Solution

Any kind of approach to complying with the Performance Requirement/s equals Compliance Solution

A way of demonstrating a solution meets the Performance Requirement/s = Assessment Method

Slide 7:

Understanding Performance Requirements

Example 1: NCC Volume One, F4P5 Construction of sanitary compartments to allow removal of unconscious people.

Part F4 Sanitary and other facilities. Must be able to access any sanitary compartment to remove an unconscious person. One of 6 Performance Requirements in this Part. Qualitative – “with sufficient space or other means”.

For example, the compartment could be built so that the door can quickly be completely removed to allow the removal of an unconscious person. In this case, the space in the compartment would be less of an issue, because removing the door allows access and removal.

Example 2: NCC Volume One, B1P3 Glass installations at risk of human impact

Section B Structural. Design glass at risk of impact from a person provides at adequate level of safety. One of 4 performance requirements in sections. Qualitative – “not likely to cause”, “reasonably foreseeable”, “reduce the likelihood”. Consider each factor individually when developing a compliance solution.

For example, a sliding glass door is likely to require some form of marking to identify it, to prevent someone walking through it.

Example 3: NCC Volume Two, H7P5 Buildings in bushfire prone areas

Part H7 Ancillary provisions and additional construction requirements.

Design and construct Class 1 buildings and associated structures to reduce the risk of ignition during a bushfire.

Limited to buildings constructed in designated bushfire prone areas.

Note that that Tasmania has a variation to this Performance Requirement. 

Example 4: NCC Volume Two H2P1 Rainwater management

Part H2 Damp and weatherproofing.

Design and construct the building and drainage to prevent surface water from entering the building or damaging/creating a nuisance for another property.

Limited – doesn’t apply to some Class 10 buildings.

Quantitative – “annual exceedance probability of 5%”, “annual exceedance probability of 1%”.

Specifies the intensity of rainfall which the building and drainage must be designed for. A designer must use this specified rainfall measurement as a minimum requirement, and design to meet this. How they design the building to meet this requirement is flexible.

For example, the building could be designed with a drainage system that is big enough to remove the volume of water expected with an annual exceedance probability of 5% without causing flooding to a nearby property. Or it could be designed to capture storm water from the building’s roof with tanks that are big enough to hold quantity of water expected with an annual exceedance probability of 5% and a smaller drainage system to take away any excess.  Or, in some cases, such as a house on a large property could direct water to a wetland area which would prevent the water from exiting to another property.

Example 5: NCC Volume Three, B1P1 Cold water supply

Section B Water Services. Part B1 Cold water services. Cold water supplied to a building must be connected to a supply that delivers water suitable for drinking. Limited – applies only to water supplied for eating, drinking, food preparation, dishwashing and personal care.

So, for example, the water supply for flushing toilets or for an evaporative cooler does not need to be from a drinking water supply, because this water is not intended for any of the uses listed.

Example 6: NCC Volume Three, E1P1 Facilities for people with disability

Section E Facilities. Part E1 Facilities. Taps and other controls must have features that allow them to be used by people with a disability. Single Performance Requirement in this Part. Qualitative – “suitable for use”. An appropriate authority would determine what kind of taps and other controls would be considered suitable for use. For example, in some circumstances voice or motion activated taps could be considered suitable.

Slide 8:

Interpreting Performance Requirements

Question 1: What is required by this Performance Requirement?

The Performance Requirement requires 2 different things: 1. That some disabled car parking spaces are provided. 2. That those spaces are clearly designated so that people who are entitled to use them can find them.

Question 2: What limitation applies to this Performance Requirement?

The Performance Requirement is limited, so that it doesn’t apply in the circumstances listed, i.e. when the building has a parking service, such as valet parking that you might find at a hotel or in a busy city paid carpark, When the building has no direct access to any carparking spaces for use by anyone.

Question 3: Is this Performance Requirement quantitative or qualitative?

The Performance Requirement is qualitative; it says you must provide disabled carparks “to the degree necessary, to give equitable access for carparking”.

In this case, a designer/builder can design in a certain number of spaces, and the appropriate authority would consider whether the proposed number of spaces was reasonable, given things like the size, purpose, location and likely use of the building.

Someone could challenge the planned design of a building on the basis that the number of disabled carparks was not sufficient. (That someone could be a person with a disability who would be a user of the finished building, or a disability advocacy group.)

If this Performance Requirement was quantitative, it might have specified a certain number of disabled car parks as being required, depending on something like the number of people expected to live, work or visit the building. 

Slide 9:

Understanding compliance solutions

A performance-based code aims to allow for flexibility in approaches, to satisfy the Performance Requirements.

So there are multiple ways to comply with relevant Performance Requirements in the NCC.

One way is to use the DTS Provisions which are documented within the NCC Volumes. The DTS Provisions are “deemed” to comply with the Performance Requirements. They are typically referred to as DTS Provisions. (“Deemed” is a legally precise word that essentially means “considered to be”.) 

The DTS Provisions generally involve building or installing an element in line with the requirements of an Australian Standard or a similar referenced document, or using a well-known, well-accepted practice. Typically reflect pretty standard ways of doing things that most designers, builders and plumbers will be aware of. Tend to reference known materials, techniques and processes. The DTS Provisions may provide a straightforward way to comply with the Performance Requirements. BUT, they have little flexibility and can limit innovation because they specify in detail how things need to be done.

When designers, builders or plumbers want to do something different, they often need to look beyond the DTS Solutions, to formulate a compliance solution especially designed for the particular building. This is known as a Performance Solution equals  a Compliance Solution that demonstrates how a particular building complies with the relevant Performance Requirements without using the DTS Provisions in the NCC. 

A Performance Solution can have many elements and can make use of a wide range of materials, techniques and processes, as long as it demonstrates clearly that these comply with the relevant Performance Requirements. So, Performance Solutions can provide the flexibility and innovation that a performance-based code seeks to allow.

However, creating a unique Performance Solution for every single aspect of a project, i.e. for every single applicable Performance Requirement, may be time consuming. Often, a designer, builder or plumber will use DTS Solutions and Performance Solutions, in combination. 

For example, they might use the DTS Provisions for straightforward aspects of the build which are to be completed using standard materials and building processes. But they would use a Performance Solution for other aspects where they want to use non-standard materials or processes or achieve an unusual result in terms of either the aesthetics, the function or the performance of the building. 

This could mean using a DTS Solution to comply with one aspect of an individual Performance Requirement and a Performance Solution to comply with another aspect of the same Performance Requirement.

Using a DTS Solution to meet some Performance Requirements in one Part and Performance Solutions for other Performance Requirements in the same Part.

Using a DTS Solution to meet all of the Performance Requirements in one or more Parts of the relevant volume, and using a Performance Solution to meet all the Performance Requirements in other Parts of the relevant volume.

Slide 10:

Interpreting DTS Provisions

Question 1: In what different ways can a sanitary compartment be designed to allow for an unconscious person to be removed?

Question 2: How high do the door and partitions of a sanitary compartment need to be?

Question 3: The single sex bathrooms in a high-tech office are designed with floor to ceiling partitions and full height doors that will slide up into the roof. Does this design meet the DTS Provisions?

The excerpt shows the DTS Provisions related to one of the Performance Requirement examples included earlier in the module. That Performance Requirement was F4P5 Construction of sanitary compartments to allow removal of unconscious people. 

The DTS Provisions here show one, reasonably straightforward, method for complying with this Performance Requirement related to 1. The heights of doors and partitions when there are adjacent compartments, e.g. multiple toilet stalls. That is, the provisions relate to privacy. 2. Mechanisms that allow for access to remove an unconscious person from a sanitary compartment. 3. In terms of access to remove an unconscious person, if a building design complies with these DTS Provisions, then it complies with the Performance Requirements. This means that a design complies with the Performance Requirements if it is built with doors that open outwards, OR slide open, OR can be easily removed from the outside, OR have the required amount of clear space around them.

Theoretically, a designer or builder could come up with other options to meet the Performance Requirements, for example doors that slid away into the floor or ceiling. 

A designer or builder can exceed these minimum requirements also. For example, even though the partitions and doors in single sex bathrooms only need to be a minimum of 1.8 m high, they can be designed to be full height (commonly 2.4 m).

Note that there is a clause (c) which describes how to comply with the Performance Requirements for an early childhood centre. 

Slide 11:

Understanding Performance Solutions. Any compliance solution that doesn’t make use of the DTS Provisions in the NCC is a Performance Solution.

Allowing Performance Solutions provides flexibility to do things differently – to use different materials, methods and techniques, and potentially to innovate, save money and improve the constructability of a building.

However, a Performance Solution must provide at least the minimum level required by the relevant Performance Requirements. (It can do better also.)

A2G2 in the NCC states that a Performance Solution will only comply with the NCC when the Assessment Methods used demonstrate compliance with Performance Requirements. This means that a designer or builder must demonstrate that the Performance Solution complies with the relevant Performance Requirements using one of the four Assessment Methods described in A2G2 of the NCC. Note that these Assessment Methods are discussed on the next slide.

Designers and builders must ensure that an appropriate Assessment Method is used.

How do you know which Assessment Methods are appropriate? It is a good idea to discuss this with the relevant approval authority before you take the time to develop and document a detailed Performance Solution.

Slide 12:

Understanding Assessment Methods

Whether you choose to use a DTS Solution or a Performance Solution or a combination of them, you need to provide some evidence that the proposed solution complies with the Performance Requirements.

The NCC recognises four valid ways of assessing possible compliance solutions, which are shown on the slide on Layer 2.

All 4 methods can be used to demonstrate compliance with the Performance Requirements when you are using a Performance Solution. 

Evidence of suitability and Expert Judgement can be used when you are using a DTS Solution.

Sometimes, the use of a particular Assessment Method will be straight forward, but in other cases it will require use of consultants and testing. 

By understanding the possibilities and requirements of the different Assessment Methods, you will be able to better judge when it makes sense to use each one, and how best to make your case for a Performance Solution.

Verification Method: A Verification Method (VM) is a test, inspection, calculation, or other method that determines whether a Performance Solution complies with the relevant Performance Requirements.

Each NCC Volume lists acceptable Verification Methods for different Performance Requirements. 

But not every Performance Requirement has acceptable VMs in the NCC. 

In formulating a Performance Solution using a VM, a designer can choose to use a VM that is listed in the NCC, or they can use another method that is not listed in the NCC.

For example, Volume One, lists D1V1 as a VM for wire barriers, specifically compliance with Performance Requirements D1P3(2)(c) and (d). E4V1 as a VM for emergency lighting, specifically compliance with Performance Requirement E4P1. 

Other VMs that could be used to demonstrate compliance with the relevant Performance Requirements include calculations, analytical methods or mathematical models, tests, using a testing procedure, either  on site or in a laboratory, inspection report, any other acceptable method.

The final decision on whether any Verification Method is acceptable resides with the appropriate authority, used for Performance Solutions only.

Evidence of suitability: Concept is introduced in Part A2, but details of acceptable evidence is found in Part A5 Documentation of design and construction in all NCC volumes.

The same evidence of suitability is acceptable for Volumes One and Two (the BCA), but there are different evidence requirements for Volume Three (the PCA).

Volumes One and Two: Documentary evidence may come from an appropriately qualified person who may provide test results or relevant information demonstrating the suitability of the building solution.

A report from a professional engineer or recognised expert, certificate from a certification body, report from an Accredited Testing Laboratory.

Volume Three: Volume Three refers to a mandatory plumbing product certification scheme, known as the WaterMark Certification Scheme. 

A wide variety of plumbing products must be certified under the WaterMark Scheme. This certification comes in the form of a ‘WaterMark Licence’. (The WaterMark Certification Scheme is discussed in more detail in the module Using NCC Volume Three.)

For any material or product not subject to the WaterMark Certification Scheme, documentary evidence may come from a certification body or Accredited Testing Laboratory who may provide test results or relevant information demonstrating the suitability of the plumbing solution. It may also be subject to a risk assessment in accordance with the WaterMark Scheme Rules.

A report/certificate from a professional engineer, recognised expert or other appropriately qualified person may also be put forward as documentary evidence. 

The term Accredited Testing Laboratory is defined in the NCC. If the trainees are interested, then get them to look up the definition. The NCC also allows the option to provide any other documentary evidence that may demonstrate the suitability of the solution. 

The form of evidence used must be appropriate to the use of the material, building or plumbing product, form of construction or design it relates to. 

The final decision on whether a document or expert opinion is accepted resides with the appropriate authority. Used for both Performance Solutions and DTS Solutions.

Comparison with DTS Provisions: A Performance Solution can be compared to a current DTS Provision to highlight how it will achieve compliance with the Performance Requirements. 

In comparison to the other Assessment Methods, this may be a more straightforward methodology, as a benchmark has been set against which the proposed solution can be compared.

As with other Assessment Methods, the final decision on whether a comparison with DTS Provisions is acceptable resides with the appropriate authority.

Used for Performance Solutions only. (Obviously, it doesn’t make sense to compare a DTS Solution with itself.)

Expert Judgement: In some situations where a unique design solution is proposed, an Expert Judgement may be required. This is especially the case in new, innovative approaches where there is little past history, documentation or the ability to physically test. 

The NCC defines ‘Expert Judgement’ as the judgement of an expert who has the qualifications and experience to determine whether a Performance Solution or DTS Solution complies with the Performance Requirements.

This is a broad definition and should be applied judiciously. 

The expert needs to have a demonstrated knowledge of the technical issues involved, supported by peer recognition.

The use of Expert Judgement is very much dependent upon the situation.

As with other Assessment Methods, the final decision on whether an Expert Judgement is acceptable resides with the appropriate authority. 

Used for Performance Solutions and DTS Solutions.

Slide 13:

Developing a compliance solution

Performance Requirements, See F3P1 Weatherproofing. The roof must prevent the penetration of water that could cause (a) and (b), applies to the roof of all buildings of all classes, doesn’t say how compliance must be achieved, use a DTS Solution, a Performance Solution or a combination of both. 

Performance Solution. A sustainability conscious client wats to use an innovative type of roofing sheet that is 3D printed from recycled plastics at the construction site. DTS Provision, F3D2 Roof coverings, doesn’t apply. A Performance Solution is required, must demonstrate the proposed roof covering will prevent the penetration of water as required by Performance Requirement F3P1, i.e. that the roof will perform as required.

Consultation with relevant stakeholders and appropriate Assessment methods must be used to demonstrate compliance. Approving Authority must be satisfied that the proposed Performance Solution will comply. 

Deemed-to-satisfy solution. See F3D2 Roof coverings. References a number of documents that address acceptable methods of preventing water from penetrating through a roof depending on the type of roof installed.

Therefore, if a roof covering is installed in accordance with F3D2, it is deemed to be acceptable and to comply with F3P1

For example. A metal sheet roof that complies wth AS 1562.1 Design and installation of sheet roof and wall cladding.

Assessment Methods. Performance Solution. 

For the Performance Solution, the builder, engineer and appropriate authority discuss and agrees to the Performance Solution, which is supported by waterproofing testing of a sample of the 3D printed sheets by an Accredited Testing Laboratory, who provides a report documenting Evidence of Suitability. An Expert Judgement from a professional engineer as a recongised expert to demonstrate that the roof covering and construction together will satisfy the Performance Requirement. Post-installation inspection by a building certifier certifies the 3D printed roof sheeting has been installed in a way that meets requirements 

DTS Solution. For a DTS Solution, the builder purchases and installs metal sheet roofing that complies with AS 1562.1 (2018) Design and installation of sheet roof and wall cladding. 

Because the metal roof requires sarking to be compliant, purchases and installs a sarking product that complies with AS/NZS 4200 Parts 1 and 2 Pliable building membranes and underlays. 

Organises for inspection by a building certifier certifies both the roofing and sarking products and their installation comply with the relevant Standards 

Combined Solution.  

For a combined DTS and Performance Solution, the builder provides evidence of compliance for the innovative 3D printed roofing product e.g. agrees to the use of particular Assessment Methods with the approving authority.

Organises testing by Accredited Testing Laboratory to provide Evidence of Suitability. Obtains an Expert Judgement from a professional engineer.  

Purchases a compliant sarking product and installs it in compliance with the appropriate Standard. Organises for post-installation inspection and certification of both the roof and the sarking by a building certifier. 

Slide 14:

The NCC is described as a performance-based code because it a) Mandates exactly when, how, where and why buildings and building elements must perform. b) Sets minimum requirements for how buildings and building elements perform and allows designers and buildings to choose the best way of achieving them. C)Is based on the performance required to keep people and buildings safe.

If you answered (b) - Yes, that’s right. The NCC establishes the minimum Performance Requirements for buildings and building elements, but allows designers, builders and plumbers to choose how to achieve them for each individual building.

Slide 15:

Which of the following is a valid approach to meeting the NCC Performance Requirements?

DTS Solution, Performance Solution, DTS Solution and/or Performance Solution, Assessment Method.

If you answered DTS Solution and/or Performance Solution - Yes, that’s right. You can use either of these methods or a combination of them.

Slide 16 

Label the diagram below. 

The correct labels are Compliance Level – Performance Requirements, Compliance Solutions – Performance Solution and/or Deemed-to-Satisfy Solution, Evidence of Compliance – Assessment Methods.

Slide 17

Match the assessment methods to the type of compliance solutions they can be used with all Assessment Methods can be used with a Performance Solution. Evidence of suitability and Expert Judgement can be used with a DTS Solution.

Slide 18 

Summary. The performance-based code establishes the performance criteria that a building and its elements must meet. Provides options for how this is achieved, ensures buildings and building elements perform as needed, allows flexibility, allows innovation, Reduces costs.

Performance Requirements specify how a building and its elements must perform. Compliance solutions describe how a building and its elements will meet the Performance Requirements.

Slide 19

Key points. Three options for compliance solutions. Deemed-to-Satisfy Solution, Performance Solution, Combination of both.

Deemed-to-Satisfy (DTS) Solutions may use referenced documents or established building practices. Straightforward way of complying but may lack flexibility.

Performance Solutions allow for flexibility and innovation, must demonstrate that the solution meets the Performance Requirements.

Assessment Methods are used to demonstrate compliance. Verification Method, Expert Judgement, Evidence of suitability, Comparison with DTS Provisions.

Slide 20:

Thank you for your time. That brings our presentation on understanding the performance-based code to a close. If you’d like more information please visit abcb.gov.au