NCC Tutor lesson - Understanding the performance-based code

NCC Tutor Series 

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

This module is best viewed with a copy of the NCC on hand – to access the NCC, visit abcb.gov.au and register or log in to freely access it. 

Slide 1 

In this presentation you will learn: 

• what ‘performance-based’ means 

• why we have a performance-based code, and 

• elements of the performance-based code 

We will also examine: 

• Performance Requirements 

• Deemed-to-Satisfy Solutions 

• Performance Solutions, and  

• Assessment Methods. 

Slide 2 

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 envelope must minimise energy use to retain a comfortable temperature for the climate in which it is built 

• and 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 Volumes One and Three and Section 1 of Volume Two.  

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 in which  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 three options for different types of Compliance Solutions. 

A Deemed-to-Satisfy or 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 and practices and or specify referenced documents, such as the 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 or 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 or builder might use a DTS Solution to achieve some of the 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, throughout the Assessment Methods. 

Assessment Methods are methods that can be used to demonstrate that a Performance Solution or Deemed-to-Satisfy Solution complies with the Performance Requirements. The four possible assessment methods are: 

• Evidence of suitability 

• 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 3 

In the past, Australia’s building and plumbing codes were prescriptive, rather than performance-based. That 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 significantly to the cost of 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 out 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 and more time being 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, then 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, or  

• using unusual building materials such as 3-D printed building components 

• or perhaps, using some modular building design and construction systems 

• or maybe creating a building from unusual items such as unwanted shipping containers. 

Slide 4 

Let’s test your knowledge of these terms. 

• Performance Solution 

• Assessment Method 

• Compliance Solution 

• Performance Requirements 

• DTS Solution. 

Definitions:

• A prescriptive approach that is deemed to meet a Performance Requirement
• The level to which a building, building element or plumbing element must perform to be compliant
• A non-prescriptive approach to complying with a Performance Requirement
• Any kind of approach to complying with the Performance Requirements
• A way of demonstrating that a solution meets the Performance Requirements.

Match each term to the closest definition 

• A prescriptive approach that is deemed to meet a Performance Requirement: Is a DTS Solution
• The level to which a building, building element or plumbing element must perform to be compliant: Is a Performance Requirements
• A non-prescriptive approach to complying with a Performance Requirement: Is a  Performance Solution
• Any kind of approach to complying with the Performance Requirements: Is a Compliance Solution
• A way of demonstrating that a solution meets the Performance Requirements: Is an Assessment Method

Slide 5 

Understanding performance requirements.  

In a moment we’re going to look at some examples of different Performance Requirements. Firstly, let’s consider some key terms and language used in different Performance Requirements and whether a Performance Requirement is; qualitative or quantitative. 

When you first look at a Performance Requirement, the obvious thing to consider is; 

What performance is required?  

How must the building or and element of the building perform for its intended purpose? 

Is the Performance Requirement qualitative or quantitative?  

• If it specifies an attribute or quality that it must be achieved then it is qualitative. 

• If it asks for a specified value or absolute measure of performance to be achieved it is quantitative. 

Are there any Limitations on the application of the Performance Requirement?  

• For example, does it only apply to a particular Class or Classes of building?  

• Does it only apply under other criteria, such as if the building has more than a certain number of storeys (i.e. rise in storeys, in NCC terminology) or has a floor area greater than a specified figure? 

Some terms used in Performance Requirements may signal some flexibility in the application of the Performance Requirement. For example;  

• “sufficient”, “to the degree necessary”, “suitable” and “appropriate to” 

• This gives the building designer some flexibility when designing a building suitable for it’s intended purpose and particular circumstances.  

• It also gives the Approval Authority flexibility to decide on the degree of compliance necessary.  

So let’s now look at some examples here and see if we can interpret them.  

Example 1: NCC Volume One, FP2.5 Construction of sanitary compartments to allow removal of unconscious people. 

So in which Part is this Performance Requirement found? 

What is the performance required? 

Is the Performance Requirement qualitative or quantitative? 

FP2.5 is found in Part F2 Sanitary and other facilities. The Performance Requirement is qualitative. 

Note the words, 'with sufficient space or other means', performance required is a sanitary compartment must be constructed in a way to ensure that access can be gained to remove unconscious people from inside the sanitary compartment. So what this means is that, 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. 

Let’s look at Example 3: NCC Volume Two, P2.75 Buildings in bushfire prone areas 

What do you think? 

In which Part is this Performance Requirement found? 

What is the performance required? 

And is the Performance Requirement qualitative or quantitative? 

This Performance Requirement is found in Section 2 Performance Provisions and is limited to buildings in designated bushfire prone areas. It is qualitative in nature notice the words “to the degree necessary”, and “appropriate to”. The appropriate authorities would need to determine to what degree each building needed to be protected from ignition. 

For example, a building in a semi-rural setting, with a town water supply and close to a fire-fighting service, might be judged as needing less protection than a building in an isolated rural, bush setting with no guaranteed water supply or nearby fire-fighting service.  

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

Now our last one. Example 6: NCC Volume Three, EP1.1 Facilities for people with a disability 

In which Part is this Performance Requirement found? 

What performance is required? 

Is this Performance Requirement qualitative or quantitative? 

This Performance Requirement is found in Section E Facilities, Part E1 Facilities 

The performance required is that taps and other controls must have features that allow them to be used by people with a disability. 

This Performance Requirement is qualitative. Note the words “suitable for use”. 

An appropriate authority would need 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 6 

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 Deemed-to-Satisfy Provisions which are documented within the NCC volumes. The Deemed-to-Satisfy Provisions are “deemed” to comply with the Performance Requirements. They are typically referred to as DTS Provisions.  

The DTS Provisions: 

• Generally involve building or installing an element in line with the requirements of an Australian Standard or similar referenced document, or using a well-known, well-accepted practice.  

• DTS provisions typically reflect pretty standard ways of doing things that most designers, builders and plumbers will be aware of.  

• They also 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 provisions, to formulate a compliance solution especially designed for that particular building. This is known as a Performance Solution , it’s 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 is demonstrated 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 solutions for straightforward aspects of the build which are to be completed using standard materials and standard 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. 

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

• Or perhaps 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 7 

Interpreting the DTS Provisions.  

The excerpt shows the DTS Provisions related to one of the Performance Requirement examples that were included earlier. That Performance Requirement was FP2.5 Construction of sanitary compartments to allow removal of unconscious people.  

The DTS Provisions here show one, reasonably straightforward method of complying with this Performance Requirement: 

• The heights of doors and partitions when there are adjacent compartments, for example, multiple toilet stalls. That is, the provisions relate to privacy. 

• Mechanisms that allow for access to remove an unconscious person from a sanitary compartment. 

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. That 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 be 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 8 

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 also do better. 

A2.2 in the NCC states that a Performance Solution will only comply with the NCC when the Assessment Methods used demonstrate compliance with Performance Requirements. That 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 Part A2.2 of the NCC. We’ll discuss Assessment Methods later in this presentation. 

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 9 

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

Slide 10 

The NCC recognises four valid ways of assessing possible compliance solutions. 

All four 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 an acceptable Verification Method in the NCC.  

In formulating a Performance Solution using a Verification Method, a designer can choose to use a Verification Method that is listed in the NCC, or they can use another method that is not listed in the NCC. For example, NCC Volume One, lists: 

• DV1 as a Verification Method for wire barriers, specifically for compliance with Performance Requirements DP3(f) and DP3(g). 

• EV4.1 as a VM for emergency lighting, specifically for compliance with Performance Requirement EP4.1.  

Other Verification Methods 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 reports, or 

• Any other acceptable method. 

The final decision on whether any Verification Method is acceptable resides with the appropriate authority. Don’t forget, this is used for Performance Solutions only. 

The next is evidence of suitability 

This 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 itself), but there are different evidence requirements for Volume Three (the PCA). 

For Volumes One and Two Documentary evidence may come from an appropriately qualified person who may produce test results or relevant information demonstrating suitability of the building or plumbing solution. This is often: 

• a report from a professional engineer or recognised expert 

• a certificate from a certification body, or 

• a report from an Accredited Testing Laboratory. 

In 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’.  

For any materials or products 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 or 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.  

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.  

• Don’t forget, this is used for both Performance Solutions and DTS Solutions. 

The next is comparison with DTS Provisions. A Performance Solution can be compared to a current Deemed-to-Satisfy 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. 

Keep in mind this is used for Performance Solutions only.  

The last is Expert Judgement. In some situations where a unique design solution is proposed, an Expert Judgment 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 Deemed-to-Satisfy 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 on the situation. 

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

Keep in mind it’s used for both Performance Solutions and DTS Solutions. 

Slide 11 

To ensure compliance we need to meet the Performance Requirements. When we look at the Performance Requirements using this example we’re looking at FP1.4 Weatherproofing and in this example a roof and an external wall including openings, around windows and doors must prevent the penetration of water that could cause unhealthy and dangerous conditions or loss of amenity for the occupants and undue dampness or deterioration of building elements.  

This applies to the roof of all buildings of all classes. Although it doesn't say how compliance must be achieved. To do so we can look at a number of different Compliance Solutions. 

We could use either a Performance Solution, a Deemed-to-Satisfy Solution or DTS solution, or a combination of both. 

When we look at the Performance Solution, we can identify here sustainability conscious client wants to use an innovative type of roofing sheet that can be 3D printed from recycled plastics at the construction site, DTS Provision F1.5 Roof coverings doesn't apply, therefore a Performance Solution is required. 

We must demonstrate that the proposed roof covering will prevent the penetration of water as required by the Performance Requirements FP1.4 i.e that the roof will perform as required. We need to consult with relevant stakeholders and appropriate Assessment Methods must be used to demonstrate compliance. 

The approving authority must be satisfied that the proposed Performance Solution will comply. 

If we looked at the Deemed-to-Satisfy Solution, we can see here that in F1.5 Roof coverings, a roof must be covered with and gives the specific examples. 

This particular Clause 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 F1.5 it is deemed to have been acceptable and to comply with FP1.4. 

For example, a metal sheet roof that complies with AS 1562.1 Design and Installation of Sheet Roof and Wall Cladding. 

When we look at the Assessment Methods, we've got Assessment Methods that apply to a Performance Solution. For the Performance Solution, the builder, engineer and appropriate authority discusses and agrees to the Performance Solution which is supported by water proof testing of a sample of the 3D printed sheets by an accredited testing laboratory who provide a report documenting evidence of suitability, could be an expert judgement from a professional engineer as a recognised expert to demonstrate that the roof covering and construction together will satisfy the Performance Requirement, could be also that its post installation inspection is done by building certifier to certify that the 3D printed roof sheeting has been installed in a way that meets requirements. 

If we're looking at the DTS Solution, the builder purchases, installs metal sheet roofing that complies with AS 1562.1-1992 Design and installation of sheet roof and wall cladding. Because the metal roof requires sarking to be compliant, the builder also purchases and installs a sarking product that complies with AS/NZS 4200 Parts 1 and 2. They then organise for the inspection by building certifier to certify that both the roofing and the sarking products and their installation comply with the relevant standards. 

If we looked at a combined solution, combining both DTS and Performance Solution, the builder could 

. provide evidence of compliance for the any of the 3D printed roofing product, such as agrees to the use of a particular Assessment Method with the approving authority 

.  organises testing by an accredited testing laboratory to provide evidence of suitability 

. obtains an expert judgment from a professional engineer 

They could also purchase a compliant sarking product and install it in compliance with the appropriate standard and also organise for post installation inspection and certification of both the roof and the sarking by a building certifier. 

Slide 12 

Let’s test your knowledge with a few questions: 

The NCC is described as a performance-based code because it… 

• mandates exactly when, how, where and why buildings and building elements must perform 

• sets minimum requirements for how buildings and building elements perform and allows designers and builders to choose the best way of achieving them, or 

• is based on the performance required to keep people and buildings safe. 

Take a moment to consider your answer. 

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 13 

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

• DTS Solution 

• Performance Solution 

• DTS Solution and Performance Solution 

• Assessment Method 

Take a moment to consider your answer. 

Yes, that’s right. You can use either of these methods or a combination of the two. 

Slide 14 

Label the diagram below. Take a moment to consider what the missing words are. 

• Compliance Level: Performance Requirements
• Compliance Solutions: Performance Solutions and/or Deemed-to-Satisfy Solution
• Evidence of Compliance: Assessment Methods

Slide 15 

Match the assessment methods to the type of compliance solutions they can be used with… 

Assessment Methods

• Evidence of suitability
• Comparison with DTS solution
• Expert Judgement
• Verification Method

Compliance Solutions

• Performance Solution
• Deemed-to-Satisfy Solution

All Assessment Methods can be used with a Performance Solution. 

Evidence of suitability and Expert Judgement can be used with a DTS Solution. 

Slide 16 

The Key Points of this presentation are: There are three options for compliance solutions: 

• Deemed-to-Satisfy Solution 

• Performance Solution 

• Or a combination of the two 

Deemed-to-Satisfy (DTS) Solutions may use referenced documents or established building practices. They’re generally straightforward ways of complying but may lack flexibility. 

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

Assessment Methods are used to demonstrate compliance. These are:  

• Verification Method,  

• Expert Judgement,  

• Evidence of suitability, and  

• Comparison with DTS Provisions 

End of presentation 

This brings us to the end of the presentation.  

Thank you for viewing this NCC Tutor module. Check out the other NCC Tutor modules available to build your understanding of the NCC. 

[End of transcript]