National Construction Code – A Performance Based Code

Authored by Damon Stewart, Building Solutions Engineer at DDEG

The National Construction Code (NCC) is a Performance Based Code that sets the minimum required level for the safety, health, amenity, accessibility, and sustainability of certain buildings in Australia. Compliance with the NCC is achieved by complying with the Governing Requirements and the Performance Requirements of the NCC. Performance Requirements outline the minimum necessary standards different buildings or building elements must attain and are the only NCC technical provisions that must be satisfied.

Performance Requirements are satisfied by either a Performance Solution, a Deemed-to-Satisfy (DTS) Solution, or a combination of both. A Deemed-to-Satisfy Solution is achieved by following the appropriate Deemed-to-Satisfy Provisions in the NCC.?The Deemed-to-Satisfy Provisions are a prescriptive set of provisions that is generally seen as the basis upon which all buildings are designed and constructed to. However, there are misconceptions within the building and construction industry that the DTS Provisions are the best possible solution in every situation, and that practitioners need only to comply with the DTS Provisions (Heaton, 2018). However, strict compliance with DTS Provisions is not always achievable nor desirable for all buildings, due to factors including functionality, practicality, design constraints and cost.

A simple example of this is a rangehood installed in a commercial kitchen. A rangehood may reduce the head height clearance to below the 2.4m stipulated by the DTS Provisions, as it may be required to be installed at a height of 2.1m in order to adequately remove odours, heat and smoke from a kitchen. However, installing a rangehood at such a height does not mean that the performance of the kitchen is diminished, as the individuals within the kitchen will still be able to complete their tasks within this space. Nor does this mean that the height of the rangehood should be increased to comply with the DTS Provisions, as this may impact the functionality of the rangehood and cause a variety of other issues in the kitchen.

Furthermore, prescriptive building codes can often serve as a major barrier to innovation, preventing the development and introduction of improved or alternative products and construction methods (Greenwood, 2007), which can overall be damaging to the industry, and to society in the long run. Technological change can be difficult to predict, and is often far too swift for building regulations and legislation to keep up with. By focussing on the performance of a building, the industry can more readily take advantage of technology changes that were not envisaged when the regulations were drafted (The Centre For International Economics, 2012, December 4).

The limitations caused by prescriptive building codes gave rise to the introduction of Performance-based codes in Australia in 1996, after the industry came together in the late 1980s to request that governments introduce a performance-based code to facilitate the delivery of new buildings, construction techniques and products (Heaton, 2018). The introduction of a performance based Building Code of Australia (BCA) was designed to attain the following improvements of a revised building control industry:

• Introducing greater flexibility in building design;
• Improving the clarity of requirements in building approvals;
• Reducing the complexity of the Code, allowing a greater ease of use;
• Allowing easier application to renovation and refurbishment projects;
• Creating a greater responsiveness to innovation; and
• Introducing greater clarity of intent and consistency in scope?(Greenwood, 2007).

Although the NCC has been a Performance Based Code since 1996, in 2012 it was estimated that only 50 percent of the potential benefits of the national code and the performance-based standards had been realised (The Centre For International Economics, 2012, December 4). The Australian Building Codes Board (ABCB) is currently working to increase the competent use of the Performance Requirements in the NCC in order to support industry innovation via a four component initiative which includes:

• Education: The ABCB’s education initiative is helping to build industry capability to develop Performance Solutions by improving the understanding of the performance-based code.
• Strategic Review of Performance Requirements: The Performance Requirements are being reviewed systematically with the process aiming to improve clarity and objectivity in order to better describe the core components of building performance.
• Quantification: The ABCB are aiming to rigorously quantify requirements which will provide objective levels of performance for practitioners to target which will encourage both increased use of performance and competency when practitioners develop Performance Solutions.
• Collaboration with Industry: The ABCB is liaising with industry to gather perspectives on how the code could better encourage the competent use of performance?(Australian Building Codes Board, 2017).

On July 1st, 2021, the formal Performance Solution process came into effect under NCC Governing Requirements. The implementation of the process was in response to an expert assessment of Australia’s building regulatory and compliance systems by Peter Shergold and Bronwyn Weir. The Building Confidence Report by Shergold and Weir found systematic issues affecting application and compliance with the NCC (ABCB, 2021) and provided the following recommendations related to Performance Solutions:

• Recommendation 14 – Adequate documentation for performance solutions:

That each jurisdiction sets out the information which must be included in performance solutions, specifying in occupancy certificates the circumstances in which performance solutions have been used and for what purpose.

• Recommendation 15 – Approval of performance solutions for constructed building work:

That each jurisdiction provides a transparent and robust process for the approval of performance solutions for constructed building work?(Shergold & Weir, 2018, February).

As per the recommendations, the formal Performance Solution process provides a transparent and robust process and sets out the information which must be included in performance solutions. The process states that where a Performance Requirement is proposed to be satisfied by a Performance Solution, the practitioner developing the Performance Solution must:

???(a) Prepare a performance-based design brief in consultation with relevant stakeholders.

???(b) Carry out analysis, using one or more of the Assessment Methods, as proposed by the performance-based design brief.

????(c) Evaluate results from (b) against the acceptance criteria in the performance-based design brief.

???(d)?Prepare a final report that includes—

?????????????????(i)?all Performance Requirements and/or Deemed-to-Satisfy Provisions identified through Parts A2.2(3) or A2.4(3) of the NCC as applicable; and

???????????????(ii) identification of all Assessment Methods used; and

??????????????(iii)?details of steps (a) to (c); and

??????????????(iv) confirmation that the Performance Requirement has been met; and

????????????????(v)?details of conditions or limitations, if any exist, regarding the Performance Solution (ABCB, 2020).

In addition, all Performance Solutions need to be approved by the Relevant Building Surveyor such that the surveyor is satisfied that the Performance Solution complies the relevant Performance Requirements of the NCC. A Performance Solution must be shown to comply with the Performance Requirements through one or a combination of the following Assessment Methods:

(a) Evidence of suitability (in accordance with Part A5 of the NCC) that shows the use of a material, product, plumbing and drainage product, form of construction or design meets the relevant Performance Requirements.

(b) A Verification Method including the following:

(i) The Verification Methods provided in the NCC.

????????????????(ii) Other Verification Methods accepted by the appropriate authority that show compliance with the relevant Performance Requirements.

(c)?Expert Judgement.

(d) Comparison with the Deemed-to-Satisfy Provisions. (ABCB, 2020)

When considering the example of a rangehood in a commercial kitchen, Performance Requirement FP3.1 for Room or space heights specifies that?a habitable room or space must have sufficient height that does not unduly interfere with its intended function.?A Performance Solution can be provided in accordance with the processes and methods outlined above to support a head height clearance of 2.1m caused by the installation of the rangehood. The Performance Solution can be argued that this design will satisfy Performance Requirement FP3.1 as the rangehood will still provide a sufficient height that does not unduly interfere with the intended function of the kitchen, even if this height may be below the height stipulated in the DTS Provisions.

Furthermore, there are some Performance Requirements that do not have Deemed-to-Satisfy Solution and therefore require a Performance Solution to satisfy the Performance Requirement. An example of this is Performance Requirement GP1.1 for Swimming Pool Drainage in Volume 1 of the NCC (Performance Requirement P2.2.4 in Volume 2). The Guide to the BCA Volume 1 outlines that there are no Deemed-to-Satisfy Provisions for GP1.1 because the solution to compliance with GP1.1 will vary considerably from allotment to allotment. This does not alter the fact that compliance must be achieved with GP1.1 (ABCB, 2019).

The competent understanding and application of performance by all building practitioners can greatly improve the design processes, construction methods and the overall end product of a building. The advantages of a performance based NCC include:

• permitting the use of alternative materials, forms of construction or designs
• the innovative use of materials, forms of construction or designs;
• permitting designs to be tailored to a particular building;
• giving clear information on what the NCC is trying to achieve; and
• allowing the designer flexibility in the use of materials, forms of construction or design, provided that the intent of the NCC is met, while still allowing acceptable existing building practices through the deemed-to-satisfy provisions?(MinterEllison, n.d.).

In addition, the competent use of performance can ensure that designers, engineers and the like can have an increased focus on the users of the end product rather than a set of prescriptive requirements that must be strictly adhered to. The period of use of a building is often significantly longer than the design and construction stages, and the people using the building can sometimes become an afterthought when building practitioners try to achieve compliance during design and construction.?

DDEG can provide Performance Solutions that meet relevant Performance Requirements of the NCC for a wide range of buildings under both Volume 1 and Volume 2 of the NCC. The range of Performance Solutions that DDEG can provide include but are not limited to:

• Weatherproofing – Performance Requirements FP1.4 and P2.2.2
• Below Ground Waterproofing – Basement Perimeter Walls, Retaining Walls and the like
• Alternative Stairway Designs
• Alternative Roof Cladding Designs – Skylights, Balconies, Terraces, Concrete Roofs and the like
• Reduced Ceiling Heights
• Sanitary Facilities Occupancy Rationalisations
• Level Door Thresholds Designs
• Wet Area Designs – Level Floors, Timber Floors, Windows in Showers and the like
• Subfloor Ventilation Issues
• Reduced Natural Light and Ventilation in Habitable Rooms?–?Theatre Rooms, Basement Habitable Rooms and the like
• Swimming Pool Drainage – Performance Requirements P2.2.4 and GP1.1

In 2022, Dobbs Doherty Fire Safety Engineers, Cogent Acoustics, 3D Access, and 3D Building Solutions became DDEG: Dobbs Doherty Engineering Group, who provide Fire Engineering, Acoustic, Disability Access and Building Performance Solutions respectively.

The DTS Provisions will always be a key aspect of the National Construction Code, as they provide a general basis for which most buildings are designed to, which is still critical for the industry. However, when building practitioners have a thorough understanding and competency regarding the performance aspects of the NCC, the benefits range from the initial designers to the end users, and everything in between.

References

ABCB. (2019).?Guide to NCC Volume 1 - Building Code of Australia 2019.?Canberra: Australian Building Codes Board.

ABCB. (2020).?National Construction Code Series Volume 1 Amendment 1 - Building Code of Australia 2019.?Canberra: Australian Building Codes Board.

ABCB. (2020).?National Construction Code Series Volume 2 Amendment 1 - Building Code of Australia 2019.?Canberra: Australian Building Codes Board.

ABCB. (2021, July 15).?The NCC provision for developing Performance Solutions. Retrieved from Australian Building Codes Board: https://www.abcb.gov.au/news/2021/ncc-provision-developing-performance-solutions

Australian Building Codes Board. (2017).?Increased and competent use of performance. Retrieved from Australian Building Codes Board: https://www.abcb.gov.au/initiatives/use-performance

Greenwood, J. P. (2007). An Examination of the Performance Based Building Code on the Design of a Commercial Building.?The Australian Journal of Construction Economics and Building [Vol7, no 1], 37-44.

Heaton, A. (2018, July 20).?Myths and Facts about NCC Performance Solutions. Retrieved from Sourceable: https://sourceable.net/myths-and-facts-about-ncc-performance-solutions/

MinterEllison. (n.d.).?Chapter 8 What is the performance-based Building Code. Retrieved from Construction Law Made Easy: https://constructionlawmadeeasy.com/construction-law/chapter-8/what-does-the-bca-cover-2/

Shergold, P., & Weir, B. (2018, February).?Building Confidence - Improving the effectiveness of compliance and enforcement systems for the building and construction industry across Australia.

The Centre For International Economics. (2012, December 4).?Benefits of building regulation reform - From fragmentation to harmonisation.?Canberra: The Centre For International Economics.