Introduction to Human-Centered Design in the NCC
There are several forms of published media on design and design principles but there are none quite like ‘The Design of Everyday Things,’ by Don Norman. Don Norman is a cognitive scientist and usability engineer sometimes referred to as, the ‘Father of User Experience.’ He has worked as an industry executive for Apple, HP and a few startups.
In his book, Norman details how design is the bridge between the product, the user, and how to improve the user experience. He describes the psychology behind good and bad design, so much so that a poorly designed door that has been identified as confusing to utilize has been named after him. A Norman door.
Design is not just something essential to designers and engineers to perform their job but also something the average person does, unconsciously and instinctively. We design our rooms, our lives, and our processes. For example, a simple morning routine has the necessary steps such as going to the toilet, brushing your teeth, washing your face, making and eating breakfast, packing lunch and then getting dressed. Every person will complete these tasks in their own formulated way.
Their very own design.
Good design is hard to perfect and barely noticeable, whilst poor design has inadequacies and causes problems and frustrations for the user. A successful product needs to consider the ‘user experience’ or ‘UX’. Like anything else that is designed, the National Construction Code (NCC) has considered the human aspect of human-centred design (HCD). In particular, the last iteration of the NCC (NCC 2022) not only moved towards a web-based version but also had a major structure and format change, intended to improve useability suited to a more modern approach.
Principles of Human-Centered Design in Section D
In terms of content of the NCC, Section D heavily considers human behaviours for access and egress being that it is a common and critical action for people in buildings. The section focuses on specifying the number, location, dimension and placement of exits. It also considers travel distance to exits, construction of exits including stairways, ramps, handrails, balustrades and the operation of doors to enable safe evacuation and provide access to and within buildings for people with disabilities. It also includes measures intended to reduce slips, trips and falls. All of which has been designed with human interaction in mind.
Two of the four principles of Human-Centred Design (HCD) play an underlying role in Section D. These are focussed on the people using the design and considering where the design fits into the big picture. One such instance of the above occurs in BCA Clause D2D5, for exit travel distances. The clause specifies the maximum distances to exits for different building classifications, such as, 6 m to an exit for Class 2 and Class 3 residential buildings as shown in Figure 1 and 20 m for other building classifications.
The shorter maximum travel distances for the residential building classifications, considers the distance occupants need to travel within their unit, as well as the time occupants are required to wake up, become alert and exit in a state of confusion.
The BCA clause indirectly considered the condition of sleeping occupants, recently awoken and common building design to stipulate the shorter travel distance.
Figure 1. Extracted from the NCC 2022 Guide to D2D5 Exit travel distances
Doorway Design Requirements: BCA Clause D3D24
Chapter 1 of the book, ‘The Psychopathology of Everyday Things’, delves into the two important aspects of good design: Discoverability and Understandability. Discoverability is further broken down into, affordances, signifiers, constraints, mappings and feedback.
A well-designed door will consider these aspects to achieve its intended purpose, providing access or egress. This is detailed out in BCA Clauses D3D24 – Doorways and Doors.
D3D24 specifies the requirements for doorways, serving as a required exit or forming part of a required exit. Such exits may not be fitted with a revolving door, roller shutter, sliding door or power-operated door with certain concessions permissible. The intent of the clause is to minimise the risk that a door may obstruct when a person tries to evacuate. The aforementioned doors provide a level of complexity for door operation and disrupts the user in determining the possible actions (affordances). To reduce the complexity, signifiers are provided to help users identify available actions, such as an emergency push to open button, placed adjacent to a power-operated door. This is put in place so that anyone approaching the door will be able to observe and press the exit button.
Re-entry from Fire-Isolated Exits: BCA Clause D3D27
Understanding and knowing what to do is a key aspect to design and usability. The user needs to determine the constraints of the product/design, discoverability of the actions and feedback to the actions. Additionally, design should consider errors that users may make. This includes understanding and minimising the cause of error, performing sensibility checks, making actions reversible or irreversible actions more difficult and allowing errors to be easier to discover, and easier to correct.
This is applied in BCA Clause D3D27 – Re-entry from fire-isolated exits.
Fire-isolated exits generally provide one way access as they are designed for people using a fire-isolated exit to enter a ‘safe place.’ Once inside, this will eventually lead them towards a road or open space.
BCA Clause D3D27 allows Class 9a health-care buildings, Class 9b early childhood centre buildings, Class 9c buildings and fire-isolated exits serving any storeys above 25m not be locked from the inside, as shown in Figure 1. This is so that occupants may leave a compromised exit for an alternative exit on the same storey. Due to security concerns, the BCA clause also provides alternative scenarios for Class 9a and 9c buildings and fire-isolated exits above 25 m where doors are fitted with a fail-safe device that automatically unlocks the door when a fire is detected. This permits every fourth storey to remain unlocked in lieu of every storey. A sign is fixed on those doors, stating re-entry is available or an intercommunication system is provided near the door in the exit with a sign explaining purpose and method of operation.
Figure 2. Extracted from the NCC 2022 Guide to D3D27 Re-entry from fire-isolated exits
In the scenario where someone mistakenly enters a fire-isolated exit, the above measures provide the option to leave the fire-isolated exit without having to travel all the way down towards the exit. Occupants in the fire-isolated exit will then either be able to discover a level that provides re-entry into the building or an intercommunication device to communicate their predicament. Clause D3D27 understands that errors can be made and allows occupants to make a reversible action to leave the exit or correct their error by either communication with others outside or finding another level that provides re-entry.
Conclusion
The application of the design principles outlined in, ‘The Design of Everyday Things’ by Don Norman in the NCC provides reassurance that buildings designed in Australia have considered the occupants using them in terms of safety and usability. The average person is unlikely to notice the above design principles in their day-to-day life, as good design is hard to perfect and less detectable. However, they can trust the intent of the NCC to set the minimum required level for the safety, health, amenity, accessibility and sustainability of certain buildings.
References
Norman, D. A. (2013). The design of everyday things (Revised and expanded edition). Basic Books.