Designing IL4 Facilities for Real-World Resilience: Why Step One Matters
- Vanessa Galina
- 1 hour ago
- 5 min read
Importance Level 4 facilities play a critical role in community resilience. These are the buildings and infrastructure assets expected to remain available when communities need them most — during and after major disruption.
For healthcare, emergency response, critical utilities and other essential services, the expectation is not simply that a building survives an event. The real question is whether the facility can continue to support its intended post-disaster function.
That distinction sits at the heart of Jordan Bartlett’s AEES 2024 paper, IL4 Special Study Step One: Critical Success Factors. The paper explores how organisations can better define what they need from an IL4 facility before design decisions are locked in.
Moving beyond minimum compliance
The National Construction Code and AS 1170.4 provide important requirements for earthquake design and post-disaster functionality. However, Bartlett highlights that IL4 Special Studies are not always applied consistently, and in some cases may be limited to the concept or design phase without being properly carried through delivery, commissioning and verification.
This creates a practical challenge for owners, operators, design consultants and project teams. A facility may be designed to meet a technical requirement, but still fall short of the operational outcomes expected by the people who need to use it after a disruption.
The paper argues that the first step of the IL4 Special Study process — establishing post-disaster operational requirements — deserves much deeper attention.
The three key questions
Bartlett breaks Step One into three practical sub-stages:
What hazard events need to be considered?
What minimum business continuity objectives must the facility support?
How long does the facility need to keep operating after a disruption?
These questions sound simple, but they are often not answered clearly enough at the beginning of a project. When they are left too late, the design team may not have the opportunity, budget or scope to meaningfully embed resilience into the building.
Designing for all hazards, not just earthquakes
Although IL4 Special Studies are closely associated with seismic resilience, Bartlett makes the case for a broader all-hazards approach.
Earthquakes are only one possible disruption. Critical facilities may also face wind, flood, bushfire, utility failure, hazardous material incidents, cyber disruption, security risks or other human-caused events.
For Australian projects, this is particularly important. Bushfire, flood, cyclone, heat, utility disruption and regional isolation may all influence whether a facility can remain operational when it is most needed.
Expanding the IL4 Special Study to consider other relevant hazards can help project teams identify vulnerabilities earlier, avoid duplication of controls and develop more integrated design responses.
Business continuity must inform building design
A key theme of the paper is the gap between organisational business continuity planning and facility design.
Many organisations have Business Continuity Plans, but these plans often focus on people, equipment and processes rather than the building itself. They may assume that a backup facility will be available, that external services will recover quickly, or that the organisation will be prioritised for scarce resources after a major event.
Bartlett challenges these assumptions. In a widespread disruption, nearby backup facilities may also be affected. Utilities may be unavailable for extended periods. Fuel, water, sewer, communications and staff access may all become limiting factors.
For this reason, business continuity objectives need to be translated into facility design requirements early in the project.
What must keep working?
One of the most useful concepts in the paper is the categorisation of Minimum Business Continuity Objectives.
Bartlett groups facility functions into three broad categories:
Primary functions are the critical functions that must continue immediately during and after a disruption.
Secondary functions are essential services that should be restored soon after the event to support broader response and recovery.
Tertiary functions are discretionary services that may only be restored once resources are stable or external assistance is available.
This approach gives stakeholders and design teams a clearer language for prioritising what matters most. Not every function needs the same level of protection, redundancy or immediate restoration. The goal is to make those decisions deliberately rather than by assumption.
Island mode and assisted island mode
The paper also explores the concept of “island mode”: the period during which a facility may need to operate without external support.
This is especially relevant for healthcare and other critical infrastructure facilities that may need to continue operating during extended outages of electricity, potable water, sewer, communications or fuel supply.
Bartlett also introduces the idea of “assisted island mode”, where the facility begins to receive limited external replenishment while still operating under constrained conditions. For example, fuel deliveries may allow critical and essential functions to continue for longer, while some discretionary functions are gradually restored.
This distinction is valuable because it reflects the reality of disaster recovery. Recovery is rarely instant. Facilities may need to operate in a staged, resource-conscious way for hours, days or longer.
Redundancy needs to be tested, not assumed
Redundancy is often treated as a building services issue, but Bartlett warns that duplication alone does not guarantee resilience.
If backup systems depend on the same vulnerable pathway, location, fuel source, communications link or maintenance access, they may still share a single point of failure. Effective redundancy requires independence, separation and a clear understanding of what systems must support which functions, and for how long.
This is where early stakeholder engagement becomes essential. Facility managers, operational leaders, emergency planners, clinicians, engineers and asset owners all hold pieces of the resilience puzzle.
A practical framework for better conversations
The strength of the paper lies in its practical focus. It encourages project teams to ask better questions at the concept stage, including:
What is the facility’s role after a disaster?
What contents, systems or services must be protected?
Which functions are critical, essential or discretionary?
What outage periods are acceptable?
How long must the facility operate without outside support?
Which external services are likely to fail?
What assumptions are being made about priority access to fuel, water, power, staff or communications?
How will resilience requirements be verified at handover?
These questions help move IL4 resilience from a compliance exercise to an operational design process.
Why this matters for healthcare infrastructure
For healthcare engineering and health infrastructure professionals, the implications are significant.
Hospitals and health facilities are not just buildings. They are complex operational environments that rely on power, water, medical gases, communications, supply chains, staff access, infection control, clinical workflows and public trust.
A facility that remains standing but cannot support critical clinical operations may not meet the real intent of post-disaster resilience.
By embedding operational requirements early, project teams can better align structural design, building services, emergency management, asset planning and business continuity.
The key takeaway
IL4 resilience starts long before construction.
It begins with a clear understanding of what the facility must do after a disaster, which hazards could disrupt that role, which functions must be protected, and how long the facility must operate under constrained conditions.
Bartlett’s paper reinforces an important message for the sector: critical infrastructure resilience cannot be left to assumptions, minimum compliance or late-stage business continuity planning.
To deliver facilities that are genuinely disaster-ready, owners and project teams must define success early — and carry those requirements through design, procurement, construction, commissioning and verification.
To hear Jordan speak further on this important topic, join us for our next Lunch + Learn - Built to Withstand: Designing Healthcare Facilities for Multi-Hazard Resilience.
Wed, 15 July | https://us02web.zoom.us/j/85764444638
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