When an emergency department becomes overcrowded, one response seems obvious: it needs more space.
More treatment bays. More observation beds. Perhaps additional triage stations.
Sometimes, that is exactly what the department needs. But before deciding what to build, there is another question we should ask:
Have we understood the care process that the department needs to accommodate?
It matters because a building can have more space and still struggle to move patients through the service. To understand why, we need to look beyond the rooms themselves and examine what happens inside them.
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The design starts with a patient
Every hospital design makes assumptions about the patients it will serve and the care they will need.
Those assumptions determine the journey patients must follow, the resources they require and the spaces needed to support each stage.
Consider a simplified functional model of an emergency department: triage, treatment bay, discharge.
This is not a universal description of emergency departments in the past. It is a simplified way of representing a model in which patients move from assessment to treatment and then leave the service.
But what happens when the patient’s journey becomes more complex?
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The patient changes. The process changes.
Emergency care does not always end when the initial examination and treatment are complete.
Patients may need diagnostic tests, wait for results, undergo reassessment or remain in the department while a clinical decision is made. Some need to move to observation or await hospital admission. Others may have completed the stage that requires a treatment bay but still need somewhere to remain while their care process continues.
The patient has changed, and so has the journey the department must accommodate.
A more representative functional model may therefore need to account explicitly for the stages between treatment and departure.
Not every patient follows the same route. Some leave directly after treatment; others need additional steps. The point is that the design must allow for the journeys that actually occur, rather than assuming that every patient follows the same simple sequence.
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What happens when the space does not follow the process?
This is where the problem becomes architectural.
If a patient no longer needs a treatment bay but cannot yet leave the department, the service must provide another suitable location. If no appropriate space is available, the patient may remain in the bay, occupy an observation place or end up in a corridor or another area not intended for that function.
These situations are not interchangeable, and the reasons behind them can differ. But they raise the same fundamental question: does the functional organisation of the department reflect the stages of care that patients actually need to complete?
When it does not, staff may have to compensate through operational workarounds. Spaces intended for one purpose may be used for another, and patients may struggle to move from one stage to the next.
The resulting pressure can look like a shortage of space. Sometimes it is. But the number of square metres does not, by itself, tell us whether the available space is organised around the right functions.
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Why adding more space may not be enough
When congestion appears in a particular area, expanding that area can be a reasonable response.
If treatment bays are the limiting resource, adding bays may improve performance. If observation capacity is insufficient, increasing it may help. The simulations described in the previous articles illustrate how changing these resources can produce measurable improvements.
But they also show why those improvements do not necessarily resolve every problem elsewhere in the department.
Patients must continue through the care process after leaving one space. If the next stage cannot accommodate them, congestion may persist or appear in another area.
The problem is not that expansion is inherently wrong. It is that we can increase the capacity of one part of a department without resolving the constraint that limits the system as a whole.
More space is useful when it addresses a genuine capacity need. The challenge is identifying that need before deciding what to build.
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Three questions should come before the design
My research points towards a different starting point for planning emergency departments. Rather than beginning with a target number of treatment bays or a proposed increase in floor area, the process should begin with three questions.
First, who is the patient we need to serve?
What characteristics and care needs define the population using the department? How do those needs differ across patients, and what implications do they have for the resources required?
Second, what care process does that patient actually follow?
Which stages must the patient complete? What happens between assessment, treatment and departure? Where are tests, reassessments, decisions and transitions accommodated? How long do patients occupy each resource, and what happens when the next stage is unavailable?
Third, what spaces does that process require?
Only after understanding the patient and the process can we make more informed decisions about the number, type and relationship of treatment bays, observation places, transit spaces and other facilities.
The sequence matters: patient, process, design.
Starting with the building and working backwards risks reproducing an existing layout without first checking whether it supports the care process the department now needs to deliver.
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Designing for how emergency care actually works
This approach connects three dimensions that should not be planned independently: the needs of the patient, the operational process and the architecture that supports it.
The DFU simulation model developed as part of my research provides a way to explore how changes in demand, resource occupancy and available capacity affect the operation of the system. It does not replace clinical judgement or prove that a single design will work in every hospital. Its value is that it allows different configurations and scenarios to be examined systematically.
That is the broader point. Hospital design should not begin and end with the question of how much space is available. It should establish what the space needs to make possible.
An emergency department may need more treatment bays, more observation capacity or additional transit space. In some cases, it may need several of these. But those decisions should follow an understanding of the patient journey and the points where that journey becomes difficult to sustain.
Before deciding how much space an emergency department needs, we must understand the patient it serves and the care process that patient actually follows.
About this research
This article draws on a four-month research project conducted as part of my Master’s Final Project in Hospital Engineering and Architecture at the University of Cádiz, Spain, which received a grade of 9.5/10.
The research examines demographic trends, hospital designs and functional plans, emergency care processes, and the perspectives of emergency department professionals gathered through surveys. It culminates in the development of a digital twin simulation model designed to explore multiple scenarios and analyse how different factors affect emergency department operational capacity.