The short answer
High Performance HMI Design
High performance HMI is a design approach where operator displays are built to make abnormal conditions immediately obvious. Backgrounds are low-contrast grey, process elements are drawn in muted outline, and saturated color is reserved almost entirely for alarms and abnormal states. It is codified in ISA-101 and stands in contrast to the photorealistic, heavily colored graphics that dominated early SCADA.
Key points
- Color carries meaning. If everything is colored, color means nothing.
- Grey backgrounds with muted process elements make an abnormal condition jump out.
- Analog values benefit from context: a bar with limits beats a bare number.
- Hierarchical displays let an operator move from plant overview to detail predictably.
- The test is whether a new operator can identify the abnormal item in a few seconds.
The problem it solves
Early SCADA graphics were built to impress. Three-dimensional tanks, green running pumps, blue pipes with animated flow, red where something was off. In a demonstration this looks like a control system. At 3 a.m. during an upset, an operator has to find the one abnormal item on a screen where everything is already vividly colored, and the search takes far longer than anyone estimates.
High performance HMI inverts the design. The normal state is deliberately quiet. Anything that draws the eye is doing so because it needs attention.
Core principles
- Low-contrast grey background
- A mid-grey field rather than black or white. It reduces eye strain over a twelve-hour shift and gives both light and dark elements room to stand out.
- Reserved color
- Saturated color is used almost exclusively for abnormal conditions and alarm priority. Running equipment is a subtle outline change, not a green fill.
- Depiction over decoration
- Flat, two-dimensional shapes. No bevels, gradients, or photorealistic vessels. They add nothing an operator uses and cost visual bandwidth.
- Analog context
- A number alone tells you the value. A number with a bar showing the normal operating range and the alarm limits tells you whether to care.
- Consistent layout
- The same information in the same place on every display. An operator should not have to search for where a pump status lives on this particular screen.
- Deliberate hierarchy
- Level 1 plant overview, level 2 process area, level 3 equipment detail, level 4 diagnostics. Navigation between them is predictable and always available.
A workable color convention
| Meaning | Treatment | Notes |
|---|---|---|
| Normal running | Dark outline, light fill, no saturated color | Status is legible without being loud |
| Normal stopped | Same shape, lighter fill or hatched | Distinguishable at a glance without color |
| Critical alarm | Saturated red, usually with a shape indicator | Reserved exclusively for this |
| High priority alarm | Saturated amber or orange | Reserved exclusively for this |
| Low priority alarm | Yellow, lower emphasis | Reserved exclusively for this |
| Bad or stale data | Hatching, greying, or an explicit marker | Must never look like a live value |
| Operator command in progress | Brief distinct treatment | Confirms the system heard the command |
Displays for a water utility
A municipal utility has a specific shape of problem: many similar remote sites, a plant, and a small number of operators covering all of it.
- Build one standard lift station display and reuse it for every station. Operators learn one layout instead of sixty.
- The overview should answer the only question that matters on a callout: which sites are in trouble right now.
- Show communication health explicitly. A station that has not reported is a different problem from a station reporting a high level.
- Put pump run hours and start counts where they are visible. This is how maintenance planning actually happens.
- Trend wet well level directly on the station display. The shape of the last few hours tells an experienced operator more than any single number.
Retrofitting an existing system
Rebuilding every graphic at once is rarely fundable, and it disorients operators. A staged approach works better.
- 01Write a short style guide first, even one page. Without it, the second display will not match the first.
- 02Fix color misuse before layout. Removing saturated color from normal states is the highest-value change and the cheapest.
- 03Add analog context to the values operators actually watch, starting with levels and pressures.
- 04Build a genuine overview display if none exists. Most systems do not have one.
- 05Convert area displays one at a time, with operator review at each step.
- 06Involve the people who run the plant at night, not only the day shift. They see different problems.
Frequently asked questions
- Is ISA-101 required?
- No. It is a consensus standard describing a lifecycle for HMI design. It is often cited in specifications and is treated as good practice, but it is not a regulation for municipal water and wastewater.
- Will operators accept grey screens?
- Usually yes, once they have worked a shift on them, and the objection almost always comes before the trial rather than after. Involving operators in the design and converting one area first makes the difference between adoption and resistance.
- Should running pumps be green?
- Under this approach, no. Green fill on every running pump spends your most attention-grabbing resource on the most common and least interesting state. Use a subtle outline or fill difference for running, and keep saturated color for conditions that need action.
- How many displays should a system have?
- As few as will cover the plant with a clear hierarchy. Large numbers of near-duplicate displays are a symptom of missing reusable templates, and they multiply the cost of every future change.
Related topics
- ISA-101: Human Machine InterfacesWhat the ISA-101 standard for human machine interfaces covers, its lifecycle from philosophy to maintenance, the display hierarchy, and what adopting it changes on a project.
- Situational AwarenessDesigning displays so an operator knows what is happening, what it means, and what comes next: the three levels of awareness, the display hierarchy, analog indicators with normal ranges, embedded trends, time-to-limit predictions, and a test for any display.
- ISA-18.2 Alarm ManagementThe lifecycle standard for alarm systems, the rate targets that define a workable system, and why alarm rationalization is the step nobody wants to fund.
- HMI FaceplatesThe pop-up that controls one device: what a pump, valve, or loop faceplate must show, the mode and command layout, interlock and permissive display, security by role, and building faceplates from a standard object so every device behaves the same.
- HMI NavigationHow operators move through the displays: the display hierarchy from overview to detail, a fixed navigation bar with area alarm indication, one-click paths from an alarm to the device, the rules that keep any display within two clicks, and what to leave out.
- Color in HMI DesignHow color is used on a high performance HMI: a gray palette for normal operation so that color means something, alarm colors reserved by priority, equipment state by fill and text rather than red and green, color-blind safe choices, and the palette table.
Direct contact
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