Short answer
It helps as a secondary cue: a colour tied to a zone, floor or route lets people confirm they are in the right place and remember where they parked. It fails when it is the only cue, when there are too many colours to remember, or when colours collide with safety meanings — green is already the colour of escape routes. Effective schemes pair each colour with a name, number or symbol and keep it consistent everywhere it appears.
Colour is quick to notice and needs no reading, so it is good at answering 'am I still in the right area?' A hospital that makes every sign, door frame and floor strip in its outpatient zone the same colour lets a visitor confirm at a glance that they have not wandered into another department. Car parks colour levels so that people remember 'the blue floor' when they have forgotten 'level 3'. Transit networks colour lines so that a route can be followed through a map and a station. In each case colour is reinforcing a structure that also exists in words and numbers; it makes the structure easier to hold in memory, rather than replacing it.
People with colour-vision deficiencies — around one man in twelve of northern European ancestry — may not separate some pairs of colours at all, and many older people see colours less vividly. Lighting changes appearance: a pale blue and a pale green can look the same under warm lamps. Memory is limited too; a scheme with a dozen hues asks people to learn a code, and near-neighbours such as two blues are easily swapped. The web's accessibility rules say colour must not be the only means of conveying information, and the same principle applies in buildings: every colour-coded zone should also have a name, number, letter or symbol, and signs should work in greyscale.
Safety colours have legal meanings at work in Europe and the UK: red for prohibition and fire-fighting equipment, yellow for warning, blue for mandatory action, green for escape routes and first aid. A wayfinding scheme that uses a strong green for a department risks being read as an escape route, and red zones can look like fire-equipment points. That does not rule these hues out, but it argues for using them on shapes and in places that cannot be confused with safety signs, and for keeping the safety colours on safety-shaped fields for safety messages. It also argues for consistency: if red means a department in one wing, it should not mean 'no entry' in another.
A useful audit is to photograph a colour-coded route and view it through a colour-vision-deficiency simulation. If the route disappears, the non-colour cues are not doing enough work.
The colour of a wayfinding element matters less than whether it stands out from its background. A floor strip that is a different hue but the same lightness as the floor is invisible to many people with low vision; a door frame that contrasts in light reflectance value with the wall helps everyone find the door. UK guidance frames visual contrast as a difference in light reflectance value, and a wayfinding scheme that ignores it can look coordinated on a drawing and fail in the corridor. Choosing a scheme's colours therefore starts with lightness contrast against the building's finishes and only then with hue.
Why: Two zones use similar blues, and signs rely on colour without distinct names or numbers.
Fix: Reduce the number of hues, separate them in lightness, and give every zone a name or letter shown with its colour.
Why: Green on a rectangle is the safety colour for escape routes.
Fix: Use a different hue or a clearly different sign format for departmental wayfinding.
Why: The line differs in hue but not in lightness from the floor.
Fix: Check the LRV difference and choose a line colour that contrasts in lightness.
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
StandardStrong evidence
WCAG requires that colour not be the only visual means of conveying information, indicating an action or distinguishing an element.
Caveat: WCAG applies to web content; its application to buildings here is by analogy.
Source: Web Content Accessibility Guidelines (WCAG) 2.2; International Organization for Standardization (ISO) catalogue
StandardStrong evidence
Under the GB safety-signs regulations, green signifies emergency escape routes and first aid, and red identifies fire-fighting equipment.
Source: The Health and Safety (Safety Signs and Signals) Regulations 1996 (SI 1996/341)
ConventionModerate evidence
Colour coding by line or zone is an established wayfinding convention in transit networks, where each line has kept a distinct colour on maps and signage for decades.
Source: Tube map (Wikipedia); Design standards
Colourwise interpretationModerate evidence
Colour-coded wayfinding works best as a redundant cue alongside names, numbers or symbols, and with each colour chosen for lightness contrast against its background.
Based on: Combines the colour-not-alone principle in accessibility standards, the LRV-difference definition of visual contrast in UK building guidance, and the prevalence of colour-vision deficiency.
Reviewed 29 September 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.