Interior Design

The art or practice of enhancing the function and quality of interior spaces by planning the design and supervising the implementation of architectural interiors and their furnishings.

Achromatic Colours

Black, white and grey.


Afterimage is a phenomenon associated with complementary colours, created by prolonged exposure to an intense hue.  Exposure to an strong colour for an extended period of time causes the observer to ‘see’ an afterimage of the opposite hue after looking away.   Staring at an intense red hue for a prolonged period of time, will produce a green afterimage once the observer looks away.   The designer should be aware that, if strong hues are used where the eye may focus for any length of time, afterimage can affect the perception of surrounding colours in an interior scheme.


Although beauty is subject to highly individual interpretation, and conditioned by time and culture, the qualities of a design that please the senses and lift the spirit are generally achieved through the application of the Principles of Design (Nissen et al, p.15).

Bright Colours

Bright colours result from mixing chromatic colour with little or no achromatic colour (black, white or grey).

Bubble Diagram

Bubble diagrams represent the first stage in planning.  A diagram in which bubbles represent activity zones placed in proximity relationships.  Bubble diagrams may be refined to depict space adjacencies and circulation patterns between zones, as well as the shape and size of the rooms.

Bubble diagrams only


Character differentiates one home from another; it is the result of the expression of style and the individual personality of each household member (Nissen et al, p.12).  Even when a particular style of design is adopted, such as Georgian or Minimalism, the home should still reflect the unique personality of its residents, rather than merely faithfully recreating the various components of the style.

Chromatic Colours

Any colours other than white, grey and black.


After the programming phase, programme data is analysed and circulation routes (traffic flow) between rooms or areas is carefully evaluated as an important first step in space planning.  Space is allocated to rooms or activity areas, as well as to the circulation system (comprised of entry halls, corridors, concourses and stairways) that will accommodate movement between them.

Major circulation routes through a building are determined by architectural structure (such as walls, doors and their direction of swing); minor traffic paths within individual rooms or areas are influenced by furniture placement and the space needed to perform activities in each area.

A good circulation plan avoids inconvenient routes and invasion of privacy and deters traffic crossing activity areas to minimize the risk of accident.  In the interests of space economy and efficient traffic flow, circulation routes should be short, direct and as free of turns as possible (Nissen et al, p.188).  The most frequently travelled routes (major and minor) should be the shortest (Nissen et al, p.189).  Fewer structural walls allow for easier traffic flow (Nielson & Taylor, p.130).

Traffic patterns must be allocated adequate width.  Minimum passage width is 91 cm (3ft) but the study of proxemics (interpersonal space) suggests that passing in such a narrow space might cause a degree of psychological discomfort to people who are not well acquainted, with the result that one would probably stand back for the other to pass.  Hallways in average homes are usually over 1 metre wide, but 107-122cm is more appropriate for major circulation routes accommodating heavier two-way traffic, and for moving furniture.  The greater the volume of traffic, the wider the traffic flow routes will need to be.  Building codes stipulate minimum corridor widths for non-residential buildings.

Ideally, rooms should be accessible without having to go through one to reach another, but where rooms must be used for circulation, the space should be planned so that the most direct route is along one side or across a corner, rather than crossing through the centre of activities or seat groupings.  The space allocated to the circulation route should also be wide enough that the traffic flow does not interfere with the activity in the room.  Furniture placement should allow traffic to flow, or redirect the traffic to eliminate unnecessary or disruptive flows.

To analyse traffic patterns, lines and arrows may be drawn on a bubble diagram or floor plan to show where people will be walking. These circulation routes should be kept as empty and as direct as possible.  On a floor plan, natural traffic patterns can be identified – routes where we would logically walk to get from one space to another – and the flow may need to be controlled and diverted (by devising a corrected plan) away from areas where it would cut through seating arrangements or disrupt activities.  In public buildings and spaces, circulation is improved where the design makes it is clear to people how to enter, how to find their way around, and how to get out (Nielson & Taylor, p.130).


A characteristic of light or of object surfaces that is perceptible to human vision and that is described by various colour names, such as red or blue (Pile, p.13)

Commercial Design

The design of non-residential interiors (cfResidential Design).  Also known as Contract Design.

Complementary Colours

Colour combinations that appear opposite one another on the colour wheel, such as red and green, orange and blue, yellow and violet.

Concept Statement

Initial written statement of the principal workable idea(s) in response to the design problem, expressing the main ideas and approach behind the proposed design solution.

Construction Drawings

Also known as ‘Working Drawings’.  Final working drawings: plans; elevations, sections and details accompanied by drawing notes.

Contract Design

The design of non-residential interiors (cf. Residential Design).  Also known as Commercial Design.


Contrast, or opposition, is the arrangement of opposites of an element to create visual interest and drama.  Contrast is the difference between colours, values, patterns, shapes, forms or textures, or in light or line.  Large variances or abrupt changes are described as ‘sharp’, ‘high’ or ‘vivid’ contrast; small variations are described as ‘low’ contrast.

Contrast in colour may involve using complementary colours which sit opposite one another on the Brewster-Prang colour wheel; or placing high key colours (light values) next to low key colours (darker values) next to one another, with no progression through middle values between them.  Contrast can be seen in patterns, between busy and plain; light and dark; small repeat and large repeat.  Contrast in shape, form and line involves the juxtaposition of angular shapes and rounded shapes; of large and small; of solid, visually ‘heavy’ objects and light, delicate ones; or of straight lines with curves and verticals with horizontals.  Contrast in either tactile or visual texture can play on the dissimilarity between surfaces which are hard and soft; matt and polished; patterned and plain; warm and cool; rough, bumpy or jagged and smooth and even.

Contrast makes individual objects more interesting and meaningful, provides relief from uniformity and adds asymmetrical balance to a scheme.  Restraint in the variety of some elements (such as colour) should be counterpoised by range and contrast in others (such as texture or colour value) in order to provide interest.

Cool Colours

Colours near the violet end of the spectrum are designated as cool.  Green and blue are cool colours.  Violets may be either warm or cool, depending on their relative content of red or blue.  Greys and other neutrals may be warm or cool, according to their content of warm or cool chromatic colour.

Critical Path

A schedule of activities required to complete the design project, showing the time that each activity will take to complete and the dependencies between activities and highlighting milestones towards the final output.


See Lightness


The process of placing a two- or three-dimensional representation of the proposed space on paper.

Dull Colours

Dull colours result from mixing chromatic colour with a complementary colour, with an achromatic colour, or with both.


One of the objectives of design.  Economic factors are critical in determining the feasibility, scope and quality of the design project.  Economic considerations will affect all aspects of the design process, from the time allotted to research, develop and execute the design to the quality of materials and furnishings (Nissen et al, p.15).  Economy refers not only to monetary resources, but also to human, material and environmental resources (which also have a bearing on costs).

Elements of Design

There are 8 or more elements of design (acronym SMaLL PaCTS):

  1. Space (the physical boundaries of a room)
  2. Mass (the actual or apparent density of an object)
  3. Light (natural and artificial)
  4. Line (created by the furnishings and architecture of a room)
  5. Pattern (repetitive design)
  6. Colour
  7. Texture (the feel, appearance or consistency of a surface)
  8. Shape (2-D outline) and Form (3-D configuration)


Also referred to as ‘utility’.  Design must satisfy the functional or utilitarian needs of the residents or users for whom the space is designed.  The credo form follows function, coined by the American architect Louis Sullivan towards the turn of the twentieth century, denotes that the form of an object or space should be a straightforward rendition of its proposed use.

Among the factors that inevitably influence the design of a space, a paramount consideration is the function(s) that it will serve, and the designer’s priority is to devise solutions that fulfil these functional requirements.  Functional performance is regarded as the first test of design quality for interiors (Nissen et al, p.54).

Function is not an absolute determinant of form.  That is to say, a given end use might be accommodated equally well by a number of different designs: the requirement that a seat be comfortable is met by millions of strikingly different designs of chairs.

The functional segment of the client brief describes, among other things, how the space is used, by how many people, how often and at what times of day, and whether the end-users have special requirements in terms of access or mobility.  This information will inform such determinations as how much space should be allocated to each room, zone or activity; adjacency relationships to other related spaces (since functions should flow smoothly from one zone to another); the design and placement of architectural elements; seating, work surface and storage space requirements and configurations; lighting, wiring, heating, and plumbing layouts; and which materials, finishes and colours would be best suited to the proposed end-uses of the space.


See Progression.


Harmony consists in achieving a balance between unity and variety.  Unity involves combining elements and furnishings with a fundamentally similar or compatible character (for example, by using a cohesive colour scheme or furniture of a consistent style), and in such a way that subordinate elements complement dominant ones, in order to achieve a consonant and unified overall scheme.

Variety is the absence of sameness; it adds interest and excitement.  Unity and variety complement and balance one another. Unity without variety would result in sterility and monotony; while a cacophony of assorted and competing shapes, colours, patterns and styles, without some unifying elements would seem chaotic, dissonant and lacking in visual clarity.

It is possible to achieve a pleasing balance somewhere between the extremes of monotony and excessive variety, by holding most of the design elements – shape, form, mass, line, light, pattern, colour and texture fairly constant, or at least keeping them compatible or proportional, and varying or contrasting only one or two elements.  Objects have numerous properties, and it is possible to unify by coordinating certain aspects such as colour, material, shape, texture or period, while retaining variety in others.


Hue is the quality that gives an identifying name to a chromatic colour.  The terms hue and colour are often used interchangeably.

Lightness and Darkness

The degree to which a colour reflects light.  Light colours reflect much of the light that falls on them and are called pale or pastel.  Dark colours absorb much of the light that falls on them and reflect little light.


A maquette is a detailed plan, often used in 18th century decorating practice, showing all furniture and other elements in top view, and surrounded by four elevations representing each wall of the room.  Furniture is depicted on the elevation of the wall to which it will be closest.  The elevations are placed directly adjacent to their their respective side of the floor plan, so that they can be thought of as walls, cut out and folded up into a vertical position to create a box arrangement – a simplified 3-dimensional model of the room.  This form of presentation works better for conventionally shaped spaces than for irregularly shaped ones.


Mood is one of the basic considerations in the design of an interior.  The mood or atmosphere of an interior space relates to how it makes users feel.  It can be relaxed or formal; opulent or austere; stimulating or relaxing; cool and airy or warm and intimate.  It is important to consider mood when planning an interior design scheme.  Mood should be appropriate to the function of a room – for example, stimulating red hues might be less suited to a bedroom than would relaxing pastel or neutral hues.  Different colours, textures and lighting effects can convey different moods within an interior space: darker colours and subdued lighting can create an intimate mood; vibrant colours and bright lighting can produce a more stimulating atmosphere.

Neutral Colours

Neutral tones are produced by mixing complementary colours.  Mixing a chromatic colour (one which is not white, black or grey) with an achromatic colour (white, black or grey) will partially neutralize the resultant colour.

Objectives of (Good) Design

The objectives of good design (remembered by the acronym CUBE) are:

  1. Character – the result of the expression of style and individuality
  2. Utility – the functional purpose of the space
  3. Beauty – achieved through the application of design principles
  4. Economy – economy of monetary, human, and natural resources


See Contrast.

Post-occupancy Evaluation (POE)

An important final stage in the design process.  Post-occupancy evaluation involves following up on the completed job to measure the success of the design solution.  POE may involve a questionnaire, interview or walk-through inspection with the client so that the designer can make any adjustments to improve the result.  Evaluation may also be invited from peers.  The process may be repeated at appropriate intervals.

Primary Colours

Colours that cannot be produced by mixing other colours, but which can be blended to produce almost all other colours.  The primary colours are red, yellow and blue.

Principles of Design

Certain aesthetic concepts have evolved to explain how and why certain combinations and relationships of elements are pleasing.   These are the principles that should govern the use of the Elements of Design (remember the acronym HERBS):

  1. Harmony (through Unity and Variety)
  2. Emphasis
  3. Rhythm
  4. Balance
  5. Scale and Proportion

These principles represent yardsticks against which to evaluate the success of design in achieving the Objectives of good design: Character, Utility, Beauty and Economy (CUBE).

Programme Document

The design programme document, the initial stage in the Design Process, identifies all the factors that must be considered for a successful design solution.  It identifies the goals, defines the requirements and clarifies any restrictions on the design project.


Progression, or gradation, is a type of rhythm which consists of repetition of one or more qualities of a design element (such as shape, mass, light, line, pattern, colour, texture or space) in an escalating or diminishing sequence.  Progression involves using, for example a progressive ‘value distribution’ (a sequence of colour values which are gradually lighter or darker); or using a variety of objects or pattern repeats which are progressively smaller or larger (such as nesting tables, or a ‘wedding cake’ arrangement of steps around a fountain); or applying a range of textures in successive degrees from rough to smooth, or hard to soft.  Although progression is more dynamic than simple reiteration, variations in the characteristics of an element are gradual and subtle and the result is a more calming and orderly scheme than contrast, which involves abrupt shifts between poles such as light and dark, or patterned and plain, to produce a more dynamic and dramatic effect.


After the initial concept development stage of the design process, and based on the Concept Statement, a proposal is presented to the client for review, feedback and approval.  The proposal will include the Design Concept, comprising conceptual drawings and scaled floor plans showing furniture placement, and one or more moodboards proposing colour, materials and finishes.  Depending on the scale of the project, the proposal may include additional sketches, perspective drawings, full colour renderings, 3-D models and computer simulations.  The proposal will also include a budget estimate as well as a time frame showing events in sequence and a completion date.

Punch List

Also known as a ‘Snag List’, is a list of usually minor remedial works that need to be completed so that the standard of work meets the specification.

Residential Design

The construction or remodelling of private residential space on behalf of the end-user client (cf. Contract Design, also known as Commercial Design).


Details the type and placement of each colour, material or style (paint, trim, wall coverings, etc.) in an interior.


Schematics are quick drawings or sketches to visualise ideas, space allocations, circulation patterns (‘traffic flows’), spatial and activity relationships, colour schemes and other important details of a design.

Secondary Colours

Secondary colours are those formed by mixing two primary colours.  The secondary colours are orange (a mixture of red and yellow); green (a mixture of blue and yellow); and violet (a mixture of blue and red).


A shade is a darker colour tone produced by mixing  a chromatic colour with black or dark grey.

Snag List

Also known as a ‘Punch List’, is a list of usually minor remedial works that need to be completed so that the standard of work meets the specification.

Space Allocation

To assign an area (or volume) of space to a given function, in determining the location and layout of rooms or zones.


A written list with detailed descriptions of all materials, furnishings and accessories to be acquired.


The decorative design of an interior.

Tertiary Colours

Tones formed by mixing a primary colour with its adjacent secondary colour, such as red-orange, blue-green.  There are six tertiary colours, resulting from the six possible permutations of primary and adjacent secondary colours.


Texture is the visual or tactile surface quality of a material – the relative smoothness or roughness of the surface.  Texture refers to the quality of a surface as perceived directly by touch (tactile texture) or indirectly by the eye (visual texture).  Texture is produced by material, colour, line, relief and finish, and visual texture can also be produced by pattern.

Texture is the element is most often overlooked in design.  Uniformity of texture will produce a bland and unsatisfactory scheme, even when there is variation in colour, but a scheme based on a restrained palette of colours and materials can provide visual and tactile interest through diverse textures.

Texture is used in a broad sense to cover the properties of solidity, reflectivity, translucency and transparency (Dodsworth, p.133).


A tint is a light colour tone produced by mixing a chromatic colour with white or light grey.

Traffic Flow

See Circulation

Transitional Style

A contemporary blend of traditional and contemporary style, midway between ornate traditional and stark modern lines, equating to a clean, classic timeless design.  Also known as ‘updated classic style’ or ‘classic with a contemporary twist’.


See Function


Vibration is a visual distortion that can occur when vivid contrasting colours are placed adjacent to one another.  Since the eye interprets some colours as closer than others – warm (advancing) hues are perceived to be closer than cool (receding) ones – the eye cannot focus sharply on bright red and bright green if they are adjacent.  The lines where vivid contrasting colours meet will appear blurred and the colours themselves may appear to vibrate.  This distorting effect may account for the sense of disharmony and discomfort produced by colour schemes that juxtapose strongly contrasting colours.

Warm Colours

Colour near the red end of the spectrum are designated as warm.   Red, orange and yellow are warm colours.  Greys and other neutrals may be warm or cool, according to their content of warm or cool chromatic colour.

Working Drawings

Also known as ‘Construction Drawings’.   Final and detailed drawings: plans; elevations, sections and details accompanied by drawing notes necessary for the construction of the design.

Working Triangle


Areas that have a similar function or accommodate similar activities, such as work zones, dining zones, study zones, private zones and storage zones.


Involves designating space and allowance for specific types of uses and activities.


Dodsworth, Simon (2016) The Fundamentals of Interior Design (2nd ed.)
Nielson, Karla and David Taylor (1994) Interiors: An Introduction (2nd ed.)
Nissen, LuAnn, Ray Faulkner and Sarah Faulkner (1994) Inside Today’s Home (6th ed.)
Pile, John (1997) Colour in Interior Design

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