Light is one of the key elements of interior design. Most interior spaces constructed in the 20th century are used as much with artificial light as with daylight; because of this lighting has become a very significant tool for the interior designer. There are three major aspects to lighting: function, aesthetics, and health. The latter factor is often ignored, but insufficient illumination can cause eyestrain and physical discomfort. Illuminating engineers have established recommended standards of illumination for various tasks and have also provided rules and standards relating to brightness of the source of lighting and controls for shielding the eye from direct glare. Light can be diffused and can, in general, be controlled very accurately.

Two basic types of lighting are used in modern interiors: incandescent and fluorescent. The former is somewhat redder than daylight but contains all colours of the spectrum. Since fluorescent light has an uneven spectrum, colours tend to appear distorted. A mixture of the two is often the best way to achieve colour accuracy. Some of today’s fluorescent lamps are close to daylight accuracy, and manufacturers continue to improve the quality of available lamps. Both types of light can be used in “direct” or “indirect” lighting in interiors or in a combination of these methods known as semidirect or semi-indirect.

Designers and architects strive to build in lighting as much as possible. Recessed lighting, lighting coves, and architectural lighting in general can be controlled much more efficiently than portable lamps.

A good lighting scheme must provide some variety in highlights, shadows, and accent lights to avoid monotony. An even, overall lighting system, such as a luminous ceiling, can be highly efficient, but it lacks character and interest. Most interiors require a certain flexibility for different functions within the space at different times of day and night. In certain interiors, such as stores and shops, lighting becomes a display and sales tool, and in festive spaces, such as ballrooms or theatres, the quality of light can provide sparkle and mood more effectively than any other component of design. One can think of the potential of lighting in terms of the theatre. Some productions are staged without formal sets, yet the changing mood and setting can be suggested by controlled illumination.

Most intimate interiors depend to some extent on portable or fixed (ceiling and wall-mounted) lamps. The design of lamps, especially table lamps for homes, has somehow brought forth a vast array of bad designs, together with a smaller number of good ones. Many lampshades are similarly banal in design, but a shade as such is an excellent diffusor of light and shield against glare. Some lamps and shades are designed for specific tasks, others for accent lighting.

Fabrics

There are three basic aspects that determine appearance and suitability of fabrics for interior use: fibre content, weave, and pattern. Fibres are either natural or man-made. The important natural fibres are cotton, wool, linen, and silk. Although silk has long been considered the most elegant and desirable of all natural fibres, it does not stand up well under direct sunlight and heat and, in general, requires more care than most other fibres. Wool, like silk, is an animal fibre; depending upon its weave, it can be made into extremely strong and beautiful fabrics and is therefore very much in demand for contemporary interiors. Both cotton and linen are made from vegetable fibres and are both durable and pliable. Unless cotton and linen are interwoven with other fibres, however, they are not generally as strong as wools or man-made fibres and tend to be restricted to light-duty interior purposes.

Man-made (synthetic) fibres in the 20th century abound under a variety of trade names, and new synthetics are continuously being developed. Some of the major families of synthetic fibres are glass fibres, acetate, acrylic and modacrylic, nylon, olefin, polyester, rayon, and saran. The chemical composition and processes used in the manufacture of man-made fibres make possible a variety of specific qualities. Some offer strength and elasticity; some offer resistance to fire, stain, mildew, sun, or abrasion; and some offer resistance to moisture and organic agents, others to crushing and wrinkling.

Many fabrics are woven in a combination of two or more fibres in an attempt to improve the appearance or utility or both. Another factor in selecting or specifying fabrics is the touch of the fabric, or the “hand.” Certain fabrics made from man-made fibres seem unpleasant to the touch compared to silk or wool fabrics.

Weaving is an ancient art, and fundamentally there is little difference between the very early handlooms and the power looms found in major textile plants today. The three most common weaves in use are plain weaves, which include basket weaves; floating weaves, which include twill and satin weaves; and pile weaves, which include both cut and uncut weaves. Weaving techniques of lesser importance to interior design include knitting, twisting, forming, and felting.

The pattern of textiles, especially in contemporary terms, is frequently the natural pattern created by the weave of the fabric, although patterns are also created by printing. In traditional textile terms, reference to pattern usually meant a historic style. The history of textiles ranges from early Egyptian and Oriental patterns to the present. Each era has developed fashionable and popular patterns. Contemporary textile designs, for instance, are usually abstract or geometric, but floral and large flowing patterns were also popular in the 20th century.

Colour is one of the most important aspects of fabrics in interior design, inasmuch as the colours of fabrics are frequently the most important areas of colour in interiors. Dye colours can be added to unspun fibres, spun yarns, or woven textiles. Colour fastness is a major concern to interior designers, for faded fabrics can be quite detrimental to an interior.

Natural elements

No man-made object can equal the beauty found in nature, and it is not surprising that the introduction of natural elements into interiors has always been considered desirable. In spite of their beauty, one cannot arbitrarily introduce a plant, a tree, or rocks, or water into an interior. The foremost considerations must be the location of the space, its climate, and its relationship to the outdoors.

Climatic considerations determine the kind of plant, flower, or tree that can prosper in an interior. The most beautiful plant will not survive long under adverse conditions, and a dying tree or plant certainly offers no decorative advantage.

The location and orientation of interior to exterior spaces is another important consideration in the introduction of natural elements. In warmer climates, it is possible to have a gradual transition between interior and exterior, and plants providing this natural transition will look well and will prosper. In colder climates a real barrier of glass or a solid wall separates the indoors from outdoors, and at best the transition can be made visually.

There are a number of simple devices that make it possible to keep delicate plants and flowers alive under controlled conditions. Greenhouses in all sizes, ranging from window size to room size can be the most delightful areas of an interior, but obviously special conditions and maintenance must be provided. The scale of plants or small trees must be considered. One large indoor tree can be a beautiful accent in even a small space. Too many trees or plants in a small space would be overpowering, unless indeed the space is designed primarily as a greenhouse space or plant room.

Natural elements other than plants and flowers that can be used in interiors are water, rocks, stones, or pebbles, and planting areas in natural soil. For large spaces, usually public buildings, pools or contained areas of water can be extremely beautiful and exciting. Some interior features have been created with running water and small recirculated waterfalls. Sometimes a small area of pebbles with a few plants or carefully chosen rocks can add a touch of real beauty to an interior. Even collections of rocks, minerals, seashells, and other natural elements provide the touch of nature that can make an interior come alive.