Visual comfort

At that, our eyes should not get overstressed and tired. In order to achieve visual comfort, many lighting parameters must be complied with: optimum illumination, minimisation of the dazzling effect of lamps, harmony of distribution of light brightness on the main surfaces of premises, correctness of light transmission, formation of shadows etc.

Lighting fixtures and systems will help you to ensure all that. A good specialist, selecting, using and combining them with different components of the interior as regards style, colour and scale, will help to create not only comfortable light environment, but make the interior particularly unique. Practically all types of lighting fixtures consist of two main parts: the light source (lamp) and the lighting fittings (they redistribute the light from the lamp in space and sometimes even transform its properties). Based on their purpose, lighting fixtures are subdivided into six lighting categories: general, local, combined, decorative, orienting and exposition lighting fixtures.

Based on the type of installation, the following types of lighting fixtures are singled out: ceiling luminaires, pendant luminaires (hanging from the ceiling), built-in ones (in false ceilings), wall luminaires, floor lamps and table lamps. Our ability to discern small details of objects accurately considerably depends on the distribution of the light flux in space, which comes from the general lighting luminaire. The light distribution is evaluated based on the so-called curve of luminous intensity. The more it resembles an oval, elongated along the axis of the light flux, the narrower the curve is considered and the better is illumination in the centre of the light spot. The configuration of that curve is the most important parameter of a light source.

It is best to use lighting fixtures with a narrow light curve within premises with high ceilings. These light fixtures possess high contrast, directivity, clearly defined shadows; they are economical. They light predominantly horizontal surfaces. Light-colour interior decoration will make that type of lighting milder. Devices with mirror halogen lamps, installed on bus ducts, which are quite convenient, are often used for accentuated illumination of paintings, sculptures etc. Lighting fixtures with a medium light curve are used for general lighting with soft light transitions, sufficient light saturation, moderate contrast and well-balanced distribution of brightness within premises with normal ceiling height. Lighting fixtures with a wide light curve are more suitable for general lighting in premises with low ceilings and ensure good lighting of vertical and sloping surfaces; they ensure uniform distribution of light. Still, such lighting fixtures have low shielding angle, and they must be carefully installed in order to avoid the dazzling effect.

Where rays should be directed

The directivity of the light flux influences contrasts in the premises. Depending on the ratio of the light flux directed upwards to the light flux directed downwards, the following lighting fixtures are singled out:

• direct light fixtures (all or almost all light flux is directed downwards),
• diffused light fixtures (the light flux directed upwards is equal to the one directed downwards (like, for example, a crystal chandelier or open neon lamp situated horizontally),
• reflected light fixtures, when all or almost all light flux is reflected from the surface against which it is directed.

Direct light fixtures are suitable for premises with low ceilings. As a rule, these are usual luminaires attached to the ceiling or built into it (halogen, luminescent, neon, LED). These are economical for creating local lighting for reading or work or for the illumination of paintings, sculptures etc.

Diffused light fixtures have the highest efficiency and are suitable for general lighting. They are characterised by uniform distribution of the brightness of the light, which is reflected from the surfaces of walls, ceiling or floor. They possess mild shadow-forming properties and heightened light saturation, which is important for the creation of visual comfort. Still, if dark colours predominate in the colour scheme of the premises (especially those of the ceiling and walls), it is necessary to use brighter light sources (lamps).

Reflected light fixtures create the most comfortable and uniform lighting, fully complying with the regulations for the limitation of dazzling effect values and lack of comfort; they ensure good light saturation, combination with the upper or sideways daylight. In order to improve the economics of lighting, the decoration of the ceiling with the maximum reflectivity is necessary.

Light and space

The perception of the interior depends, basically, on the distribution of brightness and colour between the components of the interior decoration and objects. When we buy a nice-looking wall lamp that we like and hang it at a prominent spot or simple use a brighter bulb, the consequences could be unforeseeable, e.g., a person could become irritable, he could develop a headache; there could be other unpleasant consequences as well. The thing is that, by such simple actions, we could violate the complex interconnection of optical effects, which is taken into account by light designers. With a change in the brightness of light reflected from the floor, walls and ceiling, the visual perception of the proportions of premises is changed; that is why, by varying the brightness (intensity), one is able to correct the perceived visual volume of premises.

The dark ceiling seems to be lower, while the light one seems to be higher. If the floor colour is too light, the premises seem lower. A lighter wall at the end of a narrow corridor makes it visually wider. Warm colours make objects "nearer", e.g., a yellow wall seems to be nearer, while cold colours make objects look "farther away". In small premises, in order to widen the space visually and increase light saturation, it is necessary to increase the illumination intensity and use decorative materials with good reflectivity properties, while, in large premises, it is necessary to use the same method, but as regards the floor and ceiling. Windows, paintings and mirrors are instrumental in "widening" of space. One should not forget that the black colour makes premises "narrower", while the white colour makes them "wider". If, in narrow premises, the lighting is situated along the middle line of the ceiling, the room will seem even narrower. In order to “widen” it visually, it is necessary to situate the lighting along a line shifted towards one of the walls.

It is possible to single out functional zones in the premises not only by using partitions, but also by using linear light sources, which could be programmed for a certain disposition, sharpness, brightness or contrast.

Light and form

Light is able to "control" the configuration of objects, increase or decrease their expressivity. Our perception of the configuration of objects depends on the brightness of their separate surfaces and distribution of shadows formed on them. The main thing here is the correct selection of the direction of the directed light flux. If a voluminous object is uniformly lighted from all the sides, it could seem flat, since, with the diffused lighting, the volume is lost. The best result is achieved, if the diffused or reflected lighting is used in combination with straight directional light, but, if one works with such an object as the human face, having a deep, well-expressed relief, the role of soft diffused or reflected light is more important.

Using directional light, it is necessary to avoid the formation of undesirable shadows that are able to change the configuration of both the lighted and nearby objects, as well as the interior as a whole. If the lighting of a surface is not uniform, its separate areas are perceived as occurring at different levels. Making experiments with shadows, it is possible to create quite different light dynamics in premises.

Light and colour

If uniform illumination is achieved within the premises, a warm colour is perceived as being brighter than a cold one. If the surface of objects, walls etc. is painted dark, their texture will not be expressed well. An object looks darker against the bright background, and lighter – against the light background. Warm colours are advantageous if warm white incandescent and discharge lamps are used for lighting.

Light and colour comfort

Optical fatigue often becomes stronger, if there are abrupt changes in brightness. Still, very monotonous lighting is not a very good solution either. When saturated and different shade colours are used in the decoration, the optical fatigue increases. While decorating large areas, it is better to use colours with lower saturation.

Light and mood

It is well known that colour influences people emotionally. Red-orange colours are stimulating. Green — light blue colours create the impression of coolness and calm. White and black colours stress the solemnity and festive character of the environment. It should be taken into consideration that the perception of one and the same colour could considerably depend on the climate of the area, as well as on the human habits and taste.

Specialists’ opinions

It is difficult to ascertain, which luminaires should be used in this or that case. It is possible only to recommend to comply with the general rules of the lighting organisation. It is better to use general lighting luminaires in corridors and other premises, where the need in lighting is constant. As regards sitting-rooms, general and local lighting luminaires are used there (wherever necessary: at the coffee table, behind the TV set, in the recreation zone etc.). As regards bedrooms, darker warm light of the reflected light fixtures is more suitable there.

It is possible to place a dimmer lamp or a night lamp near the bed, on a bedside table; as regards pier glass, light fixtures with good colour transmission are suitable. As regards nurseries, both general and local lighting is necessary there. In kitchens, besides using the main lighting fixture with an incandescent lamp, the illumination of working zones, where food is prepared and where crockery is washed, is necessary.

Luminescent lamps with the power of up to 30 W are suitable for that purpose. Besides, small-size luminaires could be used for the illumination in cupboards, boxes and other furniture. In order to use both the artificial and natural lighting simultaneously, it is necessary to use luminescent luminaires situated separately, lighting panels, different decoration materials with a heightened reflectivity; it is possible to use luminescent luminaires of cold white and warm white colour as artificial light sources.