Key words: Psychic microclimate, light microclimate, illumination, color space, color, color perception, visual comfort

COLORS OF THE INTERNAL ENVIRONMENT

The color of the indoor environment can be expressed by:

• Surface color and light color
• Surface material
• Combination of colors on multicolored surfaces
• Size of spaces

INDOOR LIGHTING

Lighting can be divided in term of light sources:

• Daylight - natural, scattered light and direct sunlight
• Artificial lighting - artificial sources
• Combined lighting - Daylight illumination supplemented with artificial light

Daylighting is more appropriate for the human body than artificial lighting. Human biorhythm is also associated with regular alternation of light and darkness. The minimum level of daylighting, characterized daylight factor [%] must be ensured in residential buildings.

The criteria used to describe the light microclimate are:

• Daylight factor
• Illumination
• Temperature of chromaticity
• Color rendering index (CRI)
• Glare index

The light is a visible glow capable of inducing an immediate visual perception evaluated by normal human sight. The range of visible radiation is within the wavelength range from 380 to 780 nm.

The daylighting factor is the ratio of illumination at a point on a defined plane by a direct or reflected skylight at that time to a comparative illumination of the outer, unshaded horizontal plane under the assumed or known distribution of sky brightness.The contribution of direct sunlight to both light intensity is eliminated. The value of daylight factor is expressed as a percentage.

Light intensity (illumination) is a photometric quantity defined as the light flux incident to the surface unit. It is therefore the ratio of light flux (lumens) and area (m^₂).

COLOR OF THE SPACE

Visual perception of colors creates feelings of warmth and cold. Physiological functions, including basal metabolism, are accelerating due to warm colors. Conversely. The change also depends on the current psychological state. Green and blue are passive and cold-acting colors that support mental concentration and longer work performance. Heat-acting colors (red, orange or yellow) are dynamic stimulating colors.

Color is the property of light, or the substance from which the light comes out. Color expresses a perception that is created on the retina by visible electromagnetic radiation (waves).

The color perception depends on the spectral composition of the incoming light (dependence of light flux and frequency or wavelength) and its intensity relative to the background. Receptors called three-colored suppositories that are sensitive to three basic colors - red, green and blue, mediate color vision. All known colors are based on these three basic colors.

The color perceived by the eye can affect the feelings transmitted by the touch or muscular tension in the brain (the same objects may be considered lighter or heavier in terms of color). Color also influences the concept of space (The room may be optically enlarged or reduced, height increased or decreased) because the overall color of the environment generates feelings of volume or stiffness, or it is involved in these feelings. The research in 1977 found that warm colors have up to 0.4 °C shifted thermal comfort compared to cold colors.

Generally, black is about 25 times darker than white. If a 40-Watt light bulb is sufficient to illuminate a room with white walls, then we would need a 1000 W bulb for the same light perception in a room with black walls.

EFFECTS OF PSYCHIC AND LIGHT STRESS

Visual perception of the internal space is closely related to the central nervous system. Light microclimate encourages feelings of anger, excitement, or joy and serenity. The light microclimate is defined by the geometric dimensions of the space, the type of light sources, the number and layout of the luminaires, the uniformity of lighting, the color rendering and the contrast in space. Mental fatigue can be a consequence of all components of the environment on the human nervous system.

OPTIMIZATION OF PSYCHOLOGICAL AND LIGHT MICROCLIMATE

The color of environment and its components creates the overall psychological effect on the environment of the organism. There is no comprehensive optimization of light microclimate. The objective of optimizing the mental and light microclimate is to create a sense of visual comfort. Visual comfort (well—being) is the state of the organism, in which the visual system functions and in which one feels in light comfort.