1 quantity and quality of brightness
1. 1 brightness
12Â° field of view and other brightness curves The human eye perceives the spaciousness and comfort of the room by observing the brightness of the indoor light and the surface of the object. This subjective brightness perception, called brightness, is different from measurable physical brightness and is a perceptual quantity that includes psychophysical and physiological physical quantities. The International Commission on Illumination (CIE) recognizes and recommends the use of the empirical formula for brightness according to Bodmann et al. to quantify this perceived amount, ie in the 2Â° field of view non-color light (white light):
B= 22. 969L0. 31T - 22. 969 ( 0. 07186+ 0. 24481L 0. 31u) ( 1)
Where B is the apparent brightness (dimensionless), and LT, LU are the target and background test brightness, respectively. The 1 drawn according to this formula is an LT, LU related iso-optic brightness curve. The value in the curve is the equal-visual brightness B. LS is the lowest brightness value that the target cannot distinguish from the background. It is called â€œblack limitâ€. At this time, the brightness B=0. The LD G curve is the target for uncomfortable glare. The limit brightness value, called the "bright limit", and has L DG = 205L 0. 57u.
The brightness model can predict the actual situation of the light environment more ideally, and provides a reasonable basis for the treatment of indoor visual work lighting, decorative art lighting and background light and darkness, and provides control. An indoor method of uncomfortable glare and improved illumination visibility. Studies have shown that in visual workplaces, people are satisfied that the ambient brightness B value is within the range of 100 Â± 20. If the brightness of the background is lower than B=80 and the background wall brightness LU is in the range of 50 to 150 cd/m 2 , the target brightness LT can be calculated from (1) to be 120 to 150 cd/m2. In areas where reunion and entertainment are required, bright areas are required in the field of view, and the surface brightness should reach this level.
1. 2 light color brightness
2C is a constant iso-luminance curve. In an indoor environment, bright and vivid colors make people feel bright and help to express the bright feeling of the living room. CIE recommends using equivalent brightness to evaluate the difference in brightness due to differences in light color saturation under bright visual conditions. The empirical formula for converting physical brightness to equivalent brightness L eq in a 2Â° field of view is:
Leq= 10c( x, y)L( 2)
Where: L is the target physical brightness, cd/ m 2; x , y is the chromaticity coordinate of the color light; c( x, y ) = 0. 256 - 0.
184y- 2. 527xy+ 4. 656x 3y+ 4. 657xy 4.
2 is a color profile when the apparent brightness ratio L eq / L of the different color light and the reference white light (point E) drawn by reference < 8> is constant. As shown in the figure, in addition to the yellow-green light, the more saturated the color light, the brighter the color, especially the blue-violet light region, which is close to the saturation state, and the brightness can reach 1.7 times the reference white light. When the physical brightness of several typical color lights is 100 cd/m 2 , the equivalent brightness is calculated by the formula (2) as shown. It can be seen that improving indoor color saturation is an effective way to obtain a sense of brightness.
In the living room of the living room, people usually use the light and light color as the main illumination. The high chroma color is generally only used in the local decorative lighting. Therefore, the spatial color perception mainly comes from the reflected light of the larger interface material. According to the literature <9>, the high color rendering index (CRF) light source is used to improve the color saturation of the indoor interface. Even if the illumination in the room is as low as 25%, it still has the same brightness as the room with low color rendering index. In addition, the high correlated color temperature (CCT) source (5 000 K) is 30% higher than the 1 W 3 000 K source.
The XYC-I full digital colorimeter is used to measure the influence of several common light sources on the brightness of the swatch. The swatch test brightness is 100 cd/m2. When the color rendering index and color temperature of the light source are different, the swatch surface color The product coordinates and equivalent brightness calculation values â€‹â€‹are as shown. The data shows that using a light source with better color rendering and higher color temperature can make the material brighter, which is also an effective way to improve indoor brightness.
1 equivalent brightness of several typical color lights
2The influence of several common light sources on the brightness of the swatch
1. 3 brightness distribution
Since the difference between the visual and dark contrast of the viewing target and its background determines the subjective brightness, the condition of each brightness factor in the field of view - the brightness distribution controls the comfort of the human eye and the perception of space. In the living room, the person's field of vision is too bright, which is easy to cause glare; too much contrast between light and dark makes the eyes need to adapt continuously, and it is easy to cause visual fatigue, especially for the elderly who have a sharp decline in eye adjustment function. Too low brightness or brightness contrast can reduce the visual function and cause darkness. Therefore, the living room space needs to be handled to prevent a visual discomfort and provide a sufficient balance between visual light stimulation.
1. 3. 1 optimal brightness ratio in the field of view
In the living room, reading, talking, film and television entertainment and entertainment should have the best visual function, and the brightness of the field of view is optimally distributed. The Lighting Guide of the British Building Services Registration Association CIBSE LG11 and the North American Lighting Engineering Association all recommend that the brightness distribution ratio of the best field of view of the operation be 10:3:1, and the brightness ratio should not exceed 40:1 throughout the field of view. Therefore, the brightness distribution of each part of the living room can be designed with reference to 3.
3 living room brightness distribution with good visual effect
In order to provide a good balance of the brightness distribution in the field of view for the visual operation, the illumination standard specifies that the illuminance of the visual working surface and the surrounding surroundings shall not be lower than a certain value, and the illuminance ratio is 1.5:1. However, when the material reflectance difference When it is large, such as white paper and black matt tabletop, the brightness ratio under the same illumination reaches or exceeds 30:1, and long-term gaze can cause visual discomfort. Obviously, the brightness distribution in the field of view should take into account the actual effect of the surface reflectance. When the brightness ratio in the field of view is large and glare may occur, the LDG brightness limit curve in 1 may be used to verify or perform glare level evaluation. The lighting standard does not have a clear requirement for the uniform glare value of the house. The uniform glare level (U GR) limit value recommended by CIE can be used in the design. For example, a very good threshold value is 19, and the actual feeling is worse than 25 degrees.
1. 3. 2 brightness balance of space
Order is an important condition for facilitating visual cognition. The comfort of the spatial light environment requires a certain sense of order in the light and dark levels, and the sense of space must be distinct, so as to avoid confusion or dullness. The living area of â€‹â€‹the penthouse is generally large. Usually, the space is divided into several open functional partitions and transition spaces according to activities. The spatial composition is more complicated, and it is necessary to reasonably plan the brightness balance relationship of the space to obtain the comfort of the space impression. sense. The balance of brightness in the living room space can be considered from the following three aspects:
(1) The brightness of the living room space The space areas that need to be highlighted in the living room are the meeting area, the key decoration area and the foyer area, followed by the restaurants and stairs with interconnected spaces. The change in brightness of these areas contributes to visual extension, creating depth perception and increasing spatial sensation. The brightness gradient of adjacent areas generally does not exceed 3:1, and the brightness ratio of the entire space is controlled to not exceed 40:1. It is worth noting that the wall of the living room of the penthouse is towering, the interface of the enclosure and the facade of the furniture are in the field of view. The proportion of the surface is the largest, and the information such as the brightness, color, structure and mechanism of these surfaces frequently stimulates people's visual movements, and has the greatest impact on people's sense of space, comfort and face-to-face communication. ISO Standard 9241-6 (ISO, 2000) suggests that vertical illumination plays an important role in the impression of room depth. The illuminance of the vertical surface is usually increased and the depth of field impression can be increased. Therefore, to create a brightness order of the living room space should focus on the brightness distribution of the vertical surface.
(2) Improve the brightness within 40Â° of the horizontal line of sight. In the leisure living space, people prefer a certain degree of â€œbright visionâ€ and â€œvisual interestâ€ center. The bright vision comes from the average brightness in the field of view, and can also be experienced from the brilliance of the luminaires and the reflection of the decoration; the visual interest needs to deal with the lighting pattern, the space interface styling, the material and the light and color. A certain brightness contrast is achieved. Research by Loe et al. on indoor lighting has shown that brightness in the 40Â° horizontal line of sight is the most important area for determining brightness. The room is rated as â€œbrightâ€ and the average brightness of this range needs to be at least 30 cd/a. The ratio of the maximum to the minimum brightness that can cause visual interest needs to reach 13:1. According to this calculation, a living room of 5.8 m Ã— 8.2 m is calculated according to a viewing distance of 6 m and a height of 1. 7 m. The average brightness of the wall should be at least 30 cd/m2 below 3. 8 m. As for the "theme wall" that needs to be highlighted in the living room, the best brightness ratio should be achieved. Consider the optimal brightness of the wall recommended by the data, take the lower limit Lmin = 50 cd/ m2, and the upper limit is Lmax = 13Lmin = 650 cd/ m2. For the white latex paint wall, the reflectance ratio = 0. 8. According to the diffuse reflection formula E= L / , can calculate the vertical illumination EVâ‰ˆ2 550 lx of the highlight area of â€‹â€‹the wall. The brightness of the area is calculated as B= 151 by the formula (1). At this time, the human eye feels bright but does not feel glare. .
(3) Choose a reasonable ceiling brightness. The ceiling of the living room is generally higher (usually above 5 m). The ceiling brightness is mainly the first impression that affects the visitors' perception of space. The bright ceiling helps to highlight the height of the space. It has become the preferred solution for many residents due to its association with â€œfashionableâ€. The ceiling brightness recommendation value 21 is 100-400 cd/m2. In fact, since the ceiling height exceeds the horizontal field of view of the person in the bottom layer, the continuous effect of this height sense is significantly more affected than the â€œsleek senseâ€ of the indoor faÃ§ade factor. Much smaller, excessive pursuit of ceiling lighting is not conducive to energy saving, and may also have a serious visual impact on personnel activities in the mezzanine walkway. When the ceiling of the living room is provided with a suspended ceiling, the height of the interlayer is generally about 2. 5 m, which is close to the human eye, and the field of view is large. The excessive brightness of the lamps and the ceiling surface is likely to cause visual discomfort and glare.
2 comfortable brightness requirements for lighting design
The lighting design is an important part of achieving the quantity and quality requirements of the living room brightness. The high-ceilinged living room of the penthouse house is different from the single-storey house with a normal floor height of 3 m. It is difficult to achieve the above-mentioned satisfactory brightness distribution simply by increasing the power or the number of lamps. It needs to be based on the structural characteristics of the living space. And decoration requirements, reasonable choice of lighting solutions, lighting methods and light sources and lamps. When designing, the following points should be considered:
(1) Formulating a multi-purpose lighting scheme The family living room generally needs to meet the multi-functional living needs, such as gatherings and entertainments of friends and family, and needs a bright and happy light environment to set the atmosphere, the overall lighting requirements are the highest, and the overall brightness should be at an optimal state. When watching TV, reading or rest, you need a quiet and warm atmosphere, requiring the ambient light to be dark, and the overall brightness should be appropriately reduced. To this end, it is necessary to design different lighting combinations, lighting control by setting group lighting or dimming.
(2) Choosing a reasonable lighting method The living room ceiling of the penthouse type is higher. When the ceiling lamp, chandelier or downlight installed in the ceiling is used to illuminate the entire space, the change in illumination height follows the inverse square law of distance. The lighting in the lower part of the living room usually does not reach 1/3 of the top illumination. For example, the illuminating ceiling, the ceiling light trough and the chandelier with the shading astigmatism on the bottom, these indirect lighting methods are very obvious for the bright ceiling, while the lower lighting effect is Very limited. Therefore, the lower part of the living room needs to add local lighting or accent lighting, such as wall lamps, floor lamps or table lamps, to ensure the brightness level of the human eye in the bottom space. Generally, the living room has a large lighting window on the outer wall. When there is no curtain covering at night, the luminous flux is seriously lost. The window area is prone to dim feeling. It is also necessary to consider adding some bright elements, such as setting decorative lighting or adopting high. Reflective, high-color decorations to brighten.
(3) The choice of light source and luminaire should be installed. The structure of the luminaire determines the redistribution of the radiant light of the light source. The light distribution form of the luminaire, the brightness of the light exit, the efficiency and utilization factor, and the installation position of the luminaire all directly affect the lighting environment. The brightness distribution. For example, when the living room chandelier is used as general illumination, its power is high and the surface brightness is high. The suspension height is within the eye level of the mezzanine aisle. It is necessary to control the glare. The chandelier should be equipped with upper and lower light distribution type lamps. The ceiling uses a wide-lighted in-line downlight to illuminate the four walls, and on the side of the mezzanine aisle, narrow light distribution should be considered.
In addition to meeting the illuminating function, the requirements for the light source include light color, color temperature and color rendering index. Since people's hobbies about light color are related to the level of illumination, the choice of light color and color temperature should be considered in harmony with environmental atmosphere, interior decoration and furnishings. In the living room, the general illumination is mostly white or warm white, which is close to the natural light color. For the decorative lighting to create the mood, the color light can be used to improve the brightness of the light color; local lighting and accent lighting should try to select the light source with excellent color rendering index ( Raâ‰¥80).
3 brightness design method application examples
The following is a lighting case of a villa living room. The design goal is to create a â€œbright and brightâ€ visual space, that is, within the horizontal field of view, the average brightness of the main wall in each area of â€‹â€‹the living room reaches 30 cd/m2, and the brightness at the highlight reaches 100Â±. The satisfaction level of 20, and the brightness distribution of the space is designed according to the above ratio. In the design, the German lighting calculation software DIALux4.2 was used for simulation analysis. Some data and analysis are as follows:
(1) 3 is the floor plan of the living room lighting fixtures. The living area of â€‹â€‹the living room is calculated to be 114.29 m2 (including the mezzanine floor area), the ceiling of the ceiling is 5.30 m high, and the maintenance system is taken to be 0. 80.
(2) 4 is a list of lamps. In the actual project, the specifications and styles of the illuminator and the light source are selected as much as possible according to the design scheme.
4 list of lamps
(3) 4 is the comparison between the calculated value of the spatial surface brightness and the measured value. The measured brightness value is measured at the random point in the center of the living room. Due to the differences in the actual use of lamps, decorative materials, space modeling and furniture furnishings and design schemes, there is a certain deviation in the contrast data, in which the specular reflection brightness deviation of glass, metal and paint often exceeds Â±10%. After actual measurement, in the scene The brightness B value of each highlight surface is about: ceiling 79, decorative painting 85, TV background wall 95, sofa table lamp area 90, wall lamp wall 82 in the hall, and 115 ceilings in the restaurant. The brightness level and brightness distribution of the key lighting areas in the field of view basically reach the design goal. If you consider the high-light reflection of lamps and decorations, the actual brightness will increase.
(4) In the actual scene, there is no glare in the bottom area of â€‹â€‹the living room. In the south direction of the mezzanine aisle, the light from the wall lamp (up and down) of the entrance hall area is slightly uncomfortable and glare, corresponding to the calculation result in the middle. .
(5) In terms of lighting energy saving, according to the indoor lighting measurement method (GB 5700-85), the average illuminance of the effective working surface of the living room is 197 lx (take a 1 m square grid), and the illumination power density value is 10.98 W/ m2. , equivalent to 5. 57 W / m2 / 100 lx, lower than the target value of residential lighting power density of 6 W / m2 in the lighting standard, energy saving effect is good. The lighting power density value is lower if calculated according to the area per household as specified in the standard. It can be seen that through the brightness design and quantitative calculation, it can effectively deal with the problem of satisfying the relationship between visual comfort and energy saving in residential lighting.
The focus of residential indoor lighting is to obtain a visually satisfactory light environment. The quantity and quality of brightness in the field of view determine the quality and effect of the spatial light environment. Therefore, brightness should be an important indicator for the design of indoor light environment. The analysis of the quantity and quality of brightness, the brightness distribution and the design examples in the living room lighting of the penthouse shows that the brightness design method is essentially based on the theory of light and color vision, which is directly oriented to the subjective visual experience. Design method. The method is based on the principle of satisfying the subjective needs of the user's physiology and psychology. In addition to meeting the basic requirements of light energy distribution, the design content emphasizes the use of the brightness parameter to deal with the brightness ratio and balance of each component of the space. The relationship is to optimize the shape design of the indoor space; in the design procedure, the first is to deal with the relationship between the brightness perception and the physical quantity to determine the brightness value of the space and its distribution state. In terms of design methods, due to the traditional calculation methods with illuminance values, such as point-by-point calculation method, utilization coefficient method and unit capacity method, there are limitations and applications in the case of complex spatial structure and many types of lamps. Sexual problems, design results and actual situation errors are large, therefore, in the actual project can use lighting calculation software to assist the design, making the brightness design and judgment more accurate. In addition, the comfortable brightness "related to the more complex problems of ethnic habits, psychological factors, environmental conditions, etc.", in the residential lighting design process, should be people-oriented, fully consider the customer's brightness preferences.
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