In office buildings, the indoor light environment is a crucial factor in evaluating the comfort of the indoor environment, especially in the office, drawing room and other types of rooms, mostly used for copywriting work, rooms with high requirements for the light environment in the room. . The natural lighting of office buildings has a certain effect on satisfying people's physiology and psychology. In recent years, researchers have discovered the importance of sunlight for people, especially indoor natural lighting has an irreplaceable role in ensuring the circadian rhythm of human health. In addition, the researchers found that natural light can effectively help office workers reduce eye visual fatigue and improve work efficiency to a certain extent. It can be seen that natural light has its own advantages in terms of comfort that artificial lighting cannot match, and it also plays an important role in reducing the energy consumption of architectural lighting in terms of economy. Therefore, if natural lighting can be utilized efficiently, it is very advantageous for the transformation of the existing office building light environment. Through a one-week research and test on the light environment of existing office buildings, this paper elaborates on the window opening mode, illuminance distribution and surface reflectivity of the office. The data processing and analysis determine the existing building light environment. Whether the relevant parameters meet the requirements of the specification, find existing optical environment problems, provide a quantitative basis for technical screening, and propose specific technical strategies and recommendations for green transformation.
Light environment research program
1.1 Research on the selection of office buildings<br> The existing office buildings in this survey are mainly office buildings, and can represent existing office buildings with earlier construction time. The transformation of the light environment in such office buildings is necessary and feasible. The window opening of this type of office building is mainly composed of traditional strip windows. There are a few glass curtain walls in part. The rooms are distributed on the north and south sides of the corridor. The typical office is mainly office, and there are also a certain number of open offices. The office is not much deeper from north to south, most of them are 6-8m. Some office buildings are the same as the north and south, while some north office offices are slightly smaller. A schematic diagram of a typical research office building is shown in Figure 1.
The sample selection is mainly within the scope of Tianjin University and Nankai University, and the multi-storey office building (party and government office, scientific research building) of the board, a total of 16 office buildings, respectively sampling the office of the north, south and north, mainly investigating the window opening in the standard layer. Relevant data such as the illuminance of the working surface, the reflectivity of each surface material, the transmittance of the transparent envelope structure, and the subjective feelings of the office staff.
1.2 Research content and test methods
1.2.1 Office size and window opening form The basic dimensions of the office, including the room opening, depth and height, height and other basic data. The research content in the form of window opening includes basic data such as the number of windows in the room, the basic size of the window, the size of the opening fan, the height of the window sill, and the width of the window. The relevant parameters are the conclusions of the later research conclusions, providing a true and reliable data basis.
1.2.2 Measurement of the illuminance value of the indoor working surface of the office Select the typical or open office of the four-way southeast and northwest of the standard floor in the office building, and measure the 0.75m respectively along the three axes of the window center line, the window wall or the side wall. High working surface illumination value, the specific measurement point is shown in Figure 2.
1.2.3 The surface reflectance of each material includes the reflectivity of different ground and wall materials. The illuminance value received by the surface and the reflected illuminance value are tested using an illuminometer. The receiver of the illuminometer is placed close to a certain position of the surface to be measured, and the incident illuminance ER is measured, and then the photosensitive surface of the receiver is aligned with the original position of the same measured surface, and gradually shifts away, and after the illuminance value is stabilized, the reading is performed. Take the reflection illuminance Ef, the measurement diagram is shown in Figure 3. Reflectance ratio is .
1.2.4 Transmittance of Transparent Envelope Structure When measuring the transmittance of the lighting material by the illuminometer, in the case of diffusing light in the sky, the receiver of the illuminometer is respectively attached to the inner and outer sides of the light-transmitting material of the window to be tested. The two measuring points should be on the same axis. Read the illuminance values ​​of the inner and outer measuring points separately, as shown in Figure 4. En is the internal measurement point illuminance value, Ew is the external measurement point illuminance value, and the transmittance
1.2.5 Corridor and public activity space illuminance measurement The horizontal illuminance of corridors and public spaces. If there are natural lighting windows on both sides of the corridor, the indoor natural lighting curve in the corridor area can be measured in the same way.
1.2.6 Subjective research section Through the combination of questionnaires and on-site inquiry, the existing problems of the architectural light environment and the use of usual blinds are investigated. And statistics office staff satisfaction with the indoor light environment, including the intensity of indoor light, whether there is glare effect.
Data analysis and existing problems
2.1 Insufficient lighting in the north office <br> In the process of investigation, after testing and data integration analysis, we found that the north lighting of the office building is generally insufficient, the illumination is low, and it needs to be turned on all day. 2.1.1 Selection of survey data From the 16 typical office buildings surveyed, we selected the data of two office buildings for analysis. The test site is selected from the office building of the School of Management and the School of Mechanical Engineering of Tianjin University. The layout of the measuring points is shown in Figure 5 and Figure 6. The test date is January 10th and January 9th, 2014. During the two days of testing, the weather was cloudy and the outdoor illumination was around 7000lx. The test was carried out once at 10:00 and 15:00. There was a large difference in the indoor illumination between the morning and the afternoon. The main reason for the analysis was the change of the outdoor illumination due to the change of cloud amount. The survey mainly tests the illuminance values ​​of each point in the room, analyzes the illuminance of the two offices separately, and compares the effects of single windows and double windows on the office light environment.
2.1.2 Survey data analysis According to the survey data, the office illumination distribution curve is drawn. We found that the illumination of the northbound room of the office building office is obviously insufficient (see Figure 7). The curve trend in the morning and afternoon is basically the same. The morning illumination value is generally larger than the afternoon. The value of the illuminance is attenuated faster when the distance is about 1 m from the window. Most areas can not meet the relevant provisions of the building lighting design standards (see Table 1 for details). Tianjin belongs to the Class III light climate zone. The side window lighting requires the working surface illumination to reach 450lx, and it is basically necessary to turn on the lights throughout the working hours to meet the requirements. Work for the need for light.
2.2 The problem of uniformity of lighting in the office of the deep-depth office <br> In the investigation, we found that the depth of the room is too large, resulting in uneven illumination from the room, and as the distance from the window increases, the illuminance value decays quickly, resulting in a shorter distance. , there is a large difference in illuminance value, which is easy to cause discomfort and glare. In order to explore the attenuation law of illuminance value with distance and quantify the uniformity of lighting in the office, the research and test were carried out.
2.2.1 Selection of survey data After the test and the analysis of the data, we found that the uniformity of illumination in the office building is generally problematic, especially the test samples with east-west office. In the existing office buildings, the depth of the east-west office is generally larger than that of the north-south office. Therefore, the problem of such offices is more prominent in the problem of uneven illumination. Therefore, in the data processing, the test data of the west office of the administrative office building and the east office of the mechanical school office building were selected as typical representatives of such data. The test is performed once at 10:00 and 15:00, and the measurement points are arranged as shown in Figure 8 and Figure 9.
2.2.2 Analysis of survey data It can be seen from the survey data processing that the illumination of the west office is higher than that of the afternoon, while the illumination of the eastward room is significantly higher than that of the afternoon, but the attenuation law is consistent. The position data attenuation of the center line of the window is very large, and it decays rapidly from the window. At about 1.5m from the window, the ratio to the outdoor illumination is attenuated to only 1/5 or even lower at the window (see Figure 10). .
2.3 South-facing window glare problem <br> During the investigation, we found that the south-facing room window generally has the problems of excessive illumination and window glare. Basically, the inner sunshade is needed to make the room reach a comfortable light environment, otherwise it is very It is easy to produce local glare. Therefore, in the investigation process, we also conducted a subjective questionnaire survey on the glare problem of the office environment. The results of the questionnaire show that in addition to a certain degree of glare in the south, there are certain bright spots or dazzling light in the northward room. This phenomenon is very common in office buildings and requires a part of the transformation. The survey used questionnaires and on-site questions and answers to investigate the satisfaction of office workers with the light environment in the office. The content includes a feeling of lightness and darkness, and a feeling of discomfort or glare. The results of the questionnaire (Figure 11) show that in the survey of the overall perception of the indoor light environment, the number of people who think that the overall light environment is moderate is only 36%, and the satisfaction is not high. Secondly, the overall environment is slightly dim and slightly dazzling. The total number is 55%, and the number of people who think that they are slightly dim is slightly more than the number of people who think it is slightly dazzling. In the investigation of the glare problem in the office light environment, the number of people who think that there is glare in the office accounted for 17%. Among them, in the survey of the south office, the number of people who believed that there was glare accounted for 28%, which was significantly higher than the north. The number of people who believe that glare is present in the office survey is only 6%.
2.4 Unreasonable selection and arrangement of lamps <br> In the investigation, in addition to measuring the illumination when turning off the lights, the usage status at the time of normal lighting was also measured. It was found that even with the addition of artificial lighting, the illumination level of the working surface in some places remains the same. Unable to reach the value specified in the specification. Through the investigation, it is possible to grasp the specific room type in which the illuminance of the luminaire is insufficient, and provide a basis for the design of the interior lighting improvement.
2.4.1 Selection of survey data After the addition of artificial lighting, the office where the lighting still fails to meet the requirements is mainly located in the north direction. The experimental data selected the north office of the office building of the School of Mechanical Engineering and the office building of the School of Management. Both samples belong to the typical open office. There are two side windows in the north facing room. The room area is (40-50) m2, and 4 rooms are evenly arranged. Fluorescent tube (T8), the office has 7-8 staff members. The measurement time is 10:00 and 15:00, and the measurement points are arranged as shown in Fig. 12 and Fig. 13.
2.4.2 Analysis of survey data Through data analysis, it can be found that after the artificial illumination is added, the uniformity of illumination is alleviated, but after 2.5m from the window, the illumination value will still decay to below 300lx, the lowest place. Under artificial lighting, it is only about 100lx. The "Architectural Lighting Design Standards" GB50034-2013 specifies the lighting power of office buildings and the corresponding required illuminance values ​​(Table 2). It can be seen that although some offices have artificial lighting attached, they still cannot meet the illuminance values ​​required by the specification, which is very unfavorable for those who work in this environment for a long time. Therefore, efficient lighting fixtures, reasonable lighting layout, etc. have an important role in the improvement of indoor light environment.
Suggestions for Improvement
Suggestions for the lack of daylighting in the north are as follows:
1) The window area on the north side can be appropriately increased or the reflectivity of each surface in the room can be increased, and a larger amount of light can be obtained, and the limited light in the room can be uniformly diffused to improve the brightness of the room;
2) Partially cooperate with effective daytime lighting to provide sufficient and stable light for the room;
3) Use the south façade of the adjacent north side building to set up some reflectors. Adjusting the angle of the reflector allows the light to enter the office from the north side, especially for the lower office in the north. However, this method has a large limitation, and it is necessary to have an office building adjacent to the north side, and a better improvement effect can be achieved only when the floor spacing is appropriate.
Suggestions for the uniformity of illumination in the office space of Dajinshen are as follows:
1) Using the lighting shelf, the lighting inside the room with large depth can be solved to some extent (see Figure 15). In order to increase the uniformity of illumination in the room, there is no exit downwards in a distance close to the window, and the exit of the light is opened inside the room, so that the illumination near the window is not further increased.
2) Using a reflective high window structure (see Figure 16), a set of specular reflection devices are installed at the top of the window. When the sunlight hits the reflective surface, it is reflected once to reach the ceiling inside the room, and is reflected by the diffuse reflection of the ceiling. Inside the room. The high reflection window increases the uniformity of illumination and illumination throughout the room.
Suggestions for window glare are as follows:
1) Reduce the brightness of the window. The brightness of the window can be reduced by using internal and external shading to reduce the influence of uncomfortable glare.
2) The use of reflective high window structure can also reduce the entry of direct sunlight, reduce the effects of direct glare and ground reflection glare, while increasing the background brightness of the entire room and reducing the impact of uncomfortable glare.
Suggestions for office artificial lighting are as follows:
1) Improve the efficiency of the light source. In the office lighting design, double-ended straight tube fluorescent lamps are often used. Added "T8 and T5 high frequency fluorescent lamps" products. Due to the improvement of technology, the light efficiency of the light source product is increased by about 10% to 20% compared with the conventional three primary color light source.
2) Improve the efficiency of the luminaire. The use of new grille luminaires, under the premise of meeting glare, reduces the unnecessary grid area, thus improving the efficiency of the entire luminaire, reaching more than 70%.
3) Reasonably arrange the position of the luminaire. The arrangement direction of the straight tube fluorescent lamp should be parallel to the person's main line of sight, generally perpendicular to the window, which can effectively alleviate the problem of uniformity of illumination.
summary
Through the investigation and study of the light environment of 16 office buildings near Tianjin University, it is found that there are still many problems in the light environment of the office, such as: insufficient amount of light in the north direction, uniformity of lighting in the office, large-direction window glare, and office labor. Lighting fixture efficiency, lighting layout and other issues. In response to the different problems found in the survey, this paper proposes corresponding transformation proposals to provide strong support for creating a good office space indoor light environment.
Light environment research program
1.1 Research on the selection of office buildings<br> The existing office buildings in this survey are mainly office buildings, and can represent existing office buildings with earlier construction time. The transformation of the light environment in such office buildings is necessary and feasible. The window opening of this type of office building is mainly composed of traditional strip windows. There are a few glass curtain walls in part. The rooms are distributed on the north and south sides of the corridor. The typical office is mainly office, and there are also a certain number of open offices. The office is not much deeper from north to south, most of them are 6-8m. Some office buildings are the same as the north and south, while some north office offices are slightly smaller. A schematic diagram of a typical research office building is shown in Figure 1.
The sample selection is mainly within the scope of Tianjin University and Nankai University, and the multi-storey office building (party and government office, scientific research building) of the board, a total of 16 office buildings, respectively sampling the office of the north, south and north, mainly investigating the window opening in the standard layer. Relevant data such as the illuminance of the working surface, the reflectivity of each surface material, the transmittance of the transparent envelope structure, and the subjective feelings of the office staff.
1.2 Research content and test methods
1.2.1 Office size and window opening form The basic dimensions of the office, including the room opening, depth and height, height and other basic data. The research content in the form of window opening includes basic data such as the number of windows in the room, the basic size of the window, the size of the opening fan, the height of the window sill, and the width of the window. The relevant parameters are the conclusions of the later research conclusions, providing a true and reliable data basis.
1.2.2 Measurement of the illuminance value of the indoor working surface of the office Select the typical or open office of the four-way southeast and northwest of the standard floor in the office building, and measure the 0.75m respectively along the three axes of the window center line, the window wall or the side wall. High working surface illumination value, the specific measurement point is shown in Figure 2.
1.2.3 The surface reflectance of each material includes the reflectivity of different ground and wall materials. The illuminance value received by the surface and the reflected illuminance value are tested using an illuminometer. The receiver of the illuminometer is placed close to a certain position of the surface to be measured, and the incident illuminance ER is measured, and then the photosensitive surface of the receiver is aligned with the original position of the same measured surface, and gradually shifts away, and after the illuminance value is stabilized, the reading is performed. Take the reflection illuminance Ef, the measurement diagram is shown in Figure 3. Reflectance ratio is
. 1.2.4 Transmittance of Transparent Envelope Structure When measuring the transmittance of the lighting material by the illuminometer, in the case of diffusing light in the sky, the receiver of the illuminometer is respectively attached to the inner and outer sides of the light-transmitting material of the window to be tested. The two measuring points should be on the same axis. Read the illuminance values ​​of the inner and outer measuring points separately, as shown in Figure 4. En is the internal measurement point illuminance value, Ew is the external measurement point illuminance value, and the transmittance
1.2.5 Corridor and public activity space illuminance measurement The horizontal illuminance of corridors and public spaces. If there are natural lighting windows on both sides of the corridor, the indoor natural lighting curve in the corridor area can be measured in the same way.
1.2.6 Subjective research section Through the combination of questionnaires and on-site inquiry, the existing problems of the architectural light environment and the use of usual blinds are investigated. And statistics office staff satisfaction with the indoor light environment, including the intensity of indoor light, whether there is glare effect.
Data analysis and existing problems
2.1 Insufficient lighting in the north office <br> In the process of investigation, after testing and data integration analysis, we found that the north lighting of the office building is generally insufficient, the illumination is low, and it needs to be turned on all day. 2.1.1 Selection of survey data From the 16 typical office buildings surveyed, we selected the data of two office buildings for analysis. The test site is selected from the office building of the School of Management and the School of Mechanical Engineering of Tianjin University. The layout of the measuring points is shown in Figure 5 and Figure 6. The test date is January 10th and January 9th, 2014. During the two days of testing, the weather was cloudy and the outdoor illumination was around 7000lx. The test was carried out once at 10:00 and 15:00. There was a large difference in the indoor illumination between the morning and the afternoon. The main reason for the analysis was the change of the outdoor illumination due to the change of cloud amount. The survey mainly tests the illuminance values ​​of each point in the room, analyzes the illuminance of the two offices separately, and compares the effects of single windows and double windows on the office light environment.
2.1.2 Survey data analysis According to the survey data, the office illumination distribution curve is drawn. We found that the illumination of the northbound room of the office building office is obviously insufficient (see Figure 7). The curve trend in the morning and afternoon is basically the same. The morning illumination value is generally larger than the afternoon. The value of the illuminance is attenuated faster when the distance is about 1 m from the window. Most areas can not meet the relevant provisions of the building lighting design standards (see Table 1 for details). Tianjin belongs to the Class III light climate zone. The side window lighting requires the working surface illumination to reach 450lx, and it is basically necessary to turn on the lights throughout the working hours to meet the requirements. Work for the need for light.
2.2 The problem of uniformity of lighting in the office of the deep-depth office <br> In the investigation, we found that the depth of the room is too large, resulting in uneven illumination from the room, and as the distance from the window increases, the illuminance value decays quickly, resulting in a shorter distance. , there is a large difference in illuminance value, which is easy to cause discomfort and glare. In order to explore the attenuation law of illuminance value with distance and quantify the uniformity of lighting in the office, the research and test were carried out.
2.2.1 Selection of survey data After the test and the analysis of the data, we found that the uniformity of illumination in the office building is generally problematic, especially the test samples with east-west office. In the existing office buildings, the depth of the east-west office is generally larger than that of the north-south office. Therefore, the problem of such offices is more prominent in the problem of uneven illumination. Therefore, in the data processing, the test data of the west office of the administrative office building and the east office of the mechanical school office building were selected as typical representatives of such data. The test is performed once at 10:00 and 15:00, and the measurement points are arranged as shown in Figure 8 and Figure 9.
2.2.2 Analysis of survey data It can be seen from the survey data processing that the illumination of the west office is higher than that of the afternoon, while the illumination of the eastward room is significantly higher than that of the afternoon, but the attenuation law is consistent. The position data attenuation of the center line of the window is very large, and it decays rapidly from the window. At about 1.5m from the window, the ratio to the outdoor illumination is attenuated to only 1/5 or even lower at the window (see Figure 10). .
2.3 South-facing window glare problem <br> During the investigation, we found that the south-facing room window generally has the problems of excessive illumination and window glare. Basically, the inner sunshade is needed to make the room reach a comfortable light environment, otherwise it is very It is easy to produce local glare. Therefore, in the investigation process, we also conducted a subjective questionnaire survey on the glare problem of the office environment. The results of the questionnaire show that in addition to a certain degree of glare in the south, there are certain bright spots or dazzling light in the northward room. This phenomenon is very common in office buildings and requires a part of the transformation. The survey used questionnaires and on-site questions and answers to investigate the satisfaction of office workers with the light environment in the office. The content includes a feeling of lightness and darkness, and a feeling of discomfort or glare. The results of the questionnaire (Figure 11) show that in the survey of the overall perception of the indoor light environment, the number of people who think that the overall light environment is moderate is only 36%, and the satisfaction is not high. Secondly, the overall environment is slightly dim and slightly dazzling. The total number is 55%, and the number of people who think that they are slightly dim is slightly more than the number of people who think it is slightly dazzling. In the investigation of the glare problem in the office light environment, the number of people who think that there is glare in the office accounted for 17%. Among them, in the survey of the south office, the number of people who believed that there was glare accounted for 28%, which was significantly higher than the north. The number of people who believe that glare is present in the office survey is only 6%.
2.4 Unreasonable selection and arrangement of lamps <br> In the investigation, in addition to measuring the illumination when turning off the lights, the usage status at the time of normal lighting was also measured. It was found that even with the addition of artificial lighting, the illumination level of the working surface in some places remains the same. Unable to reach the value specified in the specification. Through the investigation, it is possible to grasp the specific room type in which the illuminance of the luminaire is insufficient, and provide a basis for the design of the interior lighting improvement.
2.4.1 Selection of survey data After the addition of artificial lighting, the office where the lighting still fails to meet the requirements is mainly located in the north direction. The experimental data selected the north office of the office building of the School of Mechanical Engineering and the office building of the School of Management. Both samples belong to the typical open office. There are two side windows in the north facing room. The room area is (40-50) m2, and 4 rooms are evenly arranged. Fluorescent tube (T8), the office has 7-8 staff members. The measurement time is 10:00 and 15:00, and the measurement points are arranged as shown in Fig. 12 and Fig. 13.
2.4.2 Analysis of survey data Through data analysis, it can be found that after the artificial illumination is added, the uniformity of illumination is alleviated, but after 2.5m from the window, the illumination value will still decay to below 300lx, the lowest place. Under artificial lighting, it is only about 100lx. The "Architectural Lighting Design Standards" GB50034-2013 specifies the lighting power of office buildings and the corresponding required illuminance values ​​(Table 2). It can be seen that although some offices have artificial lighting attached, they still cannot meet the illuminance values ​​required by the specification, which is very unfavorable for those who work in this environment for a long time. Therefore, efficient lighting fixtures, reasonable lighting layout, etc. have an important role in the improvement of indoor light environment.
Suggestions for Improvement
Suggestions for the lack of daylighting in the north are as follows:
1) The window area on the north side can be appropriately increased or the reflectivity of each surface in the room can be increased, and a larger amount of light can be obtained, and the limited light in the room can be uniformly diffused to improve the brightness of the room;
2) Partially cooperate with effective daytime lighting to provide sufficient and stable light for the room;
3) Use the south façade of the adjacent north side building to set up some reflectors. Adjusting the angle of the reflector allows the light to enter the office from the north side, especially for the lower office in the north. However, this method has a large limitation, and it is necessary to have an office building adjacent to the north side, and a better improvement effect can be achieved only when the floor spacing is appropriate.
Suggestions for the uniformity of illumination in the office space of Dajinshen are as follows:
1) Using the lighting shelf, the lighting inside the room with large depth can be solved to some extent (see Figure 15). In order to increase the uniformity of illumination in the room, there is no exit downwards in a distance close to the window, and the exit of the light is opened inside the room, so that the illumination near the window is not further increased.
2) Using a reflective high window structure (see Figure 16), a set of specular reflection devices are installed at the top of the window. When the sunlight hits the reflective surface, it is reflected once to reach the ceiling inside the room, and is reflected by the diffuse reflection of the ceiling. Inside the room. The high reflection window increases the uniformity of illumination and illumination throughout the room.
Suggestions for window glare are as follows:
1) Reduce the brightness of the window. The brightness of the window can be reduced by using internal and external shading to reduce the influence of uncomfortable glare.
2) The use of reflective high window structure can also reduce the entry of direct sunlight, reduce the effects of direct glare and ground reflection glare, while increasing the background brightness of the entire room and reducing the impact of uncomfortable glare.
Suggestions for office artificial lighting are as follows:
1) Improve the efficiency of the light source. In the office lighting design, double-ended straight tube fluorescent lamps are often used. Added "T8 and T5 high frequency fluorescent lamps" products. Due to the improvement of technology, the light efficiency of the light source product is increased by about 10% to 20% compared with the conventional three primary color light source.
2) Improve the efficiency of the luminaire. The use of new grille luminaires, under the premise of meeting glare, reduces the unnecessary grid area, thus improving the efficiency of the entire luminaire, reaching more than 70%.
3) Reasonably arrange the position of the luminaire. The arrangement direction of the straight tube fluorescent lamp should be parallel to the person's main line of sight, generally perpendicular to the window, which can effectively alleviate the problem of uniformity of illumination.
summary
Through the investigation and study of the light environment of 16 office buildings near Tianjin University, it is found that there are still many problems in the light environment of the office, such as: insufficient amount of light in the north direction, uniformity of lighting in the office, large-direction window glare, and office labor. Lighting fixture efficiency, lighting layout and other issues. In response to the different problems found in the survey, this paper proposes corresponding transformation proposals to provide strong support for creating a good office space indoor light environment.
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