A method for analyzing key influencing factors of building surface irradiance

Abstract

The present invention discloses a method for analyzing key influencing factors of surface irradiance of a building complex, and belongs to the field of surface irradiance. The method comprises: building a building complex model, analyzing and constructing building surface irradiance influencing factors, analyzing building complex surface irradiance influencing factors, and analyzing key influencing factors of building complex surface irradiance. The present invention first analyzes and classifies existing irradiance influencing factors, and constructs new influencing factors based on radiation transfer theory and the influence of building complexes on radiation transfer; secondly, the influencing factors of each radiation component are analyzed, and the combination relationship between each factor and the potential key influencing factors of each radiation component are established; finally, taking the annual average short-wave total irradiance value as an example, the key influencing factors of direct, scattered and reflected components in the surface irradiance of the building complex are screened and established through statistical analysis.

Description

Technical Field

[0001] The invention relates to surface irradiance, and in particular to a method for analyzing key influencing factors of surface irradiance of a building complex. Background Art

[0002] As an important energy source for photovoltaic resource utilization of building complexes, the distribution law of surface irradiance in building complexes is of great significance to the study of photovoltaic resource utilization potential of building complexes. Existing studies mostly use influencing factors based on building complex design parameters (such as volume ratio, building density, etc.) as independent variables when describing the law of surface irradiance of building complexes. However, such building complex design parameters are too macroscopic to achieve a refined description of the law of surface irradiance of local buildings in the building complex. In addition, existing studies mainly use qualitative descriptions when describing the law of influencing factors of surface irradiance of building complexes. The research is also mostly based on numerical analysis of specific cases. Due to the limitation of the building complex design parameters of the case, the generalizability of quantitative conclusions is limited. Finally, the conclusions of existing studies are mostly data analysis and conclusion elaboration, lacking theoretical derivation and analysis of influencing factors based on the theory of building surface radiation transfer. Therefore, it is impossible to theoretically derive the key factors affecting the surface irradiance of building complexes, and then derive the key influencing factors of surface irradiance. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a method for analyzing key influencing factors of surface irradiance of building complexes.

[0004] Technical solution: A method for analyzing key influencing factors of building surface irradiance, including:

[0005] S1. Construct the factors affecting the surface irradiance of the building complex;

[0006] S1.1. Construction of new microscopic influencing factors of building complex surface irradiance: Construction of weighted urban zenith angle WUZA: uniformly locate the azimuth ray beam to the south, and calculate the weighted urban zenith angle of the micro-element surface on the vertical building complex section corresponding to each ray beam; Construction of average incidence factor AIF: calculate the cosine value cosθ of the solar incident angle θ of the micro-element surface and take the average value as the average incidence factor; Construction of weighted urban elevation angle WUHA: uniformly locate the azimuth ray beam to the north, and multiply the azimuth angle of the azimuth ray beam in the horizontal plane by the sine value to construct the weighted urban elevation angle; Construction of environmental reflection factor EAF: take the product of the angular coefficient of the solar reflected radiation of the micro-element surface and the reflectivity of the corresponding wavelength of the reflected radiation as the environmental reflection factor;

[0007] S1.2. Analyze the correlation of influencing factors: The Pearson correlation coefficient r is used to assess the correlation between variables for the surface irradiance influencing factors of the micro-element surface of the building complex. The larger the correlation coefficient, the higher the linear correlation between the influencing factors, and the less suitable it is as the key influencing factor of the surface irradiance of the building complex. On the contrary, the smaller the correlation coefficient, the more suitable it is as the key influencing factor of the surface irradiance of the building complex.

[0008] S2. Analyze the factors affecting the irradiance on the surface of the building complex: The total irradiance value of the micro-element surface is composed of direct solar irradiance, sky diffuse irradiance and reflected irradiance; among them, the potential key influencing factors of direct solar irradiance are the weighted urban zenith angle, the average value of the incidence factor and the average value of the direct solar radiation intensity; the potential key influencing factors of sky diffuse radiation are the sky angle coefficient and direct solar irradiance; the potential key influencing factors of reflected irradiance are the urban elevation angle, the weighted urban zenith angle and the environmental reflection factor;

[0009] S3. Analyze the key factors affecting the surface irradiance of buildings;

[0010] S3.1. Determination of key influencing factors: Use the building complex surface irradiance influencing factors to perform linear fitting on the annual average values ​​of direct solar irradiance, sky diffuse irradiance and reflected irradiance of the building complex micro-element surface, and finally take the single influencing factor with the highest fitting degree as the key influencing factor.

[0011] Preferably, the method for constructing the building complex is: first construct a single building based on the design parameters of the single building, and then replicate the single building several times according to the building spacing and staggered distance; then, based on the building complex modeling parameters and meteorological files, all building design parameters are randomly sampled to model the building complex, and the construction of the building complex model is completed.

[0012] Preferably, in S1, when designing parameters for a single building, the reference characteristic dimension is selected as the building width, and then the remaining dimensions of the building design are designed as multiples of the building width.

[0013] Preferably, the building complex model constructed in S1 includes: 500 training set building complexes and 100 test set building complexes.

[0014] Preferably, in S1.2, the value of the correlation coefficient r is between -1 and +1. If 0≤|r|<0.4, it indicates a low linear correlation between the variables; if 0.4≤|r|<0.7, it indicates a significant linear correlation between the variables; if 0.7≤|r|<1, it indicates a high linear correlation between the variables.

[0015] Preferably, in S1.1, the weighted city zenith angle calculation formula is:

[0016] ,

[0017] Where WUZA is the weighted urban zenith angle, in degrees; z is the microelement zenith angle under the θ azimuth ray beam, in degrees; θ is the angle between the ground projection line of the azimuth ray beam and the due east direction, in degrees;

[0018] In the calculation process of constructing the average incidence factor, cosθ takes the value of 0 when the angle of incidence is negative;

[0019] The calculation formula of weighted city elevation angle is:

[0020] ,

[0021] Where WUHA is the weighted urban elevation angle, in degrees; UHA θ is the elevation angle of the microelement surface city under the azimuth ray beam of θ, in degrees; θ is the angle between the ground projection line of the azimuth ray beam and the due east direction, in degrees;

[0022] The calculation formula of the environmental reflection factor is:

[0023] ,

[0024] Where EAF is the environmental reflection factor, dimensionless; GVF is the ground angle factor, dimensionless; BVF is the building angle factor, dimensionless; ρ g is the ground reflectivity, dimensionless; ρ b is the comprehensive reflectivity of the building complex, dimensionless; where the multiple terms of the reflectivity are based on the consideration of multiple reflections. Further summing up the geometric series, the calculation formula for the environmental reflection factor is:

[0025] .

[0026] Preferably, in S2, the total irradiance value is expressed as follows in the quantitative expression process:

[0027] ,

[0028] Where F dir,i is the direct solar irradiance of microelement surface i; F dif,i is the sky diffuse irradiance of microelement surface i; F ref,i is the reflected irradiance of microelement surface i; F other,i are the other influencing factors of the microelement surface i;

[0029] The potential key influencing factors of direct solar irradiance are expressed as:

[0030] ,

[0031] Chinese style WUZA iis the weighted city zenith angle of micro-surface i, in degrees; AIF i is the average incidence factor of the microelement surface i, dimensionless; DNI mean It is the average value of the direct solar radiation intensity in the meteorological file within the corresponding interval in the meteorological file, in W / m 2 ;

[0032] The potential key influencing factor of diffuse sky radiation is expressed as:

[0033] ;

[0034] ,

[0035] Where: SVF i is the sky angle coefficient of the microelement surface i, dimensionless;

[0036] The potential key influencing factor of reflected irradiance is expressed as:

[0037] ,

[0038] Where UHA i is the elevation angle of the city on microelement surface i, in degrees; EAF i Rad is the environmental reflection factor of microelement surface i, dimensionless; mean It is the average value of the radiation intensity in the corresponding interval in the meteorological file, in W / m 2 ; Rad mean It characterizes the overall intensity of environmental radiation in the micro-element surface, and can take the total irradiance value, direct solar radiation intensity value or sky scattered irradiance value as the characteristic value.

[0039] Preferably, in S3.1, the key factor of the annual average solar direct irradiance value is the solar direct radiation composite factor, that is:

[0040] ,

[0041] Where I dir,i is the direct solar irradiance value of microelement surface i, WUZA i is the weighted city zenith angle of micro-surface i, in degrees, AIF i is the average incidence factor of the microelement surface i, dimensionless, DNI mean It is the average value of the direct solar radiation intensity in the meteorological file within the corresponding interval in the meteorological file, in W / m 2 ;

[0042] The sky view factor (SVF) is a key factor affecting the annual average sky diffuse irradiance value, namely:

[0043] ,

[0044] Where I dif,i is the sky diffuse irradiance value of micro-element surface i, SVF i is the sky angle coefficient of the microelement surface i, dimensionless;

[0045] The global horizontal irradiance (GHI) is the key factor affecting the annual average reflected irradiance, namely:

[0046] ,

[0047] Where I ref,i is the reflected irradiance value of microelement surface i, EAF i is the environmental reflection factor of microelement surface i, dimensionless, UHA i is the elevation angle of the city on microelement surface i, in degrees, GHI mean It is the average value of the total radiation intensity on the horizontal surface in the corresponding interval in the meteorological file, in W / m 2 ;

[0048] The total irradiance of the micro-element surface is the sum of the direct solar irradiance, sky diffuse irradiance and reflected irradiance of the micro-element surface, that is:

[0049] ,

[0050] Where I g,i is the total irradiance value of micro-element surface i; since the direct solar irradiance, sky diffuse irradiance and reflected irradiance of the micro-element surface are not much different in magnitude, the key influencing factors of the three can be used together as the key influencing factors of the total irradiance value, that is:

[0051] .

[0052] Preferably, S3 also includes S3.2, comparison of effectiveness of key influencing factors: using multivariate linear regression to fit the existing sample data of building surface irradiance influencing factors, so as to explore the expression effect of the quantitative expression formula based on the existing building surface irradiance influencing factors on the building surface irradiance; wherein, the existing building complex surface irradiance influencing factors are divided into geographical influencing factors, macro influencing factors and micro influencing factors; geographical influencing factors include season and region; macro influencing factors include building complex layout, orientation, building complex density, building complex floor area ratio and height-to-width ratio; micro influencing factors include sky angle coefficient, floor height ratio, reflectivity and city elevation angle.

[0053] Preferably, S3.2 is specifically: by multiple linear regression analysis, based on x (i) The sample prediction formula is:

[0054] ,

[0055] In the formula, n is the number of attributes of a single sample; θ is the regression coefficient; x (i) is the microelement surface sample of the i-th building complex; θ and x (i) It can be expressed as:

[0056] ;

[0057] ,

[0058] Define the independent variable data set, dependent variable data set, and regression coefficient data set as follows:

[0059] ,

[0060] Where m is the number of samples; n is the number of influencing factors; the independent variable data set X∈ℝ m×(n+1) ; Dependent variable data set Y∈ℝ m×1 ; Regression coefficient data set θ∈ℝ (n+1)×1 ;

[0061] Then the solution of multiple linear regression can be transformed into:

[0062] ,

[0063] After solving, we get:

[0064] ,

[0065] Combined with the existing irradiance influencing factors, the regression coefficient matrix is:

[0066] ,

[0067] After solving the regression model based on the existing influencing factors, the expression formula of the building surface irradiance based on the existing influencing factors is formed; at the same time, based on the three key influencing factors of direct, scattered and reflected mentioned above, the regression coefficient matrix is ​​set as:

[0068] ,

[0069] Compare the solved results.

[0070] Beneficial effects: The present invention first analyzes and classifies the existing irradiance influencing factors, and constructs new influencing factors based on the radiation transfer theory and the influence of building complexes on radiation transfer; secondly, the influencing factors of each radiation component are analyzed, and the combination relationship between each factor and the potential key influencing factors of each radiation component are established; finally, taking the annual average short-wave total irradiance value as an example, the key influencing factors of direct, scattered and reflected components in the surface irradiance of the building complex are screened and established through statistical analysis. The present invention studies the influencing factors of the radiation transfer process and the surface irradiance of buildings in the building complex environment, which can not only derive the key factors affecting the surface irradiance in the building complex environment, but also further use the key influencing factors as optimization indicators to guide the optimization design of future community building complexes, thereby forming a popularizable optimization design method for future community building complexes to guide engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 It is a schematic diagram of building spacing and staggered distance;

[0072] Figure 2 It is a schematic diagram of the layout of some building complex models;

[0073] Figure 3 This is a schematic diagram for calculating the building width-to-height ratio;

[0074] Figure 4 It is a UHA schematic diagram of the micro-element point of a two-dimensional building complex;

[0075] Figure 5 It is a schematic diagram of UHA calculation of micro-element points of three-dimensional building complex;

[0076] Figure 6 It is a south ray diagram of the microelement surface of the three-dimensional building complex;

[0077] Figure 7 It is a schematic diagram of the numerical calculation of the zenith angle;

[0078] Figure 8 This is a weather data chart of radiation on a sunny day;

[0079] Fig. 9 It is a schematic diagram of weighted city zenith angle calculation;

[0080] Fig.10 It is a schematic diagram of the direct solar radiation in the building complex being reflected by the south wall and radiated to the north wall;

[0081] Fig.11 It is a schematic diagram of weighted city elevation angle calculation;

[0082] Fig.12 This is a schematic diagram of the scattered radiation intensity distribution in the sky on a clear day;

[0083] Fig.13It is a schematic diagram of reflected radiation from a building complex;

[0084] Fig.14 It is the correlation calculation result of irradiance influencing factors. DETAILED DESCRIPTION

[0085] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0086] Example

[0087] (1) Construction of building complex model

[0088] Since it involves a large amount of statistical analysis based on building complex design parameters and radiation data, it is necessary to construct a representative future community building complex model and perform irradiance simulation. The public buildings in the future community not only have a low number of floors, but are also mostly single-building groups, so the modeling scope is mainly residential and commercial buildings. In terms of the design parameters of single buildings, the benchmark characteristic dimension is selected as the building width (the size of the building in the north-south direction), and the remaining dimensions are designed as multiples of the building width. In terms of building complex modeling, first construct a single building based on the design parameters of the single building, and then replicate the single building according to the building spacing and staggered distance. The total number of buildings is 9. In this embodiment, the north-south spacing of the building complex is equal to the east-west spacing, and there is a certain staggered distance between the second row of buildings and the remaining buildings to enrich the layout of the building complex. The building spacing and staggered distance are shown in the figure. Figure 1 , where the staggered distance is a specific multiple of the building length (the size of the building in the east-west direction) during modeling. The layout parameters of the building complex are shown in Table 1.

[0089] Table 1 Design parameters of building complex

[0090] Design parameters Value Building Height 1，2，3，4，5 Building Length 1，4 / 3，5 / 3，2，7 / 3，8 / 3，3 Building spacing 1 / 3，2 / 3，4 / 3，7 / 3，11 / 3，16 / 3 Building staggered distance -1，-2 / 3，-1 / 3，0，1 / 3，2 / 3，1 Comprehensive reflectivity of building complex 0.1，0.2，0.3，0.4，0.5，0.6 Ground reflectivity 0.1，0.2，0.3

[0091] Note: When calculating the staggered distance, the characteristic value is the length of the building rather than the width.

[0092] The research conclusions of the key influencing factor analysis of the present invention should be oriented towards the construction of communities across the country. Therefore, in terms of importing meteorological files, the climate zoning and the enumeration of typical cities in the "Energy-Saving Design Standard for Public Buildings" GB50189-2015 are referred to, and major cities in different climate zones are selected, see Table 2.

[0093] Table 2 List of selected cities in different climate zones

[0094] Climate zones Select City Severely cold zone A Karamay, Harbin, Mohe, Mudanjiang, Nenjiang, Huma Severe cold zone B Yinchuan, Hami, Hohhot, Changchun, Shenyang, Urumqi, Jiuquan Cold Regions Taiyuan, Lanzhou, Lhasa, Beijing, Xi'an, Zhengzhou Hot summer and cold winter areas Nanjing, Shanghai, Hangzhou, Wuhan, Changsha, Chongqing, Chengdu Hot summer and warm winter areas Fuzhou, Xiamen, Haikou, Wuzhou, Nanning Temperate areas Kunming, Guiyang, Tengchong, Lijiang, Lancang, Simao, Lincang

[0095] According to the above building complex modeling parameters and meteorological file library, this embodiment adopts random sampling method to model building complexes for all parameters, and constructs a total of 500 training set building complexes and 100 test set building complexes in 38 cities across the country (the building complexes generated by copying individual buildings are of equal height. Considering that the individual buildings in the actual building complex are not of equal height, this study randomly modifies the building heights in 50% of the samples according to Table 1. The schematic diagram of the layout of some building complex models is shown in Figure 2 ). After the simulation is completed, the relevant parameters are sampled using the discrete building complex micro-element surface as the sample unit.

[0096] (2) Analysis and construction of factors affecting building surface irradiance

[0097] (21) Analysis of factors affecting existing surface irradiance

[0098] Existing research generally studies the irradiance distribution law of building complexes from aspects such as building layout, season, orientation, region, building density, building complex volume ratio, aspect ratio, sky angle coefficient, urban elevation angle, floor height ratio, and reflectivity. The following will analyze each influencing factor one by one.

[0099] Building complex layout: Building complex layout reflects the spatial geometric relationship between buildings. Typical building complex layout forms include enclosed building complex, dot-matrix building complex, and strip-shaped building complex. The remaining building complex layout forms can theoretically be achieved through the combination of these three basic layouts. Enclosed building complexes will weaken the irradiance in the enclosed space through the building shielding effect, while dot-matrix building complexes and strip-shaped building complexes make more full use of solar energy. Building complex layout is suitable for describing the overall information of the building complex, and this influencing factor is difficult to quantify. Therefore, when the irradiance on the building surface is quantitatively expressed, the building complex layout should not be used as a key influencing factor (independent variable).

[0100] Season: Season mainly affects the irradiance distribution in the building complex through three factors: radiation intensity, sunshine duration and solar incident angle. In terms of radiation intensity, the total irradiance, direct solar radiation and sky scattered radiation are all higher in summer than in winter, so the overall radiation intensity is higher in winter; in terms of sunshine duration, the sunshine duration in summer is longer than in winter, so the overall cumulative radiation in summer is higher than in winter; in terms of solar incident angle, the solar altitude angle is higher in summer, so the incident angle is larger than in winter. In theory, the larger the incident angle at the same radiation intensity, the smaller the radiation heat, but due to the small radiation intensity and sunshine duration in winter, the overall radiation intensity is lower than in summer.

[0101] Orientation: Orientation also mainly affects the irradiance of the building surface through three factors: radiation intensity, sunshine duration, and solar incident angle. Generally speaking, the solar radiation intensity at noon is higher than that in the afternoon, and higher than that in the morning. Therefore, for buildings in the northern hemisphere, the solar radiation intensity received by the facade is south wall> west wall> east wall> north wall; in terms of sunshine duration, it can be known from basic astronomical theory that the sunshine duration of buildings in the northern hemisphere facing south is higher than that facing east and west, while the sunshine duration facing north is the shortest; in terms of solar incident angle, since the solar altitude angle is the largest at noon, the incident angle facing east and west is smaller than that of the south wall. In summary, the irradiance of the south wall is the highest, followed by the west wall and the east wall, and the north wall is the lowest.

[0102] Region: The impact of region on building surface irradiance is mainly achieved through meteorological conditions and geographical location. Meteorological conditions are mainly reflected in the radiation intensity, while geographical location affects the calculation of the sun's position through longitude and latitude, and then affects the sunshine duration and solar incidence angle together with the building complex. Generally speaking, the irradiance of building surfaces in low-latitude regions close to the equator is higher than that in high-latitude regions.

[0103] Building density: Building density reflects the ratio of the floor area of ​​the building complex to the total land area. Under the same building height and floor area, the higher the building density, the smaller the distance between buildings, indicating that the sun needs a larger incident angle to cover the direct solar radiation to the bottom of the building. Therefore, building density can indirectly reflect the strength of the shielding effect of the building complex on direct solar radiation and scattered radiation from the sky. At the same time, high-density buildings also increase the ratio of reflected radiation inside the building complex to total radiation.

[0104] Building complex volume ratio: The volume ratio reflects the ratio of the total building area of ​​the building complex to the total land area. Similar to building density, the higher the volume ratio, the higher the proportion of the building in the unit space, that is, the building complex has an enhanced shielding effect on direct solar radiation and sky scattered radiation. At the same time, a high volume ratio also corresponds to a high proportion of reflected radiation.

[0105] Aspect ratio: The aspect ratio is derived from the 2D street valley model ( Figure 3 ), which is numerically equal to the ratio of building height to street valley width (building spacing). In the calculation of the height-to-width ratio of three-dimensional building complexes, the average value of the ratio of building height to building spacing is generally taken. The higher the height-to-width ratio, the more obvious the shielding effect of the building complex on direct solar radiation, which means a reduction in the sunshine duration of the building facade under the same meteorological conditions. At the same time, the higher the height-to-width ratio, the smaller the sky angle of the building facade and the larger the building and ground angle, which means lower sky scattered radiation and a higher proportion of reflected radiation.

[0106] Floor height ratio: The floor height ratio is the percentage of the control point height to the building height, reflecting the relative height of the micro-element surface on the building facade. The larger the floor height ratio, the weaker the shielding effect of the building complex on the micro-element surface, the longer the sunshine duration and the sky scattered radiation will increase, and the proportion of reflected radiation will decrease.

[0107] Sky angle coefficient: The sky angle coefficient reflects the openness of the sky angle of the micro-element surface on the building facade. The larger the sky angle coefficient, the larger the sky angle, and the smaller the probability of direct solar radiation being blocked. At the same time, the larger the sky angle, the stronger the sky scattered radiation and the weaker the reflected radiation. Existing studies have shown that for relatively complex urban building complex forms, the sky angle coefficient is a good descriptive parameter.

[0108] City elevation angle: The city elevation angle reflects the visual angle of the building within the micro-element field of view. For the two-dimensional street valley model, the formula for calculating the city elevation angle is:

[0109] (1)

[0110] Where H is the relative height of the building; W is the distance between buildings; UHA θ is the city elevation angle under a specific azimuth ray beam.

[0111] Figure 4 A schematic diagram of the city elevation angle is given, from which it can be seen that the sum of the city elevation angle and the zenith angle is 90°. For a three-dimensional building complex, given several azimuth ray beams and along the vertical direction, the street valley section corresponding to each ray beam is obtained ( Figure 5 (Figure 2 is a schematic diagram of the calculation of the city elevation angle under 7 azimuth ray beams), then the city elevation angle is the average of the elevation angles under the vertical sections corresponding to each ray beam. From the calculation formula, it can be seen that the concept of the city elevation angle is similar to the building aspect ratio, which is actually the specific implementation of the transformation of the aspect ratio from two-dimensional to three-dimensional building complexes. The larger the city elevation angle, the higher the average building aspect ratio, the more obvious the shielding effect of the building complex, the shorter the sunshine duration and the weaker the sky scattered radiation. Although the city elevation angle reflects the potential of the building shielding effect and the sunshine duration of the building facade, it can be seen from the direct solar radiation calculation formula 2 that the direct solar irradiance is also related to the solar incident angle and the direct solar radiation intensity. Therefore, the city elevation angle has certain limitations in reflecting the direct solar irradiance of the building complex.

[0112] (2)

[0113] Where I dir,i is the direct solar irradiance value of the microelement surface, W / m 2 ;Flag i Boolean value for sun visibility, Flag i =1 means that the microelement surface i is not blocked; I dir0 is the direct solar radiation intensity, W / m 2 ; θ is the solar incidence angle, °.

[0114] Reflectivity: Reflectivity reflects the ratio of the reflected wave power of the micro-element surface to the incident wave power under radiation of a specific wavelength. According to the reflected radiation calculation formula, the reflected irradiance received by the micro-element surface is not strongly correlated with the reflectivity of the micro-element surface itself, but is strongly correlated with the reflectivity of the surrounding buildings and the ground. Therefore, only when the overall environmental optical properties tend to be consistent, can the reflectivity be used as an influencing factor related to the reflected irradiance of the micro-element surface.

[0115] Based on the analysis of the above influencing factors, the factors affecting the irradiance of the building surface can be divided into three types. The first type has nothing to do with the building complex itself, but is related to the area and environment where the building complex is located. This study calls it geographical influencing factors, including seasons, regions, etc. The remaining influencing factors can be further divided into macro influencing factors and micro influencing factors according to whether they can describe the physical information of the local micro-element surface of the building complex. Macro influencing factors include building complex layout, orientation, building density, building complex volume ratio, height-to-width ratio, etc. Micro influencing factors include sky angle coefficient, floor height ratio, reflectivity, urban elevation angle, etc. Among them, the macro influencing factors reflect the overall information of the building complex and are suitable for describing the overall information of the building complex. When it comes to the radiation information of the local area of ​​the building complex, the macro influencing factors cannot meet the corresponding accuracy requirements. In addition, according to the analysis of radiation transfer theory, most macro influencing factors are not directly related to direct solar radiation, sky scattered radiation and reflected radiation, but indirectly affect the irradiance of the building surface through intermediate influencing factors (such as sunshine duration, solar incident angle, radiation intensity, etc.). Therefore, macro influencing factors are not suitable as key influencing factors for describing the law of building surface irradiance.

[0116] In terms of micro-influencing factors, the number of existing micro-influencing factors is far less than that of macro-influencing factors. Among them, the sky angle coefficient and the city elevation angle express the potential of the building facade to receive irradiance to a certain extent, while the floor height ratio, as an indirect variable, is not suitable as a key influencing factor of irradiance. As for reflectivity, the reflectivity of the micro-element surface is not directly related to the reflected radiation received by the micro-element surface. In summary, in order to study the key influencing factors of the surface irradiance of the building complex, it is necessary to summarize and refine the existing influencing factors, derive the directly related variables that affect the surface irradiance of the building complex, and further construct new micro-influencing factors to make up for the limitations of the existing influencing factors in expressing the irradiance of the building surface.

[0117] (22) Construction of new microscopic influencing factors of surface irradiance

[0118] From the above, we can see that most geographical influencing factors and macro-influencing factors indirectly affect the irradiance of the building complex surface through intermediate influencing factors (such as sunshine duration, solar incident angle, radiation intensity, etc.), and they can only describe the overall information of the building complex and the environment, and cannot specifically describe the physical information of a specific micro-element surface. Therefore, the new influencing factors should start from the micro-scale and reflect the direct influencing factors of irradiance in the building complex environment such as sunshine duration, solar incident angle, and radiation intensity on the micro-element surface.

[0119] (221) Weighted Urban Zenith Angle (WUZA)

[0120] From Formula 2, we can see that one of the key items in the calculation formula for direct solar radiation is the product of the direct solar radiation intensity and the visual judgment Boolean value: Flag i I dir0 , in terms of its cumulative value, it is directly related to the sunshine duration and the intensity of direct solar radiation. For macro-influencing factors, although parameters such as building density and volume ratio have a certain correlation with the sunshine duration of the micro-element surface, they cannot describe the micro-element surface at the micro level; for micro-influencing factors, considering that the sun is mainly in the south sky direction in the northern hemisphere, and the existing influencing factors cannot reflect this fact, there are certain limitations in characterizing the sunshine duration. This study is based on the UHA parameter calculation concept and uniformly defines the azimuth ray beam as the south direction (such as Figure 6 ), and calculate the zenith angle of the microelement surface on the vertical building complex section corresponding to each ray beam, see Figure 7 .

[0121] Since the cumulative value of direct solar radiation in the time dimension is directly related to the sunshine duration and direct solar radiation, the average urban zenith angle only reflects the information related to the sunshine duration of the micro-element surface, so it is also necessary to add the information related to direct solar radiation. Figure 8 ) It can be seen that the temporal distribution of direct solar radiation under sunny conditions is similar to the sine function. Therefore, the product of the zenith angle and the sine function is integrated over the azimuth angle, and the resulting parameter can reflect the strength of the cumulative value of direct solar radiation.

[0122] The calculation formula of weighted urban zenith angle (WUZA) is defined as follows:

[0123] (3)

[0124] Where WUZA is the weighted urban zenith angle, °; z is the microelement surface zenith angle under the θ azimuth ray beam, °; θ is the angle between the ground projection line of the azimuth ray beam and the due east direction, °.

[0125] Since the south azimuth angle spans 180°, the upper and lower limits of the integral are set to 0 and π respectively. The weighted city zenith angle calculation is shown in the figure. Fig. 9In summary, the weighted urban zenith angle (WUZA) reflects the direct solar radiation receiving potential of the micro-element surface by combining the sunshine duration factor and the direct solar radiation intensity factor.

[0126] (222) Average incidence factor (AIF)

[0127] From the direct solar radiation calculation formula 2, we can know that the direct solar irradiance is also highly related to the solar incident angle. The weighted urban zenith angle reflects the Flag i I dir0 The strength of the term, and the impact of the incident angle on the irradiance can also construct an additional independent factor. In this embodiment, the cosine value cosθ of the solar incident angle θ of the micro-element surface is calculated and the average value is taken as the average incidence factor (AIF). During the calculation process, cosθ takes a value of 0 when the incident angle is negative.

[0128] (223) Weighted Urban Elevation Angle (WUHA)

[0129] Among the existing influencing factors, there are few factors that reflect the reflected irradiance of the building surface, so it is necessary to analyze the factors affecting reflected radiation. According to the theory of geometric optics, direct solar radiation from the south can transfer a large amount of reflected radiation to the north-facing building facade through the south-facing building facade ( Fig.10 ). For north-facing building facades, the more south-facing building facades there are within the field of view, the more visible the sun image is, that is, the greater the elevation angle to the north, the more reflected radiation is received from the south wall.

[0130] From the weighted city zenith angle correlation analysis, it can be seen that the angle multiplied by the radiation intensity at the corresponding azimuth is more suitable for reflecting the overall radiation strength. Therefore, the weighted city elevation angle uniformly defines the azimuth ray beam as the north direction, and multiplies the elevation angle at a specific azimuth by the sine value to reflect the intensity of reflected radiation received from the solar image. The calculation formula is:

[0131] (4)

[0132] Where WUHA is the weighted urban elevation angle; UHA θ is the elevation angle of the microelement surface city under the azimuth ray beam of θ; θ is the angle between the ground projection line of the azimuth ray beam and the east direction.

[0133] Since the north azimuth span is 180°, the upper and lower limits of the integral are set to 0 and π respectively. The weighted city elevation angle calculation is shown in the figure. Fig.11 In summary, the weighted urban elevation angle (WUHA) reflects the potential of the micro-element surface to receive reflected radiation from the south wall by combining the sunshine duration factor and the direct radiation intensity factor of the solar image.

[0134] (224) Environmental reflectance factor (EAF)

[0135] The weighted urban elevation angle reflects the potential of the micro-element surface to receive reflected radiation through the reflection effect of the south-facing building facade on the direct solar radiation. However, the reflected radiation in the building complex will continue to be reflected multiple times after one reflection and redistribute the reflected radiation energy. From the above reflected radiation calculation formula, it can be seen that the calculation formula for plane reflected irradiance is:

[0136] (5)

[0137] Where E is the unit matrix; F ij is the angular coefficient matrix; ρ N×N λ is the reflectivity matrix corresponding to the wavelength; I R λ is the effective radiation value matrix projected outward from the plane. R λ Generally, it is related to meteorological parameters. In weather conditions with high radiation intensity, reflected radiation is relatively strong. The remaining two parameters are the angular coefficient and the reflectivity, and the two are in a multiplication relationship. Therefore, in this embodiment, the environmental reflection factor (EAF) is constructed as the product of the angular coefficient and the reflectivity. At the same time, considering the multiple reflection effect, the calculation formula of the environmental reflection factor is:

[0138] (6)

[0139] Where EAF is the environmental reflection factor, dimensionless; GVF is the ground angle factor, dimensionless; BVF is the building angle factor, dimensionless; ρ g is the ground reflectivity, dimensionless; ρ b is the comprehensive reflectivity of the building complex, dimensionless; where the multiple terms of the reflectivity are based on the consideration of multiple reflections. Further summing up the geometric series, the calculation formula for the environmental reflection factor is:

[0140] (7).

[0141] (23) Correlation analysis of impact factors

[0142] In order to study the influencing factors of irradiance and further screen the key influencing factors, this embodiment first performs a correlation analysis on the existing influencing factors and the new influencing factors. According to the building complex modeling information in Table 1, this study analyzes 2345205 samples of 500 buildings, each sample is a single micro-element surface, and a total of 19 attributes are: sky angle factor (SVF), building angle factor (BVF), ground angle factor (GVF), building density (BD), building complex volume ratio (PR), building complex aspect ratio (AR), floor height (FHR), urban elevation angle (UHA), weighted urban zenith angle (WUZA), weighted urban elevation angle (WUHA), environmental reflection factor (EAF), building complex comprehensive reflectivity (AB), ground reflectivity (AG), latitude (LAT), longitude (LON), average incidence factor (AIF), annual average ground total irradiance value (GHI), annual average direct solar radiation intensity value (DNI), and annual average ground sky diffuse irradiance value (DHI).

[0143] The Pearson correlation coefficient is used to examine the correlation between variables, and its calculation formula is:

[0144] (8)

[0145] The value of the correlation coefficient r is between -1 and +1. If 0≤|r|<0.4, it indicates a low linear correlation between the variables; if 0.4≤|r|<0.7, it indicates a significant linear correlation between the variables; if 0.7≤|r|<1, it indicates a high linear correlation between the variables.

[0146] Depend on Fig.14 The correlation calculation results of irradiance influencing factors show that the traditional macro-influencing factors are highly correlated with each other, among which the correlation coefficients between building density, building volume ratio and height-to-width ratio are all greater than 0.9, indicating high correlation, while the sky angle coefficient, building angle coefficient and ground angle coefficient are negatively correlated. As for the urban elevation angle, its correlation coefficient with the building angle coefficient is 0.91, and its correlation with the environmental reflection factor is 0.73, and its correlation with other factors is relatively low.

[0147] For the four newly constructed influencing factors, the correlation coefficient between the environmental reflection factor and the weighted urban zenith angle is -0.54, indicating that the larger the environmental reflection factor, the larger the non-sky viewing angle of the micro-element surface, and therefore the weighted zenith angle is relatively small. At the same time, the correlation coefficient between the environmental reflection factor and the weighted urban elevation angle is 0.54, indicating that the larger the environmental reflection factor, the larger the weighted urban elevation angle. In addition, the correlation coefficients between the newly constructed influencing factors are all less than 0.2, showing a low linear correlation, indicating that the newly constructed influencing factors are highly independent of each other, and therefore more suitable as key influencing factors of building surface irradiance.

[0148] (3) Analysis of factors affecting the irradiance on the surface of building complexes

[0149] As far as shortwave radiation is concerned, the total irradiance value of the microelement surface is composed of direct solar irradiance, sky diffuse irradiance and reflected irradiance. Therefore, in the quantitative expression process, the total irradiance value can be expressed as:

[0150] (9)

[0151] Where F dir,i is the influencing factor of direct solar irradiance on micro-element surface i; F dif,i is the sky diffuse irradiance influencing factor of micro-element surface i; F ref,i is the factor affecting the reflected irradiance of micro-element surface i; F other,i are the other influencing factors of the microelement surface i. (The influencing factors are a collection of several influencing factors)

[0152] Based on the existing impact factors and the new impact factors constructed in this embodiment, the following will analyze the direct solar radiation, sky scattered radiation and reflected radiation based on the radiation transfer theory, explore the relationship between each impact factor and the irradiance component in the physical process of radiation transfer, and then derive the potential key impact factors of irradiance, paving the way for further establishing key impact factors. In addition, for the convenience of engineering application, this section uses the basic four operations of addition, subtraction, multiplication and division by default when performing combined operations on impact factors.

[0153] (31) Analysis of factors affecting direct solar radiation

[0154] According to the solar direct radiation calculation formula 10, the plane solar direct irradiance is related to Flag i I dir0 The product of the term and cosθ is positively correlated, where the weighted city zenith angle reflects the Flag i I dir0 The strength of the term, while the average incidence factor reflects the size of the cosθ term.

[0155] (10)

[0156] Therefore, the potential key influencing factors of direct solar irradiance can be combined into the product of weighted urban zenith angle, average incidence factor and average direct solar radiation intensity:

[0157] (11)

[0158] Chinese style WUZA i is the weighted urban zenith angle of micro-surface i; AIF i is the average incidence factor of the microelement surface i, dimensionless; DNI meanis the average value of direct solar radiation intensity in the corresponding interval in the meteorological file, W / m 2 .

[0159] (32) Analysis of factors affecting sky scattered radiation

[0160] One of the key potential influencers of diffuse sky radiation is the sky view factor, which is:

[0161] (12)

[0162] Where: SVF i is the sky angle coefficient of the infinitesimal surface i, dimensionless.

[0163] In addition, according to the anisotropic sky scattered radiation intensity distribution theory, the scattered radiation in the circumsolar region accounts for a relatively high proportion of the total sky scattered radiation (see Fig.12 ), and the circumsolar diffuse radiation can be approximately equivalent to the direct radiation from the sun, so the potential key influencing factor of direct solar radiation should also be included in the potential key influencing factor of sky diffuse radiation as the influencing factor of circumsolar diffuse radiation, that is:

[0164] (13).

[0165] (33) Analysis of factors affecting reflected radiation

[0166] Based on equations 5 and 7, the reflected irradiance of the microelement surface is positively correlated with the environmental reflection factor and the effective radiation intensity projected outward from other planes:

[0167] (14)

[0168] Where I ref,i is the plane reflected irradiance of microelement surface i, W / m 2 ; EAF i is the environmental reflection factor of microelement surface i, dimensionless; I R,i Reflects the overall ambient radiation intensity within the visible range of micro-element surface i, W / m 2 .

[0169] by Fig.13 Taking the north wall as an example, the smaller the city elevation angle, the larger the sky viewing angle, indicating that the radiation energy enters the building complex through a larger opening and then reaches the micro-element surface through multiple reflections. Therefore, the overall environmental radiation intensity I R,i It should be negatively correlated with the city elevation angle and positively correlated with the radiation intensity. In addition, since the reflected radiation from the south-facing wall is also an important component of the micro-element surface plane reflected irradiance, I R,i It should be positively correlated with the weighted urban elevation angle and radiation intensity.

[0170] In summary, the factors affecting reflected radiation are:

[0171] (15)

[0172] (16)

[0173] Where UHA i is the city elevation angle of microelement surface i; EAF i Rad is the environmental reflection factor of microelement surface i, dimensionless; mean is the average value of the radiation intensity in the corresponding interval in the meteorological file, W / m 2 ; Rad mean It characterizes the overall intensity of environmental radiation in the micro-element surface, and can take the total irradiance value, direct solar radiation intensity value or sky scattered irradiance value as the characteristic value.

[0174] (4) Analysis of key influencing factors of building surface irradiance

[0175] Existing studies mainly use qualitative descriptions and case descriptions to describe the distribution law of irradiance on the surface of building complexes, which not only lacks extensiveness and universality in conclusions, but also lacks a more complete quantitative expression method. This embodiment aims to determine the key influencing factors of the surface irradiance of building complexes through statistical analysis, so as to be used for the photovoltaic optimization design of future community building complexes.

[0176] Combined with the above research content, the influencing factors included in the statistical analysis are: sky angle factor (SVF), building angle factor (BVF), ground angle factor (GVF), building density (BD), building group volume ratio (PR), building group aspect ratio (AR), floor height (FHR), urban elevation angle (UHA), weighted urban zenith angle (WUZA), weighted urban elevation angle (WUHA), environmental reflection factor (EAF), building group comprehensive reflectivity (AB), latitude (LAT), longitude (LON), average incidence factor (AIF), average level ground total irradiance value (GHI), average direct solar radiation intensity value (DNI), average level ground sky diffuse irradiance value (DHI). In addition, another 7 composite factors are also taken into consideration: WUZA AIF DNI, EAF (90 - UHA) GHI, EAF (90 - UHA)DNI, EAF (90 - UHA) DHI, EAF WUHA GHI, EAF WUHA DNI, EAF WUHA DHI. A total of 25 influencing factors are shown in Table 4. Among them, X13, X14, X16, X17, and X18 are the geographical and weather attributes of the city where the building complex is located, which are taken from the meteorological file (CSWD format) downloaded from the EnergyPlus official website. Since the evaluation of building photovoltaic systems generally uses years as the time unit, the following will take the annual average radiation physical quantity as an example to analyze the key influencing factors of the annual average direct solar radiation, the annual average sky diffuse radiation, and the annual average reflected radiation.

[0177] (41) Determination of key impact factors

[0178] According to linear regression theory, if the model fit R 2 The higher the value, the more significant the influence of the corresponding independent variable on the model. This study uses the 25 variables in Table 4 to perform linear fitting on the annual average direct solar irradiance value, annual average sky diffuse irradiance value and annual average reflected irradiance value of the building complex micro-element surface. The fitting degree R 2 See Table 5. Finally, this study selected the single influencing factor with the highest fit as the key influencing factor of the dependent variable.

[0179] Table 4 List of factors affecting irradiance

[0180] Impact Factor symbol Chinese instructions X1 SVF Sky view factor X2 BVF Building angle coefficient X3 GVF Ground angle factor X4 BD Building density X5 PR Building complex volume ratio X6 AR Aspect Ratio X7 FHR CEILING HEIGHT X8 UHA City elevation X9 WUZA Weighted city zenith angle X10 WUHA Weighted city elevation X11 EAF Environmental reflectivity factor X12 AB Comprehensive reflectivity of building complex X13 LAT latitude X14 LON longitude X15 AIF Average incidence factor X16 GHI Total irradiance on horizontal surface X17 DNI Direct solar radiation intensity X18 DHI Horizontal sky diffuse irradiance X19 WUZA AIF DNI Solar direct radiation composite factor X20 EAF (90 - UHA) GHI Reflected radiation recombination factor X21 EAF (90 - UHA) DNI Reflected radiation recombination factor X22 EAF (90 - UHA) DHI Reflected radiation recombination factor X23 EAF WUHA GHI Reflected radiation recombination factor X24 EAF WUHA DNI Reflected radiation recombination factor X25 EAF WUHA DHI Reflected radiation recombination factor

[0181] Table 5 The fit R between each influencing factor and the dependent variable 2

[0182] Impact Factor Direct solar irradiance value Sky diffuse irradiance value Reflected irradiance value X1 0.53 0.84 0.39 X2 0.20 0.39 0.15 X3 0.25 0.33 0.25 X4 0.06 0.08 0.00 X5 0.05 0.07 0.00 X6 0.04 0.05 0.00 X7 0.31 0.45 0.21 X8 0.12 0.25 0.07 X9 0.60 0.55 0.16 X10 0.07 0.32 0.26 X11 0.28 0.48 0.45 X12 0.00 0.00 0.13 X13 0.05 0.02 0.00 X14 0.02 0.00 0.00 X15 0.04 0.11 0.03 X16 0.16 0.03 0.03 X17 0.22 0.00 0.02 X18 0.04 0.05 0.00 X19 0.92 0.43 0.08 X20 0.20 0.37 0.78 X21 0.12 0.35 0.72 X22 0.28 0.35 0.66 X23 0.13 0.36 0.27 X24 0.10 0.33 0.26 X25 0.16 0.36 0.23

[0183] It can be seen from Table 5 that for the annual average solar direct irradiance value, the solar direct radiation composite factor (X19) is the key factor, namely:

[0184] (17)

[0185] The independent variable is the product of the weighted urban zenith angle (WUZA), the average incidence factor (AIF) and the average annual direct solar radiation intensity (DNI) in the meteorological file. The fitting degree of the independent variable with the model is as high as 0.92. The other influencing factors with higher fitting degrees are the weighted urban zenith angle (R 2 =0.6) and the sky angle factor (R 2 =0.53).

[0186] For the annual average sky diffuse irradiance value, the sky view factor (SVF) is the key influencing factor, namely:

[0187] (18)

[0188] Its fit with the model is 0.84. Other factors with higher fit are weighted city zenith angle (R 2 =0.55), environmental reflection factor (R 2 =0.48) and floor height (R 2 =0.45).

[0189] For the annual average reflected irradiance value, the fitting degree of reflected radiation composite factors X20, X21, and X22 are all higher than 65%. It can be seen from Table 3.4 that X20, X21, and X22 are obtained by multiplying the EAF (90 - UHA) term by different environmental radiation intensity parameters. From the statistical results, it can be seen that the total horizontal irradiance value (GHI) in the meteorological file is most suitable as the characteristic value of the overall radiation intensity of the environment where the micro-element surface is located, that is:

[0190] (19)

[0191] When the eigenvalue is GHI, the corresponding X20 has a fitting degree of 0.78 with the model. In addition, the statistical results show that the micro-element surface reflected irradiance value also has a certain correlation with the environmental reflection factor (X11) (R 2 =0.45).

[0192] From the total irradiance calculation formula, we can know that the total irradiance of the micro-element surface is the sum of the direct solar irradiance, sky diffuse irradiance and reflected irradiance of the micro-element surface:

[0193] (20)

[0194] Since the direct solar irradiance, sky diffuse irradiance and reflected irradiance of the micro-element surface are not much different in magnitude (the ratio of the annual average is 1:1.23:0.36), the key influencing factors of the three can be jointly used as the key influencing factors of the total irradiance value:

[0195] (twenty one)

[0196] (42) Comparison of effectiveness of key impact factors

[0197] From the above analysis, it can be seen that the existing factors affecting the irradiance of building surfaces can be divided into geographical factors, macro factors and micro factors. Most of the geographical factors and macro factors are not directly related to the irradiance, but indirectly affect the irradiance of the building surface through intermediate factors (such as sunshine duration, solar incidence angle, radiation intensity, etc.); secondly, the macro factors are mostly descriptions of the overall information of the building complex, and it is impossible to locate the local area of ​​the building complex through the macro factors to achieve a refined description of the radiation of the local area; thirdly, some macro factors (such as the layout of the building complex) and geographical factors (such as seasons) are difficult to quantify, so they cannot be applied to quantitative analysis; finally, the number of existing micro factors is small, and the regression analysis based on them is also to be studied. The above factors will affect the quantitative expression of building surface irradiance based on the existing factors to a certain extent.

[0198] In order to explore the effectiveness and accuracy of the existing influencing factors in expressing the irradiance on the building surface, this embodiment lists the existing influencing factors that can be quantified (see Table 6), and uses multivariate linear regression to fit the sample data to explore the expression effect of the quantitative expression formula based on the existing influencing factors on the irradiance on the building surface.

[0199] Table 6 List of existing irradiance influencing factors

[0200] Impact Factor symbol Chinese instructions X1 SVF Sky view factor X2 BVF Building angle coefficient X3 GVF Ground angle factor X4 BD Building density X5 PR Building complex volume ratio X6 AR Aspect Ratio X7 FHR CEILING HEIGHT X8 UHA City elevation X12 AB Comprehensive reflectivity of building complex X13 LAT latitude X14 LON longitude X16 GHI Total irradiance on horizontal surface X17 DNI Direct solar radiation intensity X18 DHI Horizontal sky diffuse irradiance

[0201] Based on the basic theory of multiple linear regression, (i) The sample prediction formula is:

[0202] ,

[0203] In the formula, n is the number of attributes of a single sample; θ is the regression coefficient; x (i) is the microelement surface sample of the i-th building complex; θ and x (i) It can be expressed as:

[0204] ;

[0205] ,

[0206] Define the independent variable data set, dependent variable data set, and regression coefficient data set as follows:

[0207] ,

[0208] Where m is the number of samples; n is the number of influencing factors; the independent variable data set X∈ℝ m×(n+1) ; Dependent variable data set Y∈ℝ m×1 ; Regression coefficient data set θ∈ℝ (n+1)×1 ;

[0209] Then the solution of multiple linear regression can be transformed into:

[0210] ,

[0211] After solving, we get:

[0212] ,

[0213] Combined with the existing irradiance influencing factors in Table 6, let the regression coefficient matrix be:

[0214] ,

[0215] After solving the regression model based on the existing influencing factors, the expression formula of the building surface irradiance based on the existing influencing factors is formed; at the same time, based on the three key influencing factors of direct, scattered and reflected mentioned above, the regression coefficient matrix is ​​set as:

[0216] ,

[0217] The results after solution are compared and shown in Table 7.

[0218] Table 7 Comparison of the accuracy of expression formulas based on existing impact factors and key impact factors

[0219] <![CDATA[Training set R 2 > <![CDATA[Test set R 2 > Training set RMSE (%) Test set RMSE (%) Current impact factor 0.8432 0.8454 19.6449 18.1043 Key Impact Factors 0.9325 0.9239 9.6117 8.8580

[0220] It can be seen from Table 7 that the fitting accuracy of the formula based on the existing influencing factors for the building surface irradiance is 84.5%, and the root mean square error is 18.1%, which is relatively low. If the accuracy threshold is set to 10%, the quantitative expression formula based on the existing influencing factors cannot meet the accuracy requirements and is not suitable for engineering applications. The fitting accuracy of the formula based on the key influencing factors for the building surface irradiance is increased to 92.3%, and the root mean square error is reduced by about 10%. Therefore, the key influencing factors of the building surface irradiance obtained by this analysis are more effective than the existing influencing factors.

[0221] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for analyzing key influencing factors of building surface irradiance, characterized in that: include: S1. Construct the factors affecting the surface irradiance of the building complex; S1.

1. Construction of new microscopic influencing factors of building complex surface irradiance: Construct weighted urban zenith angle WUZA: uniformly locate the azimuth ray beam to the south, and calculate the weighted urban zenith angle of the micro-element surface on the vertical building complex section corresponding to each ray beam; construct average incidence factor AIF: the solar incidence angle on the micro-element surface θ The cosine value of cosθ After calculation, the average value is taken as the average incidence factor; construct the weighted urban elevation angle WUHA: the azimuth ray beam is uniformly set to the north direction, and the azimuth angle of the azimuth ray beam in the horizontal plane is multiplied by the sine value to construct the weighted urban elevation angle; construct the environmental reflection factor EAF: the product of the angular coefficient of the micro-element surface solar reflected radiation and the reflectivity of the corresponding wavelength of the reflected radiation is taken as the environmental reflection factor; The calculation formula of weighted city zenith angle is: In the formula WUZA is the weighted city zenith angle; z for θ The zenith angle of the microelement surface under the azimuthal ray beam; θ is the angle between the projection line of the azimuth ray beam on the ground and the due east direction; When constructing the average incidence factor, the angle of incidence is negative. cosθ The value is 0; The calculation formula of weighted city elevation angle is: In the formula WUHA is the weighted city elevation angle; UHA θ for θ The city elevation angle of the microelement surface under the azimuth ray beam; θ is the angle between the projection line of the azimuth ray beam on the ground and the due east direction; The calculation formula of the environmental reflection factor is: In the formula EAF is the environmental reflection factor; GVF is the ground angle coefficient; BVF is the building angle coefficient; ρ g is the ground reflectivity; ρ b is the comprehensive reflectivity of the building complex; where the multiple terms of the reflectivity are based on the consideration of multiple reflections. Further summing up the geometric series, the calculation formula for the environmental reflection factor is: ； S1.

2. Analyze the correlation of influencing factors: The Pearson correlation coefficient r is used to assess the correlation between variables for the surface irradiance influencing factors of the micro-element surface of the building complex. The larger the correlation coefficient, the higher the linear correlation between the influencing factors, and the less suitable it is as the key influencing factor of the surface irradiance of the building complex. On the contrary, the smaller the correlation coefficient, the more suitable it is as the key influencing factor of the surface irradiance of the building complex. S2. Analyze the factors affecting the irradiance on the surface of the building complex: The total irradiance value of the micro-element surface is composed of direct solar irradiance, sky diffuse irradiance and reflected irradiance; among them, the potential key influencing factors of direct solar irradiance are the weighted urban zenith angle, the average value of the incidence factor and the average value of the direct solar radiation intensity; the potential key influencing factors of sky diffuse radiation are the sky angle coefficient and direct solar irradiance; the potential key influencing factors of reflected irradiance are the urban elevation angle, the weighted urban zenith angle and the environmental reflection factor; S3. Analyze the key factors affecting the surface irradiance of buildings; S3.1 Analyze the key influencing factors of the surface irradiance of the building complex: Use the building complex surface irradiance influencing factors to perform linear fitting on the annual average values ​​of direct solar irradiance, sky diffuse irradiance and reflected irradiance of the building complex micro-element surface, and finally take the single influencing factor with the highest fitting degree as the key influencing factor.

2. The method for analyzing key influencing factors of building surface irradiance according to claim 1 is characterized in that: The construction method of the building complex is as follows: firstly, a single building is constructed based on the design parameters of the single building, and then a number of copies of the single building are made according to the building spacing and staggered distance; Then, based on the building complex modeling parameters and meteorological files, all building design parameters are randomly sampled to model the building complex and complete the construction of the building complex model.

3. The method for analyzing key influencing factors of building surface irradiance according to claim 2 is characterized in that: In S1, when designing parameters for a single building, the base characteristic dimension is selected as the building width, and then the remaining dimensions of the building design are designed as multiples of the building width.

4. The method for analyzing key influencing factors of building surface irradiance according to claim 2 is characterized in that: The building complex model constructed in S1 includes: 500 training set building complexes and 100 test set building complexes.

5. The method for analyzing key influencing factors of building surface irradiance according to claim 1 is characterized in that: In S1.2, the correlation coefficient r The value of is between -1 and +1. 0≤|r|＜0.4 It indicates that there is a low linear correlation between the variables; if 0.4 ≤|r|＜0.7 It means that there is a significant linear correlation between the variables; if 0.7≤|r|＜1 This indicates that there is a high linear correlation between the variables.

6. The method for analyzing key influencing factors of building surface irradiance according to claim 1 is characterized in that: In S2, the total irradiance value is expressed in the quantitative expression process as: In the formula F dir,i For microelement surface i Direct solar irradiance; F dif,i For microelement surface i The diffuse sky irradiance of F ref,i For microelement surface i The reflected irradiance; F other,i For microelement surface i Other impact factors: The potential key influencing factors of direct solar irradiance are expressed as: In the formula WUZA i For microelement surface i The weighted city zenith angle; AIF i For microelement surface i The average incidence factor of DNI mean It is the average value of the direct solar radiation intensity in the meteorological file within the corresponding interval of the meteorological file library; The potential key influencing factor of diffuse sky radiation is expressed as: Where; SVF i For microelement surface i Sky angle factor; The potential key influencing factor of reflected irradiance is expressed as: In the formula UHA i For microelement surface i The city elevation angle; EAF i For microelement surface i Environmental reflectance factor; Rad mean It is the average value of radiation intensity in the corresponding interval in the meteorological file.

7. The method for analyzing key influencing factors of building surface irradiance according to claim 1 is characterized in that: In S3, the key factor of the annual average value of direct solar irradiance is the direct solar radiation composite factor, namely: In the formula I dir,i For microelement surface i The direct solar irradiance value is WUZA i For microelement surface i The weighted city zenith angle, AIF i For microelement surface i The average incidence factor, DNI mean It is the average value of the direct solar radiation intensity in the corresponding interval in the meteorological file; The sky angle factor SVF is the key influencing factor of the annual average value of sky diffuse irradiance, namely: In the formula I dif,i For microelement surface i The sky diffuse irradiance value is SVF i For microelement surface i Sky angle factor; The total horizontal irradiance value GHI is the key influencing factor of the annual average value of reflected irradiance, namely: In the formula I ref,i For microelement surface i The reflected irradiance value, EAF i For microelement surface i The environmental reflection factor, UHA i For microelement surface i The city elevation angle, GHI mean It is the average value of the total radiation intensity on the horizontal surface in the corresponding interval in the meteorological file; The total irradiance of the micro-element surface is the sum of the direct solar irradiance, sky diffuse irradiance and reflected irradiance of the micro-element surface, that is: In the formula I g,i For microelement surface i The total irradiance value; Since the direct solar irradiance, sky diffuse irradiance and reflected irradiance of the micro-element surface are not much different in magnitude, the key influencing factors of the three can be used together as the key influencing factors of the total irradiance value, namely: .

8. The method for analyzing key influencing factors of building surface irradiance according to claim 1 is characterized in that: S3 also includes S3.2 comparison of the effectiveness of key influencing factors: multivariate linear regression is used to fit the existing sample data of building surface irradiance influencing factors to explore the expression effect of the quantitative expression formula based on the existing building surface irradiance influencing factors on the building surface irradiance; among them, the existing building complex surface irradiance influencing factors are divided into geographical influencing factors, macro influencing factors and micro influencing factors; geographical influencing factors include season and region; macro influencing factors include building complex layout, orientation, building complex density, building complex floor area ratio and height-to-width ratio; micro influencing factors include sky angle coefficient, floor height ratio, reflectivity and urban elevation angle.

9. The method for analyzing key influencing factors of building surface irradiance according to claim 8 is characterized in that: S3.2 is as follows: Based on the multivariate linear regression analysis, x (i) The sample prediction formula is: In the formula, n is the number of attributes of a single sample; θ is the regression coefficient; x (i) For the i A sample of micro-element surfaces of building complexes; θ and x (i) It can be expressed as: Define the independent variable data set, dependent variable data set, and regression coefficient data set as follows: In the formula, m is the number of samples; n is the number of influencing factors; independent variable data set X∈ℝ m×(n+1) ; Dependent variable dataset Y∈ℝ m×1 ; Regression coefficients dataset θ∈ ℝ (n+1)×1 ; The solution of multiple linear regression can be transformed into: After solving, we get: Combined with the existing irradiance influencing factors, the regression coefficient matrix is: After solving the regression model based on the existing influencing factors, the expression formula of the building surface irradiance based on the existing influencing factors is formed; at the same time, based on the three key influencing factors of direct, scattered and reflected mentioned above, the regression coefficient matrix is ​​set as: The results after solution are compared; among them, θ 0 is the constant term of the multivariate linear equation, θ 1 is the sky angle factor, θ 2 is the building angle coefficient, θ 3 is the ground angle coefficient, θ 4 is the building density, θ 5 is the building complex volume ratio, θ 6 is the aspect ratio, θ 7 For the floor height, θ 8 is the city elevation angle, θ 12 is the comprehensive reflectivity of the building complex, θ 13 is the latitude, θ 14 is the longitude, θ 16 is the total irradiance on the horizontal surface, θ 17 is the direct solar radiation intensity, θ 18 is the horizontal sky diffuse irradiance, θ 19 is the solar direct radiation composite factor, θ 20 is the reflected radiation recombination factor.

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