Comparison of the use of data method and application system method

1 the origin of the problem

With the rapid development of China's economy, power shortage has become a national problem, and lighting energy conservation has also been highly valued.

However, in large-scale projects, the decorative design still has too many lamps and excessive lighting power density. The reason for the analysis is mainly because the decorative design is arranged by the designer of the decorative professional, and some of them often do not calculate the illumination. There is a general idea of ​​preferring to brighten the design without affecting the effect. Therefore, it is necessary for the decorative professional designer to master the method of illuminance calculation.

2Using the coefficient method and its deficiency

Usually, the calculation of the average illuminance is the application of the coefficient method, and the basic formula is:

Eav=μφNk A(1)

Where: φ―——the luminous flux of each light source in the luminaire (lm); N—the number of lamps; A—the area of ​​the working surface (m2); k—the maintenance factor; Eav—the work The average illuminance of the surface (lx); μ -- the utilization factor of the luminaire.

Use factor μ and lamp type (SL), lamp suspension height (hr), room area and shape (RCR), ceiling reflectance (ρc), wall reflectance (ρw), ground reflectivity (ρf), etc. The factor is related to the multivariate function of the above factors, and this functional relationship is often reflected in the form of a table. When calculating the illuminance, it is necessary to first check the utilization factor in the design manual by looking up the table. The process usually involves the steps of calculating the space ratio, finding the effective reflection ratio of the ceiling space, finding the average reflection ratio of the wall surface, and finding the utilization factor of the lamp. When the utilization factor is found, the illuminance calculation value Eav can be obtained by substituting into equation (1).

There are several problems in using the coefficient calculation method:

a. Where does the data on the luminaire utilization factor come from? Often, the data provided in the design manual is data from a few years ago, and it is difficult to provide new data on a regular basis.

b. The utilization factor is an approximate data. For example, in the process of knowing the space ratio of the chamber, the influence of the height of the lamp is not reflected. That is to say, the utilization factor reflects the ceiling of the lamp, and if the lamp is hoisted, The data when using the ceiling is approximated.

c. The calculation of the utilization factor is too cumbersome, so that some designers do not want to count even if they know the calculation method. Not to mention the non-electrical professional designers, it is not conducive to the promotion of the algorithm.

So, can you get a simpler calculation method for the main contradiction affecting the plane illumination?

3 fuzzy utilization coefficient method

If some mathematical processing is applied to the calculation formula using the coefficient method, the following formula can be obtained:

Em=μmPηsNkA"(2)

Where: ηs - "light source efficacy (1m / W); P - - the installation power of the light source (W); Em - the fuzzy average illumination of the working surface (lx); μm - lamps in a specific place The fuzzy utilization factor, see 1.

Comparing equations (1) and (2), it can be seen that there are mainly two differences:

a. Replace φ with Pηs, so the advantage of the alternative is that the designer does not have to find the luminous flux of the various types of light sources, because the power P is a necessary condition for characterizing the light source, and the light flux φ is not. At the same time, because the light source will have some differences due to the manufacturer, the materials used, the processing accuracy, etc., the data and actuality of the corresponding light source found will have certain errors. See the light efficiency index of common light source.

b. Replace μ with the blur utilization factor μm. The reason for this substitution is that in engineering design, the room area, space height, and facing materials that need to be calculated for illumination are determined by the building and decoration designers according to the room building function (Fr), and the types of lamps and light sources are electrical designers. According to the determination of the building function, it can be considered that parameters such as ρc, ρw, ρf, RCR, hr can be described as a function of Fr. When the building function of the room is determined, except for different types of lamps, the range of other parameters can be determined. Therefore, the main parameters affecting the utilization factor can be regarded as two, the type of lighting (S l) and the room building. Function (F r), the function expression is μm=f(S l,F r), and this function relationship is reflected in tabular form.

Example 1: There is a 10.8×7.2m conference room in a project with a ceiling height of 2.9m. It is planned to use 3×18W grille lights to distribute the lights at intervals of 2.4m.

The μm value corresponding to different functional rooms and common lamps in civil buildings Note: “―” indicates that the site should not be used with corresponding lamps or energy-saving requirements that are difficult to meet the lighting power density values.

2 light source light efficiency indicators

Using a three-primary fluorescent lamp, try to calculate the fuzzy average illumination of the room.

Solution: Check the table 1, 2: the three primary color fluorescent lighting effect ηs = 951m / W, its μm = 0.59 in the conference room; the maintenance factor is k = 0.8, the lighting layout is 3 rows and 4 columns, a total of 12, then:

Em=μmPηsNkA=0.59×3×18×95×(4×3)×0.8 10.8×7.2=374(lx)

Since the fuzzy utilization coefficient μm is an empirical data, it ignores some factors that affect the utilization of light, and it will cause a certain error in the average illuminance, so consider adding a correction factor.

Eav=μmPηsNkAKm%(3)

Where: K m --- fuzzy correction factor.

Equations (3) and (2) are the basic formulas and simple formulas for calculating the average illuminance by the coefficient method.

If Pηs is reduced to φ, then: E av = μmφNk AK m

(4)

Equation (4) is the exact formula for calculating the average illuminance by using the coefficient method. Comparing equations (1) and (4) can be seen: K m = μm

(5)

4The physical meaning of the parameters in the fuzzy utilization coefficient method

Compared with the coefficient method, the fuzzy utilization coefficient method proposes three new indicators, in which the light source efficiency is easier to understand, while μm and Km need to have reasonable physical meaning.

Since the fuzzy utilization coefficient method is derived by the coefficient method, μm is a special utilization coefficient, which reflects the average utilization coefficient of a certain type of lamp in a certain functional room under different room conditions. From the perspective of efficiency, it reflects the average efficiency of the lamps in a certain type of functional room when using certain types of lamps, which is a special embodiment of the efficiency of the lamps.

For example, in the classroom, the classroom shape of the classroom may vary widely, but if the most common classroom is 50 people, 12×7.2m, then we will use this type of room condition as a sample for different lamps. Using the method of calculation or actual measurement, the average utilization coefficient of different lamps in the classroom is the fuzzy utilization coefficient. In theory, it can only be used for the calculation of the average illuminance of the room with the same chamber shape index and the same veneer material. Under other room conditions, the utilization factor of the luminaire needs to be recalculated, but in the case where the accuracy of the contrast in the project is not high, It can be approximated that μm is the most probable occurrence of each utilization coefficient under such a room-shaped condition, so μ is used instead of μ when calculating a similar functional room of a similar room shape.

It can be seen from equation (5) that the blur correction coefficient K m reflects the efficiency ratio of the luminaire under a specific room shape and a standard room shape. For places with high illumination uniformity, the K m of different lamps should be relatively close. It can be approximated that K m is independent of the type of lamp and only related to the shape of the house. Therefore, K m can also be considered as the room shape correction coefficient. , its function form is K m=f(hr, ρc, ρw, ρf, RCR).

5 fuzzy use of coefficient method to make up for the defect

The fuzzy utilization coefficient method also has problems with data sources. Among the above three indicators, only the light source efficiency ηs can be obtained by the light source manufacturer, or directly calculated by the light flux to reduce the influence of the light source efficiency change; while the μm data in Table 1 is partly based on the data in the corresponding manual and the common room. From the calculation of the shape, the other is to use the statistical data on the reference materials and some empirical formulas, the conviction of the data will be questioned.

This problem should be considered in this way. From the physical interpretation of the fuzzy utilization coefficient method, it can be known that since μm is the most probable in the value of each utilization coefficient, then by investigating the utilization coefficient of enough existing rooms, the mathematical statistics method can be used. Find the mathematical expectation of μm; in the long run, if a new luminaire is put on the market, the quality supervision department can record the μm under the standard room shape, and the quality supervision department will build the corresponding standard room. Shape and evaluate whether the lamps are energy-saving, designers can obtain the corresponding information through the government website; and the data in Table 1 of this paper is the reference data, which is only suggestive.

As for K m, for the case of special room conditions, the corresponding relationship between the area, the space ratio of the room and the reflectivity of the facing material can be summarized by means of actual measurement or calculation, and compiled into a table for calculation of non-universal rooms. When used, the influence of K m can be ignored when designing a conventional room shape.

6 characteristics of fuzzy utilization coefficient method

The fuzzy utilization coefficient method provides three parameters related to efficiency: 1 source efficiency ηs, 2 in the standard room shape, relative to the specified illumination surface luminaire efficiency μm, 3 under non-standard room shape and standard room shape, relative designation The ratio Km of the luminaire efficiency of the illuminated surface.

It can be seen that the fuzzy utilization coefficient method has great flexibility compared with the use of the coefficient method, which is not easy to update data with development. When the light source efficiency has developed, or the new products of the luminaire appear, simply modify or expand the data in Tables 1 and 2. For example, if the light source of a certain LED light source is 501m/W in the future, and the fuzzy utilization coefficient of the corresponding lamp in the dance hall is 0.6, then the data can be added to Tables 1 and 2.

In this way, the development of light sources and lamps will not affect the calculation of illumination. If the design unit can determine the source and its efficiency, the designer can directly calculate the efficiency of the known source when calculating, instead of substituting the recommended efficiency into the formula. At the same time, the dynamic database of the new algorithm is also expressed in the design unit can directly obtain the data of the first-hand calculation parameters through the actual measurement of certain sampling data. If a design unit often designs a medical building, the unit can perform actual measurement in the built project, and use the obtained illuminance data and the optical communication data to calculate the fuzzy utilization coefficient, and then obtain the average value or expected value, which can be used as reference data for future projects. And when the data obtained by many units is aggregated through electrical magazines or associations, the calculated data with wider acceptance can be obtained.

In addition, these efficiency indicators can be used in the project to promote the implementation of energy conservation regulations. In the past decoration projects, the parameters affecting the utilization rate of the lamps were often determined by the decoration profession, but the electric designers considered the energy-saving problems. This formed a situation in which the responsibility was unclear, and finally the quality of the design was often affected. After adopting the fuzzy utilization coefficient method, through the regulation of μm, it can suppress the large-scale use of lamps with low efficiency such as marble lamps, and promote the selection of high-efficiency lamps; and improve the energy-saving awareness of decoration professionals through the regulation of K m , reduce the focus on the decorative effect does not pay attention to the room function requirements, such as the design of a small office in a decorative design, but also the use of poor reflective coatings, then, through the provisions of the K m minimum Can determine if this decorative design needs improvement.

After replacing the universal power of light, the important indicator of light source efficiency is not hidden behind the light, which can promote the use of high-efficiency light sources. Combined with the fuzzy utilization coefficient, it can quickly calculate whether the illumination power density (LPD) meets the requirements, which is the convenience brought by the fixed fuzzy utilization coefficient instead of the variable utilization factor.

If we make another variant of equation (2), then there are:

Ekμmηs=NPA=LPD(6)

In the formula: LPD--the lighting power density (W/m2) of the room, it can be seen that the lighting power density can be directly expressed by the formula containing the fuzzy utilization coefficient. Through formula (6), we can quickly check whether the lighting scheme of a room meets the lighting energy-saving regulations in the Architectural Lighting Design Standard (GB50034-2004).

Example 2: An office needs to be renovated. The lighting fixtures are intended to use grille lights. The lighting power density corresponding to ordinary fluorescent lamps and trichromatic fluorescent lamps is compared.

Solution: Look up Tables 1 and 2: μm=0.59 for the grille lamp in the office, ηs1=60"1m/W for the ordinary fluorescent lamp, and ηs2=95"1m/W for the trichromatic fluorescent lamp. Obtain E=300lx according to the specification: LPD 1 = E kμmηs1 = 300 0.8 × 0.59 × 60 = 10.6 (W / m 2) LPD 2 = E kμm ηs2 = 300 0.8 × 0.59 × 95 = 6.7 (W / m 2) visible, three primary color fluorescent lamps installed power than ordinary fluorescent lamps Less than 30%.

Usually, there is often more than one light source in the project, and the lighting power density can also be checked by equation (6).

Example 3: The decoration plan of a shopping mall business hall is planned to adopt half downlights and half spotlights. The corresponding light source is a compact fluorescent lamp and a quartz halogen lamp. It is determined whether the solution meets the energy saving requirements.

Solution: Check the table 1, 2: Compact fluorescent lamp ηs1=55%1m/W, ηm1=0.6 for the downlight in the mall, ηs2=25"1m/W for the quartz halogen lamp, ηm2=0.5 in the mall, according to the specification E=300lx, the equation (6) is transformed: LPD=E kμmηs=300 0.8×(0.6×55+0.5×25)/2=16.5"(W/m 2) and the lighting power of the general mall business hall is regulated. The density requirement is 12 W/m 2 .

Therefore, if the business hall neither uses mirror-like high reflectivity finish materials and other measures to improve the light-through utilization of the lamps, nor does it use a light source with higher luminous efficacy than the recommended light effect, the solution will not meet the energy-saving requirements. .

7 summary

The fuzzy utilization coefficient method is characterized in that its simple algorithm is highly implementable, and it can reduce the situation in which blind lighting is formed without calculating the illumination without using the coefficient and the light flux data. However, the simple algorithm of fuzzy using the coefficient method replaces the light flux with the light effect, and also increases the error caused by the light flux. As can be seen from Table 2, the range of the light effect fluctuation of the light source is large. If you can get the optical data in the design, you should still use the optical communication to calculate. If you can't get the optical data, you should add a note: if the light effect is greater than the recommended light effect, you can reduce the power of the light source. If the light effect is lower than the recommended light. Effective, you should increase the power of the light source.

In addition, since the parameters in the algorithm are empirical data or statistical data, and the fuzzy utilization coefficient is related to the selection of the most common room shape, the basic formula of the algorithm should be used in the case of more rooms in the project, because a large number of rooms will The probability that the most common room shape appears becomes larger; and the judgment of a single room involves the other two parameters "fuzzy correction coefficient" and "the ratio of the light source efficacy to the recommended light effect", if the basic formula of the algorithm is adopted When calculating, it can only be used in places where the illumination accuracy is not high, and for the calculation of illumination such as important stadiums and other places, professional software should be used for calculation.

The fuzzy utilization coefficient method is only an empirical algorithm summed up from individual projects. Whether it is reasonable or not is still to be verified by more engineering practice. In particular, the selected values ​​of the parameters in the algorithm need to be adjusted after more actual measurement. Received criticism and suggestions from a wide range of colleagues to promote the development of illuminance calculations.

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