Road lighting standard comparison and energy saving analysis

At present, the research on road lighting energy-saving methods at home and abroad is mainly reflected in the following two aspects: First, the use of high-quality and efficient new light source to replace the traditional light source, such as the “Ten Cities and Ten Thousand Plan” launched by the Ministry of Science and Technology in 2009 is to make full use of The huge energy-saving potential of LED light source is gradually replacing the traditional light source such as high-pressure sodium lamp, that is, focusing on the design of LED light source and luminaire; on the other hand, it realizes on-demand illumination according to the requirements of road lighting in different time periods, such as early adopting after midnight. Half of the light source to achieve power saving effect, the recent research uses intelligent dimming technology, Internet of Things technology to achieve automatic control of light source intensity in different periods to achieve lighting energy saving. Both of these methods are road lighting energy-saving design from the level of engineering implementation, ie tactical level. The premise must meet the existing road lighting design standards, which means that road lighting design standards have a crucial impact on lighting energy efficiency. . If the standard requirements are too high to affect the level of energy conservation, if the standard requirements are too low, it will affect driving safety. Therefore, starting from the road lighting design standards, it is necessary to study how to make the standard itself more conducive to energy saving under the premise of ensuring road lighting safety. It has a deeper significance in the research of road lighting energy saving. This research work can carry out road lighting. Energy-saving research has risen from a tactical level to a strategic level, enabling greater energy savings.

The formulation and research of national road lighting design standards by countries generally refer to international road lighting design standards based on the actual situation of existing road traffic. At present, there are two major standards systems in the world. The first is the Road Lighting Recommendations for Motor Vehicles and People Traffic (115-1995) proposed by the International Commission on Illumination (CIE). It is the vast majority of countries in the world. Adopted; the second is the Road Lighting (RP-8-00) [8-9] proposed by the Illuminating Engineering Society of North America (IESNA), which is mainly used in the Americas. Both sets of standards are comprehensively balanced between the two aspects of road safety and energy saving, and have been promoted on a considerable scale, but for the similarities and differences between the two sets of standards, the international only There are some qualitative comparisons. As for the main differences between the two types of standards in evaluation methods, lighting indicators, energy-saving effects, etc., there is still a lack of quantitative and in-depth research. Therefore, an in-depth analysis of the quantitative differences between the two standards in the evaluation indicators and calculation methods and the related lighting effects and energy consumption differences, has a greater engineering guiding significance for promoting energy conservation and emission reduction from the strategic level of road lighting standards. And scientific value.

2. Comparison of two road lighting design standards

2.1 Recommended road lighting recommendations by the International Commission on Illumination (CIE)

In CIE115, motor vehicle roads are divided into five categories, M1~M5. The road lighting quality is evaluated by the average brightness, total brightness uniformity, brightness uniformity, environmental ratio and threshold increment of glare evaluation. The evaluation content and indicators The details are shown in Table 1.

2.2 Road lighting design standards proposed by the North American Lighting Engineering Association (IESNA)

In the American road lighting design standards, roads are divided into six categories according to road complexity and traffic volume. For each type of road, the high, medium and low grades are set according to the different materials of the road surface and the size of the traffic. Evaluation index specified value. IESNA has proposed three types of road lighting evaluation indicators, designers can choose the appropriate indicators to design according to needs. The three types of indicators are illuminance indicators (including average illuminance and illuminance uniformity), brightness indicators (including average brightness, brightness uniformity, and brightness longitudinal uniformity) and small target visibility indicators. Among them, the illuminance index and the brightness index all contain the brightness ratio index of the light curtain for evaluating glare, and the specific contents and indicators are shown in Table 2.

2.3 Comparison of road lighting design standards

2.3.1 Qualitative comparison

According to the CIE and IESNA two types of road lighting design standards, the difference between the two types of standard motorway lighting design standards can be found in the following three points:

The first is the selection of evaluation indicators. The CIE mainly uses the brightness index to evaluate, including the threshold increment TI and the environmental ratio SR index. The IESNA uses three indicators, namely the illumination index, the brightness index and the small target visibility index STV, among which the illumination index and the brightness index are used. The light curtain brightness ratio indicator is included to evaluate glare.

The second is the calculation method of the evaluation indicators. The main difference is reflected in the calculation of the brightness index. The CIE specifies that there is only one observer in each lane and is fixed at 60 meters behind the starting position of the calculation area to observe the brightness of all matrix points in one lamp cycle (as shown in Figure 1). IESNA specifies that each row of the matrix in the calculation area has an observer, and each observer always observes the brightness of the matrix point 83 meters ahead of the direction of the matrix (as shown in Figure 2), meaning IESNA The observer in the standard performs lateral movement not only in the direction perpendicular to the lane but also in the direction of the parallel lane.

The third is the definition of the evaluation indicators and the specified values ​​of the indicators. For average brightness, total brightness uniformity, and brightness uniformity, CIE and IESNA are exactly reciprocal in their definition, and numerically, the CIE standard specified by the same indicator is significantly higher than the IESNA standard, as shown in Table 1 and As shown in Table 2, it can be seen from the table that the average brightness of the IESNA is 60% of the CIE, and the brightness uniformity is 82% of the CIE requirement.

2.3.2 Quantitative comparison

In order to quantitatively analyze the differences in the brightness calculation methods of these two types of standards, five typical road lighting fixtures of PHILIPS (the distribution of light distribution and optical parameters are shown in Figure 3) were selected, and four lanes of different widths were selected. The combination of 20 lamps and roads (shown in Figure 4 and Table 3) of the three lamp installation methods is calculated, and the difference between the brightness index values ​​of the CIE standard method and the IESNA standard method under each combination is obtained (as shown in Fig. 5). Show). In Fig. 5, the abscissa indicates 20 combinations of different lamps and lane widths, and the ordinate indicates the difference in average brightness, total brightness uniformity, and brightness longitudinal uniformity obtained by the brightness calculation methods defined by CIE and IESNA, respectively. relative value. It can be seen from the figure that the average brightness value and the brightness longitudinal uniformity value of the two types of standard calculation methods are not much different, and the longitudinal uniformity of the brightness obtained by the IESNA calculation method is substantially larger than the value obtained by the CIE method. The total brightness uniformity value is significantly larger than the value obtained by the CIE calculation method. This means that the IESNA standard method of designing luminaire layouts is easier to meet the standard requirements at lower energy consumption than the CIE standard approach.

3. Quantitative comparative analysis of energy consumption under different standards

Since different lighting installation parameters caused by different calculation methods and specified values ​​of road lighting standards will affect the difference in energy consumption, the optimization method is used to optimize the installation conditions of the lamps under the different standards of the above 20 combinations. For the sake of unification, both types of standards use the brightness index to optimize the design of road lighting, taking into account the glare evaluation index. Different installations are optimized by different standards to obtain different installation intervals S, combined with the power W of different lamps, the same road can be obtained. The difference in energy consumption △E under two types of standard guidance design. In the optimized design, it is assumed that the road length required to install the streetlights in each combination is 1000 meters. According to the optimization calculation results, the number of single-sided lamps required for each combination of the two types of standards is shown in Fig. 6. The difference in energy consumption is expressed by the ratio of the difference between the energy consumed by the CIE and IESNA standards and the energy consumed by the CIE standard optimization. The results are expressed as a percentage as shown in Fig. 7.

It can be seen from Fig. 6 that with the IESNA standard regulations and calculation methods, the number N of single-sided lamps used in the same combination is much less than that of the CIE standard. As can be seen from Fig. 7, the calculation method and regulations of the brightness in the IESNA standard are compared with the design of the CIE standard, and the energy saving rate is at least 10%, and the maximum is close to 30%. Taking the urban roads and highways of a city as 5×104 km, the difference in energy consumption between the two is quite large under the premise of meeting the requirements of the respective indicators.

In order to replace the energy-saving effect with the lamps that are currently in the mainstream energy-saving mode, this paper takes a 1000-meter three-lane two-way symmetric lamp motorway as an example, under the same road lighting design standard (taking the CIE standard as an example), A PHILIPS LIM Fortimo LED luminaire replaces the HPL-N80W high-pressure sodium luminaire (Figure 8 is the light distribution and optical parameters of the two luminaires), which can be optimized by the road lighting grading design. The number of lamps used and the amount of energy consumption are shown in Figure 9. It can be seen from the figure that for this section of the road, because the luminous flux of the LED luminaire is small, the sodium luminaire is directly replaced by the LED luminaire. To achieve the same lighting requirement, the number of lamps required will increase by 25%, and the power of the LED luminaire is far. It is much smaller than the power of the high-pressure sodium lamp, so the energy consumed can be reduced by 58.3%.

If further combined with the impact of different road lighting standards on energy saving, this LIM Fortimo LED luminaire is optimized for road alignment with the IESNA standard for the three-vehicle road segment, resulting in the number of lamps and energy consumption and the results of previous high-pressure sodium lamps. Compared to Figure 10. Compared with the replacement of individual lamps under the same standard, when the LED lamps are optimized with the IESNA standard, the number of lamps used and the number of lamps of the high-pressure sodium lamp under the CIE standard are reduced by 6.2%, and the energy consumption can be further reduced. 68.8%. Compared with the previous direct replacement with the same standard, the replacement cost of the luminaire is reduced by 24.8% due to the reduced number of LED luminaires used. The energy consumption of LED lighting energy can be reduced by 25% under the guidance of the IESNA standard.

It can be seen that the IESNA road lighting design standard for road lighting distribution optimization, the energy consumption is generally lower than the energy consumption brought by the CIE standard, combined with the efficient way to replace the traditional lighting fixtures with high-efficiency LED lamps, you can The energy reduction method is promoted from simple engineering energy conservation to standard energy saving, thereby maximizing energy conservation.

4. Conclusions and recommendations

The purpose of the standard study is to find the best balance between ensuring driving safety and energy saving and environmental protection based on actual conditions. China's existing "road lighting design standard CJJ-2006" uses illumination evaluation indicators such as illuminance, brightness, threshold increment of glare evaluation and environmental ratio on the evaluation index. In terms of calculation methods and index values, the main reference is The calculation method and index value of the CIE standard have taken into account the issue of driving safety.

Through the quantitative calculation and analysis of CIE and IESNA, they have some differences in evaluation index, calculation method and index value, and the requirements of CIE are slightly higher than IESNA, so the road lighting design is used in these two standards. In the same situation, the road surface illumination effect based on CIE is slightly better than the IESNA standard, which is more favorable for ensuring driving safety; in the same case, the number of lamps required for luminaire layout optimization based on IESNA standard is significantly less than that of adopting CIE standard, ie Using the IESNA standard to guide the installation of road lighting fixtures can reduce energy consumption by at least 10% compared to the CIE standard, which is beneficial for energy saving and emission reduction and prevention of light pollution.

The above quantitative comparison is only a theoretical calculation result, and further in-depth research is needed. Therefore, it is recommended to give due consideration to the improvement of road lighting design standards in the future. Due to the wide geographical area and large urban differences in China, it is not suitable for a one-size-fits-all approach. Therefore, whether the study of standards can be treated differently: For some areas with a wide geographical area, such as the western frontier, you can consider trying to use the IESNA standard method to define And determine the value of the indicator; but for areas with relatively dense population and relatively complex roads, such as the central and eastern regions, it is necessary to implement CIE standards and ensure a high level of lighting.