# Efficiency Analysis of Roadway Lighting Replacement in a Selected Polish Municipality
## 5 Discussion  
The authors [21] developed a trust-based distributed sensor selection architecture for urban road networks under the requirement that the brightness of street lamps is maintained at the lowest admissible level. Simulations conducted to evaluate the potential energy savings have shown the efficiency of the proposed approach to be up to 70% when contrasted with traditional street lamp systems. In turn, the authors [17] state that, according to their research, the local government in Jakarta successfully reduced electricity bills for street lighting systems from USD 200,000 to USD 108,000 per month, i.e., by almost 50%. According to [22], LED ballast and control node regulation precision for a 'dimming profile' algorithm can be improved, as it shows rather wide variations in the real illumination values on the street and can give 8-10% energy savings. [PERSON] et al. [15] evaluated the replacement of 193,045 conventional street lighting luminaires with LED ones. They reported that the annual energy savings amounted to 70%. The paper shows that the project value obtained in the analysis adapted to the case study is higher than that obtained in the traditional analysis since the latter optimistically assumed a constant rate of electricity costs over the long lifetime of the LED packages. According to the literature review, the benefits can range from 50% to as much as 80% savings, depending on the selected lighting system and the use of automatic dimmers and motion sensors that switch on/off or regulate light intensity. The authors' original research has shown the high efficiency of and quick return on the investment consisting in the replacement of road lighting poles. The results presented in the paper contribute to the general research on the efficiency of LED road lighting. However,it should be noted that road safety also constitutes a significant factor, which is often overlooked by many researchers when calculating the efficiency of solutions. They propose solutions consisting of switching off some street luminaires and introducing dimmable lighting and motion sensors. However, the statutory lighting standards in Poland and other European Union countries define the parameters that proper street lighting must meet. Maintaining lighting at the level set out in the standard helps to ensure the safety and comfort of the residents, road and street users in particular. It is, therefore, clear that seeking to reduce costs by, for example, partially switching off street luminaires not only fails to solve financial difficulties but also generates numerous complications and problems. Switching off every second or third luminaire, for example, will automatically result in non-compliance with the lighting uniformity and luminous flux parameters specified in the lighting standard. Therefore, the analysis aims not only to reduce costs but also to ensure lighting comfort and uniformity. Many projects are optimized with digital tools. The aspect of roads is very important for any well-functioning city [23]. Properly lit roads create user comfort. With the right selection and consideration of optimum lighting solutions, future problems with the reconstruction and expansion of existing infrastructure can be avoided. Structural elements used during the construction of new roads can be reused for the installation of new luminaires in the future. Thus, it will not be necessary to demolish the entire infrastructure. Such possibilities for storing digital data, including historical records, and the easy replacement of selected road lighting elements without having to design them from scratch are offered today by the BIM models. The data used in the analysis can be stored in IFC files for future use [24]. IFC files contain the data provided by the commissioning authority and the author of the project. Standardisation should be taken into account when creating IFC files as it is the standards that enable the necessary data to be accessed and used efficiently.