# Efficiency Analysis of Roadway Lighting Replacement in a Selected Polish Municipality
## 3 Results
### Projected Maintenance Costs for LED Lighting  
According to the manufacturer's declaration, savings achieved with LED lamps are up to 70% compared with the use of discharge lamps. As this is the upper limit of the potential savings, for the purposes of the study, it was assumed that after replacing the old luminaires with LED luminaires, energy consumption would fall by 55% (the average reduction value resulting from the tests of differences declared by dimmer manufacturers is about 15-25% savings compared to systems without dimmers) and, if automatic light intensity reduction is used at night, by 70%. The projected cost of electricity consumption in the first year after installation of the LED luminaires is estimated as follows:  
Energy price (Euro/MWh) \(\times\) Lighting time (h/year) \(\times\) Power (MW)  
It is also assumed that energy costs will increase in the same way as for discharge lamps, i.e., as a geometric sequence where each successive amount is 103% of the previous amount.  
In addition to the monthly planned costs, the maintenance costs for luminaires also include additional costs, mainly depending on the wear and tear of the fixtures. It is assumed that the additional maintenance costs for new LED luminaires will be very similar to the corresponding costs for new HID luminaires. Like the energy consumption costs for a new network with HID luminaires, these costs will be calculated based on a decreasing geometric sequence.  
The graph (Figure 2) illustrates the operating costs for the old system without investment costs and the operating costs for subsequent variants with investment costs.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Item No.** & **Specification** & **Units** & \
\begin{tabular}{c} **Number of** \\ **Units** \\ \end{tabular} &
\begin{tabular}{c} **Price per** \\ **Unit** \\ \end{tabular} & **Price** \\ \hline
1. & Labour & r-g & 4.86 & EUR 8.92 & EUR 43.34 \\
2. & Means of transport & m-g & 2.01 & EUR 18.28 & EUR 36.74 \\
3. & Mobile crane & m-g & 2.05 & EUR 33.27 & EUR 68.20 \\
4. & Logging truck up to 10 t & m-g & 0.55 & EUR 27.42 & EUR 15.08 \\  & & Total & & EUR 163.37 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Material expenditure for dismantling a reinforced concrete pole per pole, taking into account the nature of the planned works.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Variant** & **A1** & **A2** & **B1** & **B2** \\ \hline V1 & EUR 924,411 & EUR 946,191 & EUR 1,023,429 & EUR 1,047,087 \\ V2 & EUR 928,629 & EUR 950,409 & EUR 1,027,647 & EUR 1,051,305 \\ V3 & EUR 938,788 & EUR 960,569 & EUR 1,037,806 & EUR 1,061,465 \\ V4 & EUR 843,427 & EUR 865,207 & EUR 942,445 & EUR 966,103 \\ V5 & EUR 845,325 & EUR 867,105 & EUR 944,343 & EUR 968,001 \\ V6 & EUR 830,670 & EUR 852,450 & EUR 929,688 & EUR 953,346 \\ V7 & EUR 833,749 & EUR 855,530 & EUR 932,768 & EUR 956,426 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Total costs for installation and dismantling of lighting poles.  
NPVs were also determined for the various options (Table 8).  
The best option in terms of investment and operating costs is the B1V6 variant--BGP292 73 W 4000 K 10440 lm IK08 IP66 LumiStreet Philips LED street lamp with dusk dimmer, mounted on ZN reinforced concrete poles, e.g., ZN 9/202 with the UP1/ZN system.