Page 191 - AJWEP-22-6

Municipal street lighting retrofit in Bulgaria

Figure 6. Lighting classification of the street network in the town of Pavlikeni in accordance with EN 13201

Table 2. Standard lighting performance indicators Table 3. Standard lighting performance indicators
for lighting classes M4, M5, and M6 for lighting class P6
Lighting Road surface Threshold Surround Lighting class Horizontal illuminance
class luminance increment ratio E avg, lx E min lx

,
L avg, U U f , % R Р6 ≥2.00 ≥0.40
cd/m 2 o l TI EI Notes: E avg: Average horizontal illuminance; E min: Minimum
M4 ≥0.75 ≥0.40 ≥0.60 ≤15 ≥0.30 horizontal illuminance.
M5 ≥0.50 ≥0.35 ≥0.40 ≤15 ≥0.30
M6 ≥0.30 ≥0.35 ≥0.40 ≤20 ≥0.30 and 8. The technical characteristics of the LED street
Notes: f TI: Glare index; L avg: Average luminance; R EI: Surround luminaires, including the range of possible settings for
ratio; U l: Longitudinal uniformity; U o: Overall Uniformity. electric power, luminous flux, and luminous efficacy,
are presented in Table 4. These characteristics are
2.2.2. Optimization of street lighting design utilized in the lighting calculations for Pavlikeni and
The energy efficiency of LED technology in lighting Byala Cherkva.
fixtures has steadily improved in recent years, According to the technical specifications prepared
reaching high yet variable performance levels. by the municipality of Pavlikeni, and to minimize
A wide range of luminaires with differing luminous investment costs in the modernization of street
flux outputs and light distribution characteristics is lighting, it was specified that the new LED lights
currently available on the market. In this study, two should be installed only on existing poles. This
types of LED luminaires with luminous efficacy requirement was supported by the findings of the
exceeding 120 lm/W and distinct light distribution comprehensive energy audit, which confirmed the
characteristics were proposed, as required by satisfactory condition of the electrical supply network
the contract with the municipal street lighting utilized for street lighting. The cost of implementing
maintenance company, as illustrated in Figures 7 the project would be more than 10 times higher if the

Volume 22 Issue 6 (2025) 185 doi: 10.36922/AJWEP025310242