Street lighting

Street lighting is an important part of every city in terms of guaranteeing citizens a safe living environment. At the same time, road and street lighting makes up an estimated 2% of electricity consumption across the world.

Energy efficiency is receiving more and more attention in Europe. Good solutions for better lighting control are being sought and lighting technology is being upgraded. In some areas outdoor lighting makes up nearly half of the regional budget.

Economical LED lamps with smart lighting control solutions can help local authorities attain energy savings of up to 85%.

In recent years, the city of Tartu has made its street lighting more economical and environmentally friendly. On streets with higher traffic, nearly 1500 lights have been replaced (10-11% of the total number of street lights), more than half of which are radio controlled LED lamps.

In the future, lighting can be integrated with various sensors (environmental, motion, parking, noise and other detectors) and technical solutions (security cameras, Wi-Fi base stations, etc.).

Future smart street lights will be able to understand their environment and adapt to the conditions.

The purpose of the upgrades is to develop a sustainable, economical and multifunctional street light network that meets the technical standards with a smart control system.

In 2014, Tartu had 321 km of illuminated streets lit by 11,547 lamps. The lamps are connected by 227 km of overhead power cables and 126 km of underground power cables. The lamps are controlled via 151 control panels. 10,620 of the lamps in use in Tartu were HPS lamps, which were supplemented with 295 HID lamps and 632 LED lamps. 10% of the energy consumed by street lights was generated from renewable sources. In 2015, this figure was 20%.

Table 2.21. Street lighting energy consumption in Tartu’s districts in 2014

In 2010, Tartu’s street lighting electricity consumption was 7.456 GWh. By 2014, it had dropped to 7.361 GWh. The decrease in consumption was minimal – merely 95 MWh. The use of new LED lamps has not yielded significant reductions in street lighting energy consumption mainly because over time several new streets have been added (e.g. Idaringtee), which has increased the number of street lights.

Street lighting energy consumption in Tartu is highest in the district of Annelinn and in the city centre (see Table 2.21). These areas account for 25% of the city’s total street lighting energy consumption, with combined consumption of 1.867 GWh. Annelinn and the city centre contain a total of 2,971 lamps and 46 control panels.

Street lighting energy consumption is seasonal, as shown in figure 2.7.

In 2015, 600 of the most powerful HPS lamps were replaced with new, energy-efficient LED lamps. At the beginning of 2017, Tartu’s street lighting included over 1200 LED lamps. Within the next nine years, Tartu City Government aims to replace all remaining HPS and HID lamps with LED lamps.

To do this, the city has been divided into nine lighting districts (see Figure 3.4). These districts are comparable in terms of size, number of lights and control panels and energy consumption. Each year for the following nine years, all of the street lights in one lighting district will be replaced.

The estimated energy savings from replacing HPS lamps with LED lamps are 70%. Actual energy savings will depend directly on the power and location of the lamps. According to calculations, at average energy savings of 70%, the payback period of these replacements is eight or nine years.

Table 3.3. Tartu city street lighting energy consumption per district in 2010, 2014 and 2020 (unit: MWh; 2010 data per district not available).