More efficient public lighting in Karlovac, Croatia, thanks to Smart Energy Performance Contracting

The city of Karlovac is located in central Croatia, at the meeting point between the Croatian lowlands, Croatian highlands,  Pokupje, and Kordun. Karlovac is framed by four rivers – Kupa, Korana, Dobra, and Mrežnica. Located in the narrowest part of Croatia, it is only 50 kilometres away from neighbours Slovenia and Bosnia and Herzegovina. As a city, Karlovac has an important traffic and economic significance. 

Karlovac is one of the rare cities that know the exact date of their creation. For Karlovac it is July 13^th 1579, when it was also named by its founder, archduke Karl von Habsburg. This moment marked the beginning of construction of the Karlovac border military fort, built for the purpose of defence against the Turks.  

In 2023, on September 23^rd, the city of Karlovac has signed its Energy Performance Contract (EPC) for the refurbishment of the public lighting. The scope of the contract is the refurbishment of overall public lighting, consisting of 9.083 luminaires and the displacement of 152 public lighting cabinets that are placed inside the DSO transformer station.

The city has many different luminaire types; within the Smart EPC contract the emphasis is placed on the preservation of the city’s visual identity (Figure 2). Next to road lighting luminaires, within the scope of the contract are also urban park luminaires, architectural floodlighting, public sport field lighting, and underpasses lighting. 

Besides visual requirements, the contract also included strict light pollution requirements such as max CCT, G-index, ULOR and maximum illuminances. After the refurbishment, the city lighting will be fully harmonised with the Croatian national law against light pollution. Within the Smart EPC contract, the city defined strict lighting quality requirements that are in accordance with the EN 13201 European standards and the national legislation.  

When preparing for the EPC tendering, Karlovac has carried out a detailed energy audit of the public lighting and has defined lighting profiles (defining geometrical parameters) for every lighted area of the city. Special attention was put on the lighting of the conflict zones (Figure 3).  

The costs of the data transfer (luminaires-software and vice versa) are also included in the contracted fee. The contract also accommodates the development of the management software for the public lighting, but also of the contract stipulations. The management and monitoring software will have functionalities for:  

• Display of the public lighting elements static data (e.g. luminaire type and model, date of the installation, road classification); 
• Processing and display of dynamic data obtained from luminaires (power, alarms, voltage); 
• Archiving of collected data; 
• Display and visualisation of public lighting system; 
• Sending data to the luminaires; 
• Alarming by logical conditions; 
• Reporting on the key public lighting performance or other indicators; 
• Controlling, supervision, and reporting for the Energy Performance Contract management. 

The contracted private partner has 2 months to finish designing the public lighting refurbishment and to develop the conceptual design for the management and control centre.   

The refurbishment phase, when all luminaires need to be replaced and all other works to be finalised, is 12 months from the moment of contract signing. After the completion of refurbishment, the usage phase starts, lasting for 10 years. 

The project in numbers: 

Written by Marko Miletić, REGEA Energy Agency