As of August 29, 2022, the municipality manages a total of 143,466 light fixtures in the territory of Prague. But this does not mean that the city has the same number of street lighting poles. There can be more lights on one mast. The most typical variant is the legendary sodium discharge lamps, which glow orange. They make up the vast majority of all lights in Prague, numbering 134,149. Estimated costs for providing energy for public lighting this year will be around 250 to 300 million crowns.

“They don’t even have that glow in Vienna!”

The orange shade of light is associated with high-pressure sodium lamps. “Their widespread use in public lighting was conditioned by the fact that it was the most efficient light source at the time,” Tomáš Novotný, vice-chairman of Technology of the Capital City of Prague, tells Bleska. However, if a Prague citizen walks under a lamp, he will not be able to distinguish colors very well. In addition, electrocardiography cannot be dimmed with classical lamps. Their production will end within a few years due to the low mercury content.

The European Union wants to limit the use of high-pressure sodium discharge lamps containing poisonous heavy metal along with other dangerous substances. The production of discharge lamps for public lighting is said to have practically ended. “That’s why there is now a need to accelerate the discharge lamps to the lamps with light recovery diodes (LED), which can install a new level of comfort for us,” adds Tomáš Novotný.

End of an era

“Yes, that sodium orange glow is currently typical for Prague, but it is necessary despite the fact that it is not an ‘ideal color of light,'” comments Tomáš Novotný. The THMP is based on the upcoming Public Lighting Concept of Prague, which is being prepared for the city by a multidisciplinary team of experts that analyzes the needs of the city and its residents. “The basic color tone of light for Prague is warm white. There must be a valid reason for using a different color tone, vs. the concept is, for example, the lighting of crossings for risky pedestrians or otherwise for traffic,” informs Tomáš Novotný.

The Prague UNESCO Heritage Zone also has specific conditions, as do specially protected areas. In addition, the current warm white color will be more in line with the historical tradition of Prague streets. “If, for example, we look into the history of picturesque gas lamps, the light of which is not orange. Their light is warm white with a color temperature of approx. 2700 K, i.e. more in line with the color tone set by the Concept today,” says the vice-chairman. There are currently 417 gas masts in the city, on which there are 663 gas lamps.

The future is bright for LED lights

Prague’s lighting is slowly being modernized. There are currently 9,317 lamps with LED chips in Prague, but their number will increase. Some Prague residents still remember the previous change of lights. “Those who have witnessed it know that the first sodium discharge lamps in public lighting caused the same resistance as the first generation of LEDs with a cool white light tone. Until then, there were people who could distinguish colors under public lighting, from mercury lamps,” says Tomáš Novotný. If the new lights used chips with an orange color tone, they would not be as energy efficient as warm white.

However, cool white light must not be used, as it can have a negative effect on ecosystems in connection with the content of the blue component of light. “Choosing a warm white tone of light thus comes out as a reasonable compromise, especially at a time when energy savings are once again the number one societal issue,” concludes Tomáš Novotný.