Proiezione natalizia Piazza Duomo a Trento
Okay, we are in an energy emergency. We turn everything off“.

Who among us has not thought this while watching television, surfing social media, comparing ourselves to our armchair neighbor at the barber shop? But while the question is legitimate, the answer is not so obvious: in the field of architectural lighting, appearances are deceiving.

In fact, an analysis of reliable and objective data can, undoubtedly, help us to understand the actual incidence of the costs of lighting setups, relative to electricity consumption. To dispel any doubts regarding economic impact, it should be kept in mind that

a goboprojector is capable of illuminating 150 square meters of a building facade for 8 hours, at a cost of 1 Euro per day

A 250 W LED projector such as the “Divum 30k” allows a 150-square-meter facade to be illuminated for 8 hours a day for 30 consecutive days; a time frame that roughly covers the entire course of the holiday season. Well, taking into account that the cost for energy is 0.5€/KWH, at the end of the period corresponding to about a
month, the economic burden to be borne will be negligible, standing at just 30 euros.

How much does each of our goboprojectors consume?

On the following page(, you can calculate the energy consumption of our projectors.

Having demonstrated that architectural Christmas illuminations do not, in fact, give rise to significant economic returns, the issue we should instead address, in its complexity and generality is:

how we can reduce the energy consumption of cities in a a truly significant way?

First of all, it should be noted that a city of about 100,000 inhabitants, in Italy, spends an average of 2.87 million euros per year to support public lighting bills and that the per capita consumption for public lighting in Italy is 28.7 euros/year source(

Then there are virtuous realities in our country, such as the Municipality of Trento, which has been investing in the conversion of public streetlights to LEDs for some time now, saving more than 150,000 euros per month. Trento (population 117,000) spends 1.2 million euros per year for street lighting, so 100,000 euros per month source (

Thanks to the adoption of new green strategies and policies, the city of Trento has implemented a more efficient public lighting system, recording a per capita consumption of 10.2 euros/year: one third of the national average value.

The energy cost of Christmas architectural projections in Trenton

In 2021 Goboservice illuminated, in Trento, the city’s Christmas with a project that involved as many as 80 Divum 30k projectors. The energy cost related to the use of the floodlights was 1,920 euros per month, less than 2 percent of the cost of public lighting in the municipality of Trent for the same period.

The City Council, once again this year, decided to illuminate the city through Christmas mappings, without sacrificing energy consumption savings. The projection will take place in Cathedral Square: public lights will remain off and the lighting of the area will be entrusted exclusively to photomapping. The adoption of this strategy, will result in significant energy savings since traditional floodlights illuminating downtown buildings consume 5.1 kW/h, unlike photomapping which consumes only a third (1.7kW/h). In addition, the reduction in the lighting hours of the illuminations will bring, compared to the previous year (100 fewer total hours), a further reduction in costs.

To make it even more immediate comparison between the energy choices to be pursued, we then try to represent in a graph the economic impact on a city like Trent, which has made a forward-looking investment in terms of infrastructure endowment, innovating the own installations with LED lamps and that on a city of equal density housing, which remained anchored to traditional lighting systems.


It becomes…glaring how the choice to replace public facilities
lighting with energy-efficient elements is the way forward toward a
Real and lasting savings.

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