Reducing floodlight energy costs: LED versus HQI

Annual costs = connected load in kW × operating hours per year × electricity price in € per kWh. You need three values from your installation:

• Connected load: number of floodlights × system power per floodlight, for HQI including the ballast
• Operating hours: all hours with the light on, including warm-up
• Electricity price: from your bill, not from an average value

Calculate this once for the current installation and once for the LED installation. The difference is your electricity saving. With a lighting calculation and datasheet, the new connected load can be determined for your pitch.

Warm-up counts: in the practical example of the Stadtwerke Troisdorf, metal halide floodlights need about 20 minutes to reach full brightness and up to 30 minutes to restart after being switched off. LED floodlights light up instantly.

The association guide of the football associations of Saxony, Saxony-Anhalt and Thuringia shows the refurbishment of a pitch in lighting class III with six masts: 8 HQI floodlights with 2.2 kW system power each, i.e. 17.6 kW, became 8 LED floodlights with 0.911 kW each, i.e. 7.288 kW. That is around 59% less connected load.

In 2017, the City of Mainz calculated for a sports pitch with a power difference of 8 kW and 500 operating hours per year. That gives 4,000 kWh less per year. Only your own calculation shows which values apply to your installation.

These are values cited by municipalities and authorities, some planned, some achieved:

• City of Eschweiler: more than 75% on average, 76.82 to 79.17% per installation
• SV Eiche Reichenbrand, Chemnitz, according to klimaschutz.de: around 72%, more than 15,500 kWh per year
• City of Völklingen, 13 sports pitches: over 60%, more than 120,000 kWh per year
• City of Troisdorf, Sportplatz Bergheim: 60%
• City of Speyer, Sportplatz West: 50.68%
• City of Wuppertal, Sportplatz am Nocken: 40 to 50%, with an increase from 120 to around 200 lx
• City of Münster, 28 sports facilities: connected load from 760 to 225 kW, around 70% less

The range is explained by the old installation, the lighting class and whether the new lighting is brighter than the old. The Wuppertal example shows this: the illuminance rose significantly there, and the saving is at the lower end. For funding under the Kommunalrichtlinie, at least 50% greenhouse gas savings must be demonstrated.

Many old installations only know on and off. The City of Wermelskirchen reports that its old installation often ran unnecessarily at full load. Now 75 lx is enough for training, and full power is enabled for evening training and floodlit matches. In Wuppertal too, dimming to training level brings additional savings.

The association guide also recommends switching and dimming in sections, for example only one half of the pitch or a third of the pitch. For funded installations, the Kommunalrichtlinie requires control suited to use, for example two-stage for training and competition.

Scenes enter the calculation like this: for each scene, apply the actual power and the hours per year and add up the results. Our STL963 and STL1443 floodlights can be dimmed via 0⁠–⁠10 V, optionally by potentiometer, remote control or internet. With the control, you call up scenes such as training or match via app.

Include maintenance too. The association guide mentions materials and installation for lamp replacement, because cherry pickers are needed for that.