Matches in the preliminary round, round 1 or round 2 may be played in daylight or under floodlights. If played under floodlights, the illuminance must correspond to the requirements set in the UEFA Stadium Infrastructure Regulations.
From the group stage onwards, matches must be played under floodlights and the average level of horizontal illuminance must be at least 800 Eh (lux) and the uniformity ratios must be U1 > 0.40 and U2 > 0.60. The average level of vertical illuminance must be at least 350 Ev (lux). All glare ratings (RG) must be less than 50. The pitch illuminance levels should have a colour rendering (Ra) of at least 65.
From the group stage onwards, an independent backup power supply must be available and able to provide at least 350 Eh(lux) horizontal illuminance, to ensure that matches can proceed in the event of a power failure.
Clubs must ensure that floodlighting installations are maintained and provide UEFA with a valid lighting certificate issued within the previous 12 months. UEFA may conduct an independent assessment of lighting levels in stadiums and will notify the clubs in good time of the results of such assessments and of any corrections to be made.
As from the group stage, full floodlighting must be provided two hours before kick-off on matchday, or at the latest in time for the start of the GLT calibration test, if applicable, unless otherwise approved by UEFA. Clubs must provide working and/or broadcast floodlighting prior to this if requested by UEFA. Furthermore, use of LED floodlight entertainment may be permitted subject to the agreement of, and according to principles determined by UEFA. Any such lightshows must take place either before warm-up or between warm-up and players leaving the tunnel for the match. No lightshows may take place once any players (including goalkeepers) are on the field to warm up before the match, or once players leave the tunnel for the pre-match line-up.