Glare and spill: keeping sports light where it belongs

Two complaints follow badly designed sports lighting: players who cannot see the ball, and neighbours who cannot sleep. Both come from the same thing — light going where it should not.

Glare for players

Glare is driven by the luminance of the fixture as seen from the player's eye, relative to the background. At night the background is dark, so even moderate fixtures can be uncomfortable. The main levers:

• Keep fixtures out of sight lines. No poles behind tennis baselines, no fixtures directly above basketball hoops, careful positioning at goal ends.
• Aim lower. Higher mounting lets the fixture point more steeply down, so the bright face is seen less directly.
• Shield the source. Visors and louvres cut the view of the LED array from shallow angles.

Spill and light trespass

Spill is light that falls outside the playing area — on houses, roads or habitats. Local authorities increasingly set limits for vertical illuminance at windows and for upward light.

• Asymmetric optics throw light forward while the glass stays close to horizontal. This is the biggest single improvement over a symmetric floodlight tilted up.
• Rear shields stop backward light from poles on the boundary.
• Calculation at the boundary. We add a vertical calculation grid on neighbouring façades and submit the results with the planning application.

The dimming dividend

A field lit to match level only when a match is on, and to training levels otherwise, produces far less spill over a year. Controls are a spill-reduction tool, not just an energy one.