When the clocks go back for winter, the car park of a commercial site falls into darkness before the end of the working day. Morning arrivals and evening departures happen under artificial light, and comments reach the facilities department within the week. Meanwhile, the installation runs at full power from start to finish, including at two in the afternoon when the level is half empty.
The subject is rarely dealt with by changing only the luminaires. It is dealt with by reworking together the level to hold, the uniformity and the operating pattern.
Covered car park and outdoor car park: two distinct logics
A covered car park is a room. It falls under the EN 12464-1 standard just like a workshop or an office, runs on artificial light from the first vehicle to the last, and imposes low mounting heights, often constrained by the beams and the services running under the slab.
An outdoor car park falls under the EN 12464-2 standard, which deals with outdoor workplaces, and under the order of 27 December 2018 on the prevention of light nuisance. This text caps the colour temperature of outdoor installations and requires the lighting of car parks serving a site or an area of activity to be switched off no later than two hours after the end of the activity.
This difference of status shows in the equipment. The covered car park calls for compact sealed luminaires that withstand washing and exhaust fumes, whereas the outdoor car park calls for optics controlled downwards and mechanical resistance to wind and corrosion.
The levels expected on parking spaces and circulation routes
The EN 12464-1 standard explicitly deals with covered car parks, with requirements deliberately modest compared with a workroom, but combined with a uniformity that cannot be neglected. The following values are maintained illuminances, measured at floor level, not values when new.
Zone of a covered car park | Maintained illuminance | Uniformity U0 |
|---|---|---|
Entry and exit ramp, daytime | 300 lux | 0.40 |
Entry and exit ramp, night-time | 75 lux | 0.40 |
Internal traffic lanes | 75 lux | 0.40 |
Parking spaces | 75 lux | 0.40 |
Pay station | 300 lux | 0.60 |
The expected colour rendering remains low in these zones, with a minimum Ra of 40, which leaves a real margin of choice. On the other hand, the uniformity of 0.40 rules out layouts spaced too widely, which show a correct average while leaving whole spaces in semi-darkness.
The access ramp and the transition between day and night
The distinction between 300 lux by day and 75 lux by night on the ramps is not a calculation convenience. It reflects the adaptation time of the eye of a driver leaving strong outdoor light to enter a dark volume, or the reverse on the way out.
In practice, the ramp and the threshold zone are handled on a separate circuit, controlled by an outdoor sensor or a timer, with a daytime level well above the rest of the level. Neglecting this point produces the well-known black hole effect at the entrance of structures, and a risk taken at the first bend.
The feeling of safety: uniformity and vertical illuminance of faces
A user does not judge a car park on an average. They judge it on their ability to identify a silhouette at a distance, to recognise a face and to see what is happening between two parked vehicles.
This ability depends on vertical illuminance far more than on horizontal illuminance at floor level. A luminaire placed above each row lights the roofs of the cars properly and leaves the aisles between vehicles in shadow, whereas a layout in line with the traffic lanes lights both the floor and the vertical faces.
The same reasoning applies to video surveillance. A camera installed in an area with low vertical illuminance produces unusable images, whatever its resolution, and reworking the lighting then costs less than replacing the cameras.
Presence detection and standby level
A car park is one of the few rooms where real occupancy collapses for long periods while still requiring immediate availability. It is the typical situation for dimming on detection.
Two points decide the result. The first is the detection technology: a passive infrared detector picks up poorly a vehicle approaching along its axis, whereas a microwave detector reacts to movement in a wider volume and works through luminaire housings.
The second is the standby level. Switching off completely creates a tunnel effect in front of the user and degrades the feeling of safety, whereas a low level kept permanently, completed by a gradual rise of the neighbouring luminaires on detection, keeps the volume continuously legible. Time delays are set on the real time it takes to cross the level, not on a factory default value. Rexylum control and safety solutions cover these dimming and detection functions.
Sealing, impact resistance and corrosion
A covered car park is washed, ventilated and used by vehicles that throw up salt-laden water for a good part of the winter. The protection rating is chosen accordingly, with at least resistance to water jets for washed areas, and particular attention to seals and cable glands, which remain the first points of failure.
Impact resistance, expressed by the IK rating, is justified in low areas and near manoeuvring corners, where mirrors and boot lids reach the luminaires. Outdoors, corrosion becomes the dominant criterion on coastal sites and on car parks treated with de-icing salt, which points to housings and fasteners suited to an aggressive atmosphere. The range of luminaires for car parks is read first on these three ratings.
Estimating the saving from dimming before ordering it
The saving from dimming on detection depends on a single piece of data: the real occupancy profile of the car park, hour by hour and day by day. A barrier, an access control system or a simple survey over a few weeks provides this data far better than an assumption made at a desk.
This data is then cross-checked with the inventory of the installed base and the floor measurements collected during an on-site lighting audit, then verified by a photometric study of the level that tests the chosen layout before ordering. It is the same approach as the one applied to the other building types presented in our lighting solutions by sector.
To have your car park surveyed and the dimming scenario suited to its real occupancy costed, request a site visit.
