The Society of Light and Lighting FACTFILE NO. 2 May 1996 Car Park Lighting Dilemma Solved Since the publication of BS 5489 Part 9 in 1992 and the CIBSE Guide LG6 The Outdoor Environment in 1986 there has been considerable confusion over illuminance levels for car park lighting design. During the Summer of 1996 there will appear a new version of BS 5489 Part 9, that has been agreed by CIBSE, BSI, ILE, BPA, ACPO and CAA. This new Part 9 takes into account 3 years work by a BS working group who visited 90 multi-storey car parks and 30 surface car parks across the UK. The working group started with 19 members; this was too large for agreement, but was useful at first for all opinions to be aired. The major difference between the CIBSE and BS recommendations was for the multi-storey car park, so this was tackled first. Multi-storey Car Parks The first meeting assembled in Birmingham City Centre to visit 10 car parks. The survey group included only one woman, but this did allow some discussion of the issues regarding the feelings of women using multi-storey car parks. These first surveys provided a good basis for making a recommendation, but because there had been such controversy it was decided that further surveys should be carried out both at night and during the day. These further surveys showed that there is more to lighting a car park than simply specifying horizontal illuminance. The car park judged to have the best lighting was perceived to have an illuminance of 200-300 lux but the measured value was only 100 lux. This example provided a high degree of uniformity (more than 0.8) for both horizontal illuminance at floor level and vertical illuminance at 1.5m. The ceiling, floor and walls all had very light finishes so the overall effect was a bright appearance with no dark corners and where faces could be recognised at distances up to 60m. Even late at night this car park was well used although another park across the road was almost empty, demonstrating how effective lighting can attract customers and produce direct commercial benefits. In drafting the new Standard, uniformity and the associated feeling of security were incorporated, as well as the use of light coloured surfaces. Reflection factors for walls and ceiling should be not less than 0.5. In the interest of energy conservation it was decided to specify the lowest lighting level commensurate with the highest uniformity of 0.7 considered obtainable by the use of commercially available luminaires. However, not all car parks are of open construction or designed with, or can accommodate light surfaces, but as uniformity is key, the minimum uniformity required is 0.4. Table A below indicates the minimum requirements for the lowest uniformity of 0.4. Note that it will be necessary to increase the average illuminance when the uniformity is less than 0.67 for the parking bays, and less than 0.5 for the ramps and pedestrian areas.

TABLE A. Recommended levels of lighting for multi-storey and underground car parks Area E(average) E(minimum) lux lux Parking bays, access lanes 75 50 Ramps, corners, intersections 150 75 Entrance/exit zones (vehicular) 75 night n/a 300 day Pedestrian areas, stairs, lifts 100 50 E(average) is the maintained horizontal illurninance at floor level. E(minimum) is the maintained minimum horizontal illuminance at floor level at any point within the calculation grid, which should be no more than 0.5m from the wall or perimeter of the area. Uniformity is the ratio of E(min) to E(ave) Exterior Car Parks For lighting purposes outdoor car parks can be regarded either as surface car parks or the open roof level of multistorey car parks. The difference between CIBSE LG6 and BS 5489 is not as wide as for interior lighting but it was considered wise to check the previous recommendations. Vertical illuminance is again important to reduce the fear of crime and to see facial expressions easily. The minimum uniformity ratio for exterior car parks is 0.2. This is generally easy to achieve with floodlighting but obtrusive lighting must be taken into account. The Guidance Notes for the Reduction of Light Pollution issued by the ILE were adopted. These guidance notes classify Environmental Zones which equate to the district brightness of the surroundings and hence the desirable lighting level. E1 National Parks, areas of outstanding beauty, other dark landscapes E2 Areas of low district brightness (e.g. rural location) E3 Areas of medium district brightness (e.g. urban location) E4 Areas of high district brightness (e.g. urban centre with high night time activity) For each zone there are limitations for sky glow (direct upward light), light into windows, source intensity (beyond illuminated area), and building luminance. TABLE B. Recommended levels of lighting for outdoor car parks and multi-storey roof level Area E(average) E(minimum) lux lux Rural, Zones E1 and E2 15 5 Urban, Zones E3 and E4 30 10 Multi-storey roof level* 30 10 E(average) is the maintained horizontal illuminance at floor level. E(minimum) is the maintained minimum horizontal illuminance at floor level at any point within the calculation grid, which should be no more than 1 .0m from the wall or perimeter of the area.

Uniformity is the ratio of E(min) to E(ave) In a similar manner to the interior lighting when the minimum uniformity is less than 0.33 the average illuminance will need to be increased accordingly. *For obtrusive light control the multi-storey roof level should be considered as in Environmental Zone E1. Conclusion These recommendations will be included in the new edition of BS 5489 Part 9 to be issued later this year and when available this document should be considered as replacing the recommendations in CIBSE LG6. The Secured Car Parks scheme operated by the Automobile Association has also been revised as a result of these recommendations. References 1 BS 5489 Road lighting, Part 9 Code of Practice for lighting urban areas and public amenity

areas, 1996 2 CIBSE Lighting Guide The Outdoor Environment, LG6: 1992 3 Institution of Lighting Engineers Revised Guidance Notes for the Reduction of Light

Pollution, 1994 Note (January 2006) This document has been superseded by guidance in European Standards but may be useful when the recommendations in those standards are inappropriate. In particular, the Society recommends that for outdoor ca rparks the recommendations here be followed rather than those in the draft EN 12464-2.