Cities are becoming ever more busy and congested and in response attractive spaces are needed where people can find peace and quiet. At night city squares and courtyards need to be safe havens and places where people can gather after dark. In our latest Design Clinic, Lux's technical editor considers the best ways to light an urban courtyard.
The courtyard in question has the dimensions of a small building (12m x 25m) and the developer has introduced some welcome planting and seating in what would be an otherwise rather plain space.
In these city areas, you are often constrained in where you can locate the luminaires by all the various services under the ground, such as electricity, gas, telecoms and drainage. One of our solutions overcomes this constraint by simply placing all the luminaires and electrical supplies above ground.
If this is your first time designing the lighting for a public space, you will find that there is plenty of guidance available. For the basic functional lighting, you should refer to BS 5489 2013 or EN 13201. Both the Society of Light and Lighting guide, LG06, and the ILP have excellent documents showing ways of improving the appearance of a public space whilst meeting the regulatory constraints. There is no reason why 'functional' lighting shouldn’t also look good. After all, they aren’t mutually exclusive concepts; you can achieve both.
Never forget that vertical illumination on people’s faces is as important as the horizontal, at ground level. It is always a good idea to run a quick calculation showing vertical illumination at about 1.5m above ground.
Always consider maintenance. There is no point in having LEDs or long-life lamps if the luminaires are easily vandalised and have to be replaced.
Finally, always think about what the courtyard will look like by day as well as night. It will be seen a lot more by day than by night.
This is the most visually striking of the three schemes. It uses medium distribution FLC100 projectors mounted on three columns although, in two of the locations, they could be wall mounted.
The spotlights highlight the central seating area and staircase. The seating area is further enhanced by using ETV linear units under the benches. This is a useful technique for producing pools of light. The theme is continued with ETC uplights around the granite spheres.
Where you want linear inground lighting, the recently launched ETV has the option of five different beam distributions and this has been used to light the central sculpture.
Tech Spec A
Luminaires: FLC100 projectors, ETV100 linear inground uplights and ETC100 inground uplights
Optical control: Various
Arrangement: Pole mounted FLC100 projectors
Average horizontal illuminance: 20 lux
Wattage per luminaire: 12W FLC
Pros: Contrast and colour
Cons: More luminaires than the other solutions.
This solution is unique in that there are no columns or luminaires at ground level. Catenary lighting is where one or more luminaires are suspended from a horizontal cable. Along main roads, the cables are attached to columns but in city centres, the cables are attached to the buildings. It is a popular solution in many European countries, but less in the UK.
Here, the RFS500 series luminaires are suspended across the courtyard at a height of approximately 5m. This has the advantage of lighting the tree foliage from above and giving a wide spread of light. Many city and public authorities will not only specify the illumination level for public space but also the uniformity and minimum lux level. The wide angle beam of the RFS500 ensures good uniformity and, due to the flat glass, there is no upward light emitted.
Tech Spec B
Luminaires: RFS530 LED
Optical control: PMMA lenses and non-reflecting safety glass
Arrangement: Total of six on three suspension cables
Average horizontal illuminance: 30 lux
Wattage per luminaire: 27W
Pros: Uncluttered and nothing below ground
Cons: Requires cables to be attached to buildings
Lighting columns are making a comeback. This is because the columns can also contain WiFi hotspots, USB charge points as well as many other functions. They will be an integral part of any smart city application.
The CFT530 has a slim light emitting ring at the top which is less than 60mm deep thus producing almost a halo effect. The optics give a wide radial beam with the peak intensity at about 65° so there are good levels of illumination on people’s faces. The CFT can also be fitted with a wireless control node for lighting management systems.
This apparently ordinary scheme has a strong but simple aesthetic that grows on you the more you look.
In order to add extra interest to the scheme, we have used some colour on the sculpture using ETV linear inground units and granite spheres using ETC uplights.
Tech Spec C
Luminaires: CFT530 pole mounted luminaire and ETV100 inground uplights
Optical control: PC lens
Arrangement: Four - as shown
Average horizontal illuminance: wattage per luminaire: 27W
Pros: Simple to install and familiar in appearance
Cons: Maybe too simple for some people