There is no doubt that continuous lines of light across a ceiling can be a very attractive way of lighting a space. Architects and interior designers love them. Continuous lines can help break up a large area such as an open plan office. Instead of a Morse code row of linear luminaires, a continuous line looks and performs much better.
Continuous lines can also highlight a stepped ceiling such as an auditorium. Recessed in walls, they can give an impression of depth and interest to a corridor or they can outline architectural features such as alcoves.
Of course, the devil is in the detail and a lot of work goes in to the design of these luminaires. For example, if the ceiling is 30m long, how do you join the luminaires together both physically and optically so that they appear to be one piece? Related to that is how do you make sure no light escapes from the joins? Producing standard length luminaire bodies which are multiples of 500 mm and 600 mm will fit most UK ceilings. A lot of manufacturers can supply even shorter lengths.
Optically, there is not much choice because the luminaires tend to be quite narrow and hence opal or micro-prismatic diffusers are usually the only options. Glare is not normally a problem but check the UGR if you are using a high output version luminaire in the narrowest width version.
Although most manufacturers offer these luminaires in suspended, surface mount and recessed, we have concentrated on the recessed versions.
This has two rows of LEDs behind the 60 mm wide body. The LEDs themselves are protected by a continuous clear lens, which means they are easy to clean. Unfortunately, in operation, the LEDs are clearly visible with either the opal or prismatic lens. The latter produces interesting circular and elliptical shapes on the prisms. The lenses are easy to fit and with careful manipulation the join can be made almost invisible.
The body is made from 600mm modules which can be linked (electrically and mechanically) quite easily, so installation shouldn’t be a problem. Custom lengths are also available.
The mechanical join is only on the upper surface, not on the sides. On our sample, this meant that some light escaped along the vertical sides. It’s a nicely made luminaire but it needs something to give extra rigidity on long, continuous runs.
LED Linear Xoominaire 9999
This is a slightly larger luminaire than many, being 99mm x 99mm in section. It is designed as a surface or pendant mount unit and is available in three lengths, 1412mm, 2821mm and a super long 4230mm, the latter presumably by joining the two shorter lengths together. Custom lengths are also available.
There are ten different optical distributions. The sample we received had the opal wide diffuser with collimator. Whilst this produced a dot-free appearance, you could still discern the line of LEDs.
This sample was a demo unit comprising three body sections of black, white and silver. Although it had a good paint finish, unfortunately, light escaped from both the joins in the body and the diffuser.
Optelma Flute 60
We chose the Flute because of its unusual flared wing' and endcaps. This recessed unit is a made to measure, M2M, luminaire that can be built to almost any length.
The opal polycarbonate diffuser is 60mm wide and the curved, flared walls and end caps produce an attractive gradation of light across the matt white surface. Wall-wash and micro-prismatic optics are also available.
The construction is interesting in that the LED board is located in position by magnets. The result is that, together with a clip-in diffuser, the whole luminaire is quick to install. The diffuser is supplied on a 3m roll so there would be very few visible interruptions to the line of light.
Altogether, a bit more thought and design has gone in to this luminaire than many of its competitors.
This is stylistically very good. The sections bolt together tightly and this means there is no light loss through the sides. Similarly, the opal diffuser fits very snugly and the ends butt together so the join is almost invisible.
Best of all, the LEDs are set well away from the 60mm wide diffuser, so the appearance is totally uniform. The LEDs extend right to the ends so there are no dark areas between the sections.
Like some other manufacturers, there is a clear cover over the LEDs so that cleaning is simple. The body sections are easy to join internally, both electrically and mechanically. Again, the diffuser and LED gear tray are easy to install.
Viabizzuno 13 x 8
This is amazingly small. 13 x 8 refers to its dimensions in millimetres. You read that correctly, the complete luminaire is 8mm wide.
It isn’t much bigger than a pencil except that it is 2.1m long and joins aren’t noticeable on longer lines.
Equally remarkable is that the appearance is totally uniform. The diffuser is opal polycarbonate and emits a lot of light. 3,000K is the standard CCT and this suits typical applications.
This product is not for large areas, but for where you want the finest of lines to delineate an edge.
Zumtobel Slotlight Infinity
This is all you would expect from a luminaire designed by Arup and built by Zumtobel. You can buy a single piece luminaire up to 4m long. They have cleverly overcome the problem of joins in the diffuser by supplying it on a roll, which can be cut to length on site.
A standard roll is 20m long, which is enough for most applications although they recently installed a continuous 29m diffuser.
Switched on, the diffuser is totally uniformly lit. The Slotlight Infinity also has standard corner pieces with a one piece diffuser so there is no visible mitre joint.
You won’t be surprised to learn that its method of fixing allows for thermal expansion and undulations in the ceiling. It also deliberately produces a very fine, wafer thin, shadow gap.
Like some other manufacturers, the LEDs are covered to prevent damage to the board and for easy cleaning. There are three optics available; one with a UGR of <22, another <19 UGR and a wall wash. All have an opal appearance.