If you want a better looking installation, more comfortable working conditions and a change from boring flat panels, then a suspended direct/indirect luminaire is the answer. They are sometimes called bi-directional luminaires.
What’s bad about recessed flat panels is that you inevitably have a dark ceiling because no light is shining on it. This tends to make the space look gloomy even if there is a high level of illumination on the desk top.
A well-lit ceiling improves the look of the workspace immensely and you don’t necessarily have to compromise on the efficiency.
Neither is a high ceiling necessary for direct/indirect luminaires. They can work perfectly well with a standard 2.4m from floor to ceiling, although some luminaires will work better at 3m, or more.
To achieve the best visual effect, the upward light needs to have a fairly wide angle, greater than 90°, for example. This should prevent any chance of having a hot spot on the ceiling just above the luminaire.
Similarly, to make the ceiling look bright, you do need have a decent proportion of the light output to be emitted upwards. Technically, this is known as the ULOR, Upward Light Output Ratio. A value of 5 per cent won’t be enough to lighten the ceiling. It’s impossible to be precise but look for a ULOR of 20%, or more. Many manufacturers offer a choice of ULOR so you can choose the balance of how much upward and downward light there is.
Usually, there is a choice of optics to meet the luminance/brightness limits of 1,500 cd/m2 or 3,000 cd/m2 recommended in EN 12464-1.
Many of these luminaires are designed to be mounted in continuous rows or used to form shapes such as rectangles. As such, a lot of luminaire design effort has been put in to ensuring that the finished installation has straight lines which are easy to make level. Check how quick it is to install and look for aspects such as how the ends join, whether there are visible gaps, light leakage and how the suspension wires can be adjusted for height.
A useful feature is being able to control the amount of upward and downward light separately. Being able to change the colour temperature is also a nice addition.
All the luminaires reviewed here are good quality products and worth considering. Differences in star rating are mainly due to a particular aspect of the luminaire rather than an overall judgement.
The samples reviewed were single, stand-alone, suspended mount units rather than continuous rows.
Similarly, the price range is for 50 No suspended, 1,200 mm or 1,500 mm, stand-alone units, complete. The trade price ranges are: £(<£150/€185/$215), ££(£150/€185/$215 to £300/€370/$425) and £££(£300/€370/$425 to £450/€560/$640).
This is a really solid luminaire of anodised aluminium. All the joins are straight. The diffuser is flush with no gaps at the edges.
The stand-alone unit is 1,500 mm and you can have continuous mounting in lengths which are multiples of 500 mm. A nice feature is that the suspension points are moveable and can be almost anywhere along the length of the luminaire.
The downward light has two options, either an opal diffuser or a micro-prismatic lens which limits the luminance to < 3,000 cd/m2. The upward light is emitted through a 500 mm long opal diffuser midway along the luminaire.
There is a good balance of 58 per cent emitted downwards at 60° cut-off and 42 per cent upwards over a total 120°.
- Price range ££
The Kachina has been thoughtfully designed for ease of installation and for constructing long runs. The luminaires can be centred at exactly 3,000 mm to match the building gridlines and the subdivision of floor plates. The benefit is to greatly reduce the need for special cut lengths.
The body is made of steel and aluminium and the stand-alone version is available in 1,200 mm and 1,500 mm lengths.
The appearance of the luminaire is different from many in that the wide body has a central, micro-prismatic panel which emits about 85% of the light downwards. The LEDs are mounted in the edge of the body rather than directly above the panel, so the appearance is much more uniform than some others.
The 15 per cent upward light is emitted from small reeded panels. Personally, I would like to see a bit more upwards especially since the highest wattage version emits over 7,000 lm so there’s plenty to spare.
- Price £
Fagerhult Itza Beta Opti
This is a really nice fitting in all sorts of ways. Straightaway, it sets itself apart because the shape is different, being triangular with a square section on top. The end caps come in a range of different colours so you could differentiate areas in a large open plan office.
Over half (52 per cent) the light is emitted upwards and this has a batwing distribution so the beam is nice and wide and you don’t get a hot spot on the ceiling.
Facing down, the Beta Opti has a double parabolic, satin aluminium reflector suitable for VDU use. Another feature I like about this is that there is a frosted cover over the LEDs. Even if you look directly into the luminaire, there is no glare. Many louvered or lensed luminaires have bare LEDs (or T5 lamps) which can be painfully intense if you look straight at them.
One final aspect is their e-Sense control. It is primarily aimed at cellular offices, workstations and meeting rooms where you want individual control. It is the first time I have actually wanted to use an app on my phone to control a luminaire and that’s because it is just so easy to use.
- Price ££
Glamox Luxo Reed LED
This is a solidly constructed, all-aluminium luminaire. Like many others, its background comes from a family of efficient T5 luminaires.
The standard downward facing lens is micro-prismatic. The upper lens is slightly frosted acrylic. Where the Reed is different from many other products is that Glamox Luxo offer three different combinations of upward and downward light: 50 per cent up/50 per cent down, 40 per cent up/60 per cent down and 0 per cent up/100 per cent down. This means you can suit the light distribution to the task and visual environment.
The T5 version of the Reed has different optical distribution options. Tunable white from 3,000K to 6,000K is also available.
Standard lengths are 1200 mm and 1500 mm and there are small brackets for flexible angles.
- Price £
iGuzzini Lightshine MJ24
Taste is personal but I defy anyone to say this isn’t gorgeous. It’s a wafer thin oval, 31mm high, anodised aluminium profile with gun metal grey end-caps. The reflector optics are recessed in a high gloss black slot.
Approximately 45 per cent of the light is emitted upwards in a 120° beam through a reeded lens. The downward light is projected in a 60° beam from three modules. The module is the tried and tested, low glare, LaserBlade optic. Each contains five LEDs with a narrow beam reflector and has a CRI of 90.
That said, Lightshine is available in one length only and the efficiency isn’t as high as some of the other luminaires in this review.
As well as this version, a second option has a much wider light distribution both up and down and is fitted with acrylic and polycarbonate diffusers.
- Price ££
Schmitz S 55 series
This was launched at the Frankfurt Light + Build exhibition in 2016. It is a beautifully finished, slim luminaire which can be used stand alone or in multiples of 140 mm from 840 mm long to 2.8m.
Like some others, the suspension points can be anywhere along the length.
As supplied, the luminaire is all of a piece. There is no obvious “kit of parts” to show how it has been assembled. All the joins are very slim and even. The light is flashed evenly across the diffuser and there is no light spill from the end caps.
The light distribution is 57 per cent direct and 43 per cent indirect when using the opal cover. A micro-prism version is also available where you need some glare control. You can also have two separate drivers to control the upward and downward light individually.
- Price £££
This is the slimmest luminaire I have ever reviewed, being just 16mm thick. It also looks a lot different from the others reviewed here. It uses a clever technique whereby LEDs integrated into the frame of the luminaire direct the light into an etched pattern on an acrylic sheet. This then glows and emits light up and down. This optic is especially clever because it uses two sheets to give a different light distribution up and down.
The downward light has a cut-off of about 60°. The upward component is unusual in that it has a “trouser leg” distribution. I.e. two narrow beams directed at about 30° above the horizontal. This gives great uniform illumination on the ceiling even on a short suspension.
The combination gives a very wide indirect component with VDU compliance to EN 12464.
- Price £££
Wila Linic NX
This builds on the existing Linic family of luminaires with the NX signifying that it has an indirect component. The range can be fully recessed, surface mount or suspended so you can have lines of light no matter how the architecture of the ceiling changes.
Related to this is that the Linic is available in almost any length down to a precision of 2mm – you aren’t limited to standard lengths. Their website has a layout configurator which, in effect, produces a parts list of everything you need.
There are three options for the downward beam. The mini reflectors are designed for VDU workstations where you need the lowest luminaire luminance. The micro-prismatic lens is suited to laptops and meeting rooms where there is no fixed work position. An opal lens gives a total homogeneous line of light and is used in foyers, corridors, public spaces etc.
Upward light is emitted through an opal lens emitting 2,000 lm per linear metre with a beam angle of approximately 120°.
- Price ££
This is control heaven. A Sequence luminaire has four DALI addresses, three for the downward light and one for the upward. The three DALI addresses refer to the left, centre and right groups of modules.
The standard length of a Sequence is 2.1m and this contains 14 LED modules. You can also have a 1.2m long version with eight modules.
The addresses mean that the Sequence can have different light output along its length. This is useful where you want a different illumination on an adjacent desk. You can also use it to exploit EN 12464 in an open plan office by having a high illumination on the tasks but a lower level on the “routes” between the desks.
Since the proportion of upward (10 per cent to 25 per cent) and downward light can be individually controlled. The appearance of the space and the light on the task can be almost infinitely controlled.
An attractive feature is that the square lensed LED modules have a surround of a frosted diffuser. This makes the otherwise high-tech luminaire have a “softer” appearance.
Control is via the LITECOM software which is pre-installed in the luminaire. You can then set up the layout and scenes via any web based link.
- Price Price on Application
See innovations from Light+Building and more at next month’s LuxLive Middle East at the Abu Dhabi National Exhibition Centre. Big-brand exhibitors include Erco, Fagerhult, Linea Light, Lumenpulse, Opple, Regent, Forma, Ruud, Schreder, Coelux, Soraa, Tridonic, Trilux and many more. It takes place on Wednesday 13 April and Thursday 14 April 2016 and entry is free if you pre-register at www.luxlive.ae