A working taxonomy of luminaire types

Product catalogues are organised by how things are manufactured. That is the wrong order for designing. A scheme is built from what the light is doing — washing a surface, marking a threshold, pooling on a table — and the fitting is whatever delivers that with the least visual noise.

So this is organised by where the fitting sits and what it is asked to do. Learn the families and the specific product almost picks itself.

Recessed

The fitting disappears into the ceiling and only the effect is visible. The default for most architectural interiors, and the family with the most ways to go wrong.

Downlight. A fixed, symmetric distribution pointing straight down. Good for general illuminance, poor at everything else — it lights floors and tops of heads, and leaves walls dark. The most over-used fitting in the industry.

Adjustable downlight / directional spot. The same aperture with a gimbal, usually ±30–40°. This is what does the actual design work: accenting, wall grazing, picking out a texture. Specify a locking mechanism, and budget a focusing visit or the aiming will drift within a year.

Recessed wall washer. An asymmetric optic, often with a kicker reflector, made to put an even gradient down a wall from a fitting mounted close to the ceiling. A downlight aimed at a wall is not a wall washer — it produces a scallop, not a wash.

Linear recessed. Continuous runs, either lensed for general light or with a dark honeycomb for low-glare office work. Watch the joints: an interruption every 1.2 m reads as a defect, and “continuous run” must be stated in the schedule.

Trimless / plaster-in. No visible flange; the ceiling finish runs right up to the aperture. Beautiful, and unforgiving — it must be coordinated with the ceiling contractor before boards go up, and it is effectively unmaintainable if the driver is not remote.

Surface and suspended

For ceilings you cannot cut into: concrete soffits, heritage fabric, exposed services.

Surface downlight. Same optics, mounted proud. Honest and easy to maintain, but the fitting is now part of the visual composition, so its form matters.

Pendant. Hangs on a cable or rod. Two very different jobs: a decorative pendant is an object you are meant to look at, while a functional pendant (over a desk or a counter) is a light source you are meant to look past. Do not let one masquerade as the other.

Suspended linear. Direct/indirect distribution — some light down to the task, some up to bounce off the ceiling. The indirect component is what lowers UGR and stops an open-plan office feeling like a cave.

Panel. A large diffusing surface, low luminance, very cheap. Efficient and glare-free, and almost entirely without design intent. Fine for a back office; wrong for anywhere anyone is meant to feel something.

Track

Track spot. A live rail with fittings that clip anywhere along it. Unbeatable where the layout will change — galleries, showrooms, retail. The trade-off is that the fittings are always visible, so the track becomes a design element whether you want it to or not.

Magnetic / low-voltage track. A recessed channel carrying 48 V, into which spots, linear modules and pendants all clip. Currently the most flexible interior system available, and the detail to reach for when a client says the layout may change.

Concealed and integrated

The source is never seen; a surface becomes the apparent luminaire. This is where lighting stops being a product and becomes architecture, and it lives or dies on the detail drawing.

Cove. Light hidden in a recess, thrown up onto the ceiling or down a wall. The depth of the cove and the setback from the lip decide whether you get a smooth gradient or a hot line.

Tape / strip. Flexible LED on a reel, cut to length. Ask about binning across reels, the drive current, and how the aluminium profile sheds heat — tape run hot in a sealed channel fails early and unevenly.

Handrail and step light. Low-level, low-output, marking a level change. Aim below eye height and check the luminance from a descending viewpoint, which is where they most often dazzle.

Exterior

Bollard. A short post lighting a path from about a metre up. Choose the ones that emit downward only — a bollard with a glowing head is a glare source at eye level for a seated person and contributes nothing useful to the ground.

Floodlight. Wide-beam, high-output, aimed at a surface from a distance. The family most likely to cause obtrusive light complaints; specify glare shields at concept, not after.

Inground uplight. Recessed into paving, aimed up at a tree or a façade. Beautiful and maintenance-hungry: it fills with water, gets walked on, and is the single most common exterior failure. Insist on a drainage detail and an IP67 minimum, and never place one where someone will stand on it and look down.

Pole-top and street. Roadway and car-park lighting, usually full cut-off by regulation.

Façade grazer / linear exterior. Close-offset linear fittings that rake a façade. The exterior counterpart of interior grazing, and the same rule applies: it reveals every imperfection in the substrate.

Underwater. Pools and water features. A separate discipline — low voltage, bonded, and with material compatibility to chlorine or salt that must be confirmed in writing.

Industrial

High bay / low bay. Wide, efficient distributions for warehouses and factories, chosen by mounting height. Above about 8 m you are in high bay territory.

Batten. A bare linear fitting, often IP65, for plant rooms, car parks and back of house. Cheap, robust, no pretension.

Choosing between them

Four questions settle most decisions.

What surface am I lighting? Floor, wall, object or face. A wall wants a washer or a grazer, an object wants an adjustable spot, a face wants something with a vertical and diffuse component. Getting this wrong is why so many rooms are lit and still look bad.

Will the fitting be seen? If yes, its form is part of the architecture and needs the architect’s agreement. If no, spend the money on cut-off and optics rather than on the housing.

Who reaches it in three years? A trimless fitting at 6 m over a stairwell will not be maintained. That is a design decision, not a facilities problem, and it belongs in the concept conversation.

What is the ceiling actually made of? Void depth, plenum services, structural slab, acoustic board. This kills more fitting selections than any other single factor, and it is the reason to have the conversation at concept rather than at tender.

A note for projects in Vietnam

Two constraints bite harder here than the European catalogues assume.

Humidity and ingress. Sealed exterior fittings that cannot breathe accumulate condensation internally in a tropical climate. For covered exterior positions an IP65 fitting with a breathable membrane often outlasts an IP68 one.

Lightning. Vietnam has a high lightning density and 2 kV surge protection is not enough on an exterior circuit. Specify 10 kV, on every exterior run, in the schedule. It is the most common cause of losing a whole façade installation in one storm, and the cost at tender is trivial next to a replacement.