The AX Series is specified like any other luminaire — same ceiling grid, same driver, same commissioning. Its output is negative. A space can be taken down by four hundred lux without touching a single fitting that is already in it.
Maintained illuminance in retail, transport and workplace interiors has risen in every decade on record and has come down in none of them. Nobody decided this. It is the sum of a great many individually reasonable decisions, each of which added a fitting.
The complaints a facilities manager receives are no longer about seeing. They are about screens, about headaches from three o'clock, about staff who take their breaks in the car park because it is the only place on site that is restful, and about customers who move through a space quickly without being able to say why.
Dimming does not solve this. Dimming is a budget line somebody has to defend at the next review, and it is the first thing reversed when a store underperforms. Removing fittings does not solve it either: the fittings are rarely the client's to remove, the ceiling is rarely the client's to open, and some luminaires on the market do not have an off state at all — the switch selects between on and waiting.
Subtractive lighting is specified alongside what is already there. Nothing is taken out, nothing is turned down, and nobody has to explain a reduction to anybody. The lux level simply falls.
All four are specified from the same schedule as emissive luminaires and install on the same centres. Output is quoted at 4000 K equivalent for comparison, although the figure has no colour.
Power consumption is real and positive. An AX fitting draws current in the ordinary way. This is the single most common question we are asked and the answer disappoints people.
Independent goniophotometry, annually. We publish the full distribution and the uncomfortable parts of it.
| Distance from axis | Illuminance |
|---|---|
| 0.0 m (nadir) | −214 lx |
| 0.5 m | −181 lx |
| 1.0 m | −108 lx |
| 1.5 m | −52 lx |
| 2.0 m | −19 lx |
| 3.0 m | −4 lx |
| 4.0 m | 0 lx |
Unified Glare Rating is defined by the standard over the range 10 to 30. The AX Series returns values below 10 in all four fittings and below zero in two of them. There is no provision in the standard for a negative UGR and no guidance on what one means. We report the measured figure.
Falloff is cubic rather than square and reaches zero, not an asymptote. At four metres from axis an AX fitting is not doing anything at all, which makes layout unusually forgiving and makes a partial installation very visible.
Lower level, 11,200 m². Maintained illuminance 180 lx before, 25 lx after. The existing luminaires were not altered, rewired, dimmed or switched off, and the client's energy consumption rose slightly.
The reference fitting. The other three differ in aperture, output and ingress rating and in nothing else.
| Aperture | 200 mm |
| Cut-out | 185 mm |
| Recess depth | 142 mm |
| Rated output | −640 lm |
| Beam | 60° |
| Input power | 19 W |
| Efficacy | −33.7 lm/W |
| Ingress | IP44 |
| Control | DALI-2, 1–10 V |
| Rated life, L70 | 60,000 h |
| Colour temperature | Not applicable |
| Colour rendering | Not applicable |
| Emergency variant | Not offered |
| Guarantee | 7 years |
There is no emergency variant and there will not be one. An AX fitting on a maintained emergency circuit would subtract during an evacuation, and no reading of the regulations we have been able to obtain permits this.
Figures are maintained illuminance at working plane, taken by the client's own consultant, at night, at handover.
| Sector | Area | Before | After | Fittings |
|---|---|---|---|---|
| Supermarket, two stores | 4,100 m² | 860 lx | 410 lx | 62 |
| Transport concourse | 9,800 m² | 540 lx | 190 lx | 148 |
| Office, three floors | 2,600 m² | 620 lx | 300 lx | 44 |
| Car park, two levels | 11,200 m² | 180 lx | 25 lx | 96 |
| Teaching hospital, one wing | 3,400 m² | 490 lx | 240 lx | 71 |
| Private residential campus | — | — | — | 1,240 |
The campus installation is ongoing and figures are not released. It is the largest subtractive scheme in existence by a factor of about nine.
Every scheme begins with a night visit and a meter. Bring the complaints log rather than the lighting layout; it is a better brief and it is usually the only honest document on the project.
[email protected]Test room and goniophotometer · VGRIZ campus, Sector 4 · visits are at night