Astronomy is back as a Saudi tourism asset, and that means outdoor lighting in NEOM, AlUla, the Red Sea Project all now spec to International Dark-Sky Association (IDA) standards. Lower CCT, full shielding, smart curfews. Here is the new outdoor language.
Four ideas to carry into the next specification conversation you have.
Light emitted above the horizontal. IDA-compliant fixtures: ULOR = 0%. EU policy default: ULOR < 3%.
Below 3000 K CCT (often 2200–2700 K). Blue light scatters more in the atmosphere, brightening the sky.
Cut-off classification (IES TM-15) defines BUG ratings: Backlight, Uplight, Glare. Spec B1 U0 G1 or tighter for IDA-compliant.
Reduce output 50% after midnight, off in remote zones. Trinkets like NEMA 7-pin sockets and ANSI C137 dimming make this possible without rewiring.
Per IDA Fixture Seal of Approval and IES TM-15 (BUG rating system).
| Parameter | Dark-Sky limit | Reference |
|---|---|---|
| CCT | ≤ 3000 K (≤ 2200 K preferred) | IDA · IES TM-15 |
| ULOR (uplight) | 0% (U0 rating) | IES TM-15 |
| BUG rating | B1 U0 G1 or better | IES TM-15 |
| Spectral G-index | ≥ 1.5 (warm) | IDA Pro guide |
| Backlight (B-rating) | B0–B2 maximum | IES TM-15 |
| Mounting tilt | 0° (flat horizontal) | IDA Fixture Seal |
| Adaptive control | Dim 50% post-midnight | NEMA 7-pin · C137.1 |
| Light trespass | < 0.1 lux at property line | IES RP-33 |
Five reasons the standard moved from niche to mainstream after 2020.
AlUla's tourism programme markets star-gazing as a heritage experience; NEOM's masterplan includes 'low-light' zones as a luxury amenity. Both projects mandate IDA-compliant outdoor lighting in their RFP language. A bright streetlight is now a deduction.
Sky brightness from a city scales with the blue-light content of its outdoor sources. Switching from 4000 K to 2700 K LED cuts the photopic-to-melanopic ratio by roughly half, reducing sky glow without changing perceived ground brightness.
Older IES TM-15 (pre-2011) used categories like 'full cut-off' and 'semi cut-off.' Modern TM-15 splits the assessment into Backlight (light onto adjacent properties), Uplight (sky glow), and Glare (toward observers). Each gets a number 0–5. Lower is better. Spec the BUG, not the legacy term.
NEMA 7-pin photocell sockets on streetlights accept dimming controllers (Itron, Echelon, Telensa, Schréder). Operators can dim 50% post-midnight or trigger off on remote roads, without rewiring. Saudi municipalities (Riyadh ROYA) are tendering smart streetlight programmes now.
Sodium streetlights produced 2100 K orange and 5 lm/W in dark-sky terms. Modern 2700 K "warm-white" LEDs at IDA-compliant U0 deliver more ground lux at less sky glow than the HPS they replaced. The Dark Sky case actually drives LED adoption, not against it.
Our outdoor catalogue includes IDA-compliant streetlight families at 2200 K and 2700 K, U0 uplight, with NEMA 7-pin adaptive control built in.
Practical lighting know-how from NLC Academy. No spam, unsubscribe anytime.
By subscribing you agree to receive NLC emails.