Before LEDs dominated specifications, four light sources ruled. Each had a job. LED replaced most, but not all. Knowing what came before makes you read modern spec sheets sharper.
Four ideas to carry into the next specification conversation you have.
Filament in halogen gas. Beautiful colour. 17 lm/W efficacy and 2,000 h life killed it. Still used in optics labs and select hospitality.
Gas discharge through phosphor coating. 80–100 lm/W. Banned in Saudi Arabia since 2021 under Minamata convention. Recycle responsibly.
Metal halide and high-pressure sodium ruled streets and stadiums. 100–150 lm/W. Lost to LED on warm-up, dimming, and life.
LED hasn't replaced germicidal UV-C, deep-IR sensing, or ultra-high CRI broadcast tungsten. Pre-LED tech still ships.
Approximate values for late-generation pre-LED products vs. modern LED equivalents.
| Source | Typical efficacy · life | LED replacement |
|---|---|---|
| Incandescent (60 W bulb) | 13 lm/W · 1,000 h | LED 100 lm/W · 25,000 h |
| Halogen MR16 | 17 lm/W · 2,000 h | LED MR16 80 lm/W · 30,000 h |
| Compact fluorescent (CFL) | 60 lm/W · 8,000 h | LED 100 lm/W · 25,000 h |
| Linear fluorescent T8 | 90 lm/W · 20,000 h | LED T8 retrofit 130 lm/W · 50,000 h |
| Mercury vapour HID | 50 lm/W · 24,000 h | LED highbay 150 lm/W · 80,000 h |
| Metal halide HID | 90 lm/W · 15,000 h | LED 150 lm/W · 80,000 h |
| High-pressure sodium | 120 lm/W (orange) · 24,000 h | LED streetlight 160 lm/W · 100,000 h |
| Low-pressure sodium | 180 lm/W (monochrome) · 18,000 h | LED + amber filter for dark-sky |
Five points that help you read retrofit jobs correctly.
A halogen lamp shifts towards warmer (2200 K) as it dims, like a real candle. Most LEDs hold their CCT or shift slightly cooler. Premium hospitality and theatres specify "warm-dim" LEDs (2700 K → 2000 K dimming) to mimic halogen behaviour.
Replacing a T8 tube with an LED T8 retrofit means deciding: keep the magnetic ballast (Type A), bypass it (Type B), or replace with external driver (Type C). Each has fire, warranty, and electrician-cost consequences. Read the fixture spec sheet before quoting.
A metal-halide stadium light needs 5 minutes to reach full output and 10 minutes to re-strike after a brief power loss. Stadiums kept HID late because dark periods during play are not tolerable. LED replaced HID only once instant re-strike was solved.
Saudi Arabia ratified the Minamata Convention in 2018; mercury-bearing CFLs and linear fluorescents have phased out of new builds. Retrofit projects must include hazardous waste handling and certificate of disposal. Plan and budget for it.
Astronomy domes still use sodium-spectrum lighting because its narrow yellow band can be filtered out of telescope data. Reptile husbandry uses true UV-A/UV-B fluorescent for skin synthesis. "Just put LED" is not always the right answer.
From halogen wall-wash to HID highbay to T8 retrofit, we audit existing installations and recommend the LED equivalent that matches lux, colour, and dim behaviour.
Practical lighting know-how from NLC Academy. No spam, unsubscribe anytime.
By subscribing you agree to receive NLC emails.