Smart lighting

Smart street lighting is the closest thing to a sure bet in this atlas: swapping to LED cuts energy roughly in half, and adding remote control and dimming pushes it further. The interesting decisions are not about light. They are about who pays for the retrofit, and what else gets bolted to the pole.

The atlas holds 21 documented entries across 21 cities in 15 countries — one per city, which is itself telling: lighting is a citywide programme, not a pilot people run twice. Roughly half the entries carry a documented impact figure, the highest share of any topic in the atlas.

What the savings actually look like

Two things are worth reading out of that spread. The range 50–70% is remarkably consistent across four countries and fifteen years, which is rare in this atlas. And pilots that add presence-based dimming on top of the LED swap report the steepest per-fixture drops of all. The LED is the easy half; the control layer is where the rest of the saving lives.

The real argument for smart poles: the hole in the ground

Multi-function poles combine lighting with cameras, Wi-Fi, sensors, EV charging or 5G small cells. The feature list is the usual sales pitch. The measured benefit is duller and better.

Seoul's S-Pole programme reports roughly 23% lower average installation cost than putting the same functions on separate fixtures, alongside a before-after study finding about 14% fewer school-zone accidents at equipped sites. Shanghai's consolidation programme removed about 40,000 poles across treated streets — a 60% reduction — replacing them with 16,000 multifunctional ones carrying roughly 19,000 sets of equipment.

Neither city's case rests on the sensors being clever. It rests on not excavating the same pavement four times for four departments. That is an argument a finance director can check.

The pole is also the most visible object a city owns

Hong Kong's smart lamppost programme is the cautionary entry, and its recorded lesson is unusually blunt: deploying infrastructure capable of tracking vehicles and people, in a climate of low public trust, can turn the hardware itself into a protest target. Lampposts were physically attacked in 2019; the city replaced and functionally stripped them, and only completed the pilot after committing to remove the contested functions.

Rotterdam's Reyeroord living lab is the deliberate opposite: sensors tested in one neighbourhood, each device explained, residents involved before any wider reuse — treating public acceptance as infrastructure. Between those two entries sits every city that intends to put a camera on a lamppost.

How it gets paid for

Street lighting is the most PPP-financed genre in the atlas, because the savings are predictable enough to borrow against. Washington D.C. runs a public-private modernisation partnership; São Paulo's Ilumina SP retrofitted roughly 90% of the city's lighting under a concession; Copenhagen contracted its retrofit with a minimum efficiency target written in — which is why its saving could be checked at all.

That last detail is the transferable one. A contractual efficiency floor turns a vendor promise into an obligation, and gives the city something to verify against later.

Questions to ask before procurement

• Is there a contractual efficiency target? Copenhagen's is why its 55–57% is checkable rather than claimed.
• LED only, or LED plus controls? The second doubles the engineering and roughly doubles the saving.
• What else goes on the pole — and who decided? Cameras change the project from an energy programme into a surveillance debate.
• Can functions be removed? Hong Kong had to strip its poles; designing for reversibility is cheap beforehand.
• Who owns the poles after the concession? Twenty-year PPPs outlast the administration that signs them.
• Does dimming have a lighting-quality and safety review? Savings and perceived safety at night are a genuine trade-off, not a formality.

The practical takeaway: the energy case is proven and consistent — this is one of the few smart-city investments a city can make on the numbers alone. The risk has moved entirely to the second question: what else is attached to the pole, and whether residents were asked before it went up.