Your lights are off. Your electricity meter is still moving.
If you run a smart home, this is worth understanding — because the standby power of smart lights can differ by more than 20× between well-designed and poorly-designed products.
A recent viral Zhihu thread asked: "Why is my meter still spinning when all the smart bulbs are off?" Hundreds of replies came in. Some users bought a power meter and discovered that 20 smart bulbs, all turned off, were still drawing 10W of standby power — about 87.6 kWh per year.
Even worse: the IEA 4E Standby Power Annex tested 12 mainstream smart bulbs and reported that the worst one consumed more electricity in standby mode than during normal operation.
Let's break down where the power goes, how the protocols compare, and what China's new GB 30255-2026 standard changes for buyers.
What Happens When a Smart Bulb Is "Off"
A normal LED bulb cuts the circuit when you switch it off. Power consumption: zero.
A smart bulb is different. When you turn it off via the app or voice, the LED element stops emitting, but three internal blocks stay alive:
- Radio module — Zigbee, Wi-Fi, or Bluetooth stays connected to the network, waiting for commands. Typical standby draw: Zigbee 0.1–0.3W, Wi-Fi 0.5–1.5W.
- Driver auxiliary supply — the AC-DC stage keeps the MCU and radio chip powered. Isolated flyback designs typically draw 0.05–0.15W. Non-isolated or TRIAC-compatible designs can draw 0.3–2W.
- Indicator LEDs and sensors — a single status LED adds 0.05–0.2W. A always-on panel screen can draw 3–5W.
Add these three blocks together and you have the smart bulb's standby power.
What We Measured: 220V Mains, App Off
| Product Type | Standby Power | 20 Bulbs / Year | Annual Cost (US $0.15/kWh) |
|---|---|---|---|
| Non-smart LED | 0W | 0 kWh | $0 |
| Quality Zigbee | 0.2–0.5W | 35–88 kWh | $5–13 |
| Wi-Fi (mid-range) | 0.8–1.5W | 140–263 kWh | $21–39 |
| Cheap Wi-Fi driver | 2–4W | 350–700 kWh | $52–105 |
| Always-on panel screen | 3–5W | 525–876 kWh | $79–131 |
At first glance, the per-bulb numbers look tiny. Multiply by 20, 40, or 60 lights across a home, add gateways, routers, cameras, and smart speakers, and the baseline load becomes noticeable.
The protocol choice matters more than the brand:
- Wi-Fi: designed for high bandwidth, not low power. Wi-Fi radios draw 1W in standby to maintain heartbeat connection to the router. Difficult to deep-sleep.
- Zigbee: built for IoT. Most time spent in deep sleep, wake only when needed. Standby radio current as low as 3μA. This is the reason two AA cells can run a sensor for 12+ months.
- Bluetooth Mesh: ~0.2–0.5W. Limited range, less common in whole-home deployments.
The Hidden Power Hog: TRIAC Compatibility
Here is the dirty secret that costs you the most money.
To make smart bulbs compatible with legacy wall dimmers, many driver circuits keep a tiny conduction angle even when the bulb is "off." This micro-conduction is enough to keep the driver chip awake — adding 0.5–2W of standby power.
Worse, some configurations cause a faint "ghost glow" — the LED stays dimly lit in the dark even after you turn it off.
If your smart bulbs glow faintly when off, that is the problem. It is not just wasted energy. Long-term micro-conduction accelerates LED lumen depreciation.
China's GB 30255-2026: The New Red Line
The Chinese government just made standby power a regulated metric.
GB 30255-2026 (issued February 27, 2026, effective September 1, 2027) sets the first-ever mandatory standby power limit for indoor LED products: ≤ 1.5W.
Key changes from the 2019 version:
- Smart products now included — Wi-Fi, Zigbee, and Bluetooth bulbs all fall under the rule. Previously, the standard only covered non-smart LEDs.
- 1.5W hard limit — anything above this cannot be sold in China after 2027.
- Broader scope — downlights, high-bay fixtures, and double-ended LED tubes are all covered. Commercial and industrial buyers take note.
- Lifecycle efficiency — evaluation shifts from "lit-state energy efficiency" to "whole-life efficiency," including standby.
For Chinese export manufacturers, this rule will reshape product roadmaps. For international buyers, it signals the direction the rest of the world is heading.
Three Steps to Audit Your Home
Want to know how much your smart lights are stealing? Three steps:
Step 1: Measure it. Buy a plug-in watt meter ($10–20). Plug it between the wall and your smart bulb. Turn the bulb off via the app, not the wall switch. Read the standby power.
Below 0.5W = excellent. 0.5–1.5W = normal. Above 2W = consider replacing.
Step 2: Check the protocol. For new installations, prefer Zigbee or Matter-over-Thread over Wi-Fi direct. Standby power is typically 60%+ lower.
If you already have a Wi-Fi-based system, do not panic. The annual cost is maybe $20–40 for 20 bulbs. Not worth replacing. Just note it for your next project.
Step 3: Consider smart switch + dumb bulb. The lowest standby configuration: a smart switch (0.5W) controlling a high-quality LED bulb (0W standby). The trade-off: no per-bulb color or color-temperature tuning. But for most homes, this combination delivers the best balance of convenience and energy efficiency.
What NEXLAMP Does Differently
Our Zigbee smart drivers keep standby below 0.3W using low-power sleep + fast wake architecture. We use isolated flyback topology instead of non-isolated or TRIAC-based designs. Status LEDs are off by default — the user can enable them if needed.
The goal is for smart lighting to actually save energy, not quietly consume it around the clock.
The Bottom Line
Smart lighting is meant to make your home more efficient — lights off when no one is there, dimmed when daylight is sufficient. But if the standby power of your "off" bulbs is too high, the savings get eaten by phantom load.
Spend 30 seconds checking the standby spec before you buy. For whole-home installations, the protocol decision (Zigbee vs Wi-Fi vs Matter) is the single highest-impact choice you will make.
What is the standby power you measured on your own smart bulbs? Drop your numbers in the comments.
Data sources: IEA 4E Standby Power Annex field studies, GB 30255-2026 standard text, Lawrence Berkeley National Laboratory standby power research.
