Smart Lighting Automation: How Much You’ll Actually Save on Your TNB Bill

Every smart lighting article promises you'll save money. Almost none of them show you the arithmetic.

So here it is: the real numbers, including the part that works against you, worked out using TNB's current tariff.

If you already use LED bulbs, the honest answer might surprise you.

First: what you actually pay per unit

Since 1 July 2025, TNB's domestic bill has been split into separate charges instead of the old tiered blocks. For a home using up to 1,500 kWh a month (almost every household), each kWh costs:

On top of that there are three things that change your bill:

• Retail charge: RM10 a month, waived if you use 600 kWh or less.
• Energy Efficiency Incentive (EEI): an automatic rebate for homes using 1,000 kWh or less. The less you use, the bigger the rebate per kWh.
• Automatic Fuel Adjustment (AFA): a monthly surcharge or rebate of up to ±3 sen/kWh, which replaced the old ICPT. Homes using 600 kWh or less don't pay AFA surcharges.

Check these against your own latest TNB bill before you trust them. The new bill lists each charge on its own line, and your bill is the authority, not this article.

What this means for savings

Under the old tiered tariff, heavy users saved far more per kWh than light users. That's no longer true. With a roughly flat 44.43 sen/kWh, every kWh you cut is worth about the same, whether you use 300 kWh or 1,200 kWh a month.

Cut 40 kWh a month and you save about 40 × 44.43 sen ≈ RM17.77, before the rebate and fuel adjustment.

Two thresholds can make a cut worth more:

• Just above 600 kWh? Getting under 600 kWh also removes the RM10 retail charge and any AFA surcharge.
• Under 1,000 kWh? Using less can move you into a band with a bigger EEI rebate. Look at the EEI line on your bill to see what you're getting now.

So before you buy anything, look at your bill and find your monthly kWh. It tells you whether you're near one of those thresholds. But for most homes, what decides whether smart lighting pays off is what you're replacing and how much light you waste, not which tier you're in.

The part nobody mentions: smart bulbs use power when they're off

A smart bulb is never truly off. It keeps its Wi-Fi radio alive so it can hear you switch it on, which typically draws somewhere around 0.3 to 0.5 watts continuously. Check the spec sheet, or measure your own bulbs with a cheap plug-in energy meter.

That sounds trivial. Across a house, it adds up:

Ten smart bulbs at 0.4W, running 24 hours a day, 30 days a month:

0.4W × 10 × 24 × 30 = 2.88 kWh per month

At 44.43 sen/kWh that's about RM1.28 a month, or around RM15 a year, just for the bulbs being reachable.

This isn't a reason to avoid smart bulbs. It is a reason to be sceptical of any article claiming pure savings without mentioning it, and a reason not to put smart bulbs in rooms you light twice a month, where the standby draw can exceed what you save.

Where the savings actually come from

There are three sources, and they're wildly unequal in size.

1. Replacing incandescent or halogen bulbs: large

If you still have old filament or halogen bulbs anywhere, this dwarfs everything else in this article.

A 60W incandescent running 5 hours a day:

60W × 5h = 300Wh a day = 9 kWh a month

A 9W LED doing the same job at similar brightness:

9W × 5h = 45Wh a day = 1.35 kWh a month

Saving: 7.65 kWh per bulb per month.

Across five bulbs, that's 38.25 kWh a month: about RM17 a month at 44.43 sen/kWh.

But notice what's doing the work here. That saving comes from LED, not from smart. A basic LED bulb costing a fraction of the price saves you exactly the same amount. Anyone selling you a smart bulb on these figures is taking credit for something LED technology did.

2. Automation preventing waste: moderate, and the real smart-specific saving

This is the only saving that genuinely belongs to smart lighting, and it depends entirely on how wasteful you currently are.

Say three bulbs in your house routinely get left on for four hours a day when nobody's in the room: the porch light burning until noon, the bedroom light on all afternoon, the hallway on all night.

3 bulbs × 9W × 4h = 108Wh a day = 3.24 kWh a month

Now subtract the standby draw of the whole system. With eight smart bulbs at 0.4W:

8 × 0.4W × 24h × 30 = 2.30 kWh a month

Net saving: 0.94 kWh a month, or about 42 sen.

Read that again, because it's the honest finding this article exists to deliver: if you already use LED bulbs and you're reasonably careful about switching them off, smart bulbs will save you almost nothing. The standby draw eats most of the automation gain.

The maths only turns clearly positive when the waste is large: an outdoor light left on all night, a whole floor lit in an empty house, someone in the household who never switches anything off.

3. Dimming: small but real

Running an LED at 50% brightness uses roughly half the power, unlike old incandescent dimmers, which wasted much of the difference as heat.

Living-room lights at 60% in the evening instead of 100% is a saving you'll barely notice, visually or on the bill. It's worth setting up because it's free, not worth buying anything for.

A worked example

Here's an example household. The figures are illustrative, so swap in your own: a four-bedroom terrace, three people, 650 kWh a month, paying about 44.43 sen/kWh.

They install eight smart bulbs. Five replace 60W halogens that ran 5 hours a day. The other three replace LEDs.

Savings:

• Halogen → LED on five bulbs: 5 × 7.65 = 38.25 kWh a month
• Automation cutting genuine waste (porch light overnight, roughly 3 hours a day at 9W): 0.81 kWh a month
• Evening dimming across three bulbs: roughly 0.5 kWh a month

Costs:

• Standby on eight bulbs: 2.30 kWh a month

Net: 37.26 kWh a month saved.

At 44.43 sen/kWh: about RM16.55 a month, or roughly RM199 a year.

Against a spend of, say, RM320 for eight decent smart bulbs, that's payback in roughly 19 months. This household also drops from 650 to about 613 kWh. If it got under 600 kWh, the RM10 retail charge would go too.

Now run the same household without the halogens, with everything already LED:

Net: 0.81 + 0.5 − 2.30 = −0.99 kWh a month. They lose about 44 sen a month.

Same house. Same bulbs. Same automations. The entire difference is what was there before.

Five automations worth setting up, ranked by what they actually save

1. Outdoor and porch lights on a sunset/sunrise schedule. The biggest single win in most homes, because outdoor lights are the ones most often left burning into daylight. Use sunset and sunrise triggers rather than fixed times, so it adjusts itself through the year.

2. "Everyone's out": all lights off. Ties lighting to your phones leaving the house, and catches the expensive mistake of lighting an empty home all day.

3. Motion-triggered hallway and stair lights at low brightness. Set them to 15–20% between midnight and 6am. It beats someone switching on a full-brightness light and leaving it on, and it's far pleasanter at 3am.

4. A hard "lights out" time. Everything off at, say, 1am regardless. A blunt instrument that catches every case you forgot to plan for.

5. Evening dimming. Living areas to 60% after 8pm. A tiny saving for zero effort, and it makes the room nicer.

Three automations that sound clever and save nothing

Colour changing. No meaningful power difference between colours, and most people stop using it within a fortnight.

Sunrise wake-up fade. Genuinely lovely, but it uses slightly more power than just switching the light on, since the bulb runs for twenty minutes instead of two. Buy it for the experience, not the bill.

Smart bulbs in rarely used rooms. Store rooms, guest bedrooms, the back bathroom. You light them for a few minutes a week while paying standby 24/7. These are the rooms where smart bulbs genuinely cost you money. Put basic LEDs there.

So should you buy them?

Buy for savings if you still have incandescent or halogen bulbs, or there's genuine waste in your home: lights burning in empty rooms, outdoor lights on all night. In those cases the payback is real, typically inside two years. If you're just above 600 kWh a month, getting under it is a bonus.

Buy for convenience if you're already fully LED and reasonably disciplined. That's a perfectly good reason to spend money. Waking to a light that fades up, switching the house off from bed, coming home to a lit porch: these are genuinely nice, and nobody needs to pretend they're an investment.

Don't buy if you're already on LEDs and expecting the bulbs to pay for themselves. They won't. You'd be spending a few hundred ringgit to save a few ringgit a year. Air-conditioning usually dominates Malaysian electricity bills, so that's where efforts to cut usage tend to pay off more.

The honest summary

Smart lighting is a convenience product that sometimes saves money, not a savings product that happens to be convenient. That's less exciting than what most articles tell you, but it's what you'd want a friend to tell you before you spent RM300.

Run the numbers against your own bill: find your monthly kWh, check the EEI and AFA lines, and count how many non-LED bulbs you still have. That ten-minute exercise will tell you more than any review.