Converting a house to LED, in the right order

Short answer. Converting twelve incandescent bulbs to 12 W LEDs saves roughly 158 units a month at typical usage, and payback is measured in weeks. Converting from energy savers saves nearer 18 units — real, but far less dramatic, and worth doing as bulbs fail rather than all at once.

Applies: All year · Cost to do: Small one-off cost · Indicative saving: around 100 units a month

The arithmetic

Twelve incandescent bulbs at 100 W, averaging five hours a day, is 6 units a day and 180 units a month. The same light from 12 W LEDs is 0.72 units a day and about 22 units a month.

That saving continues every month indefinitely, and it is one of the few interventions that costs a few thousand rupees and pays back within a season.

Order by hours, not by room

Convert the lights that run longest first. Outdoor and corridor lighting, then the kitchen, then living areas, then bedrooms, then rooms used occasionally.

A guest room bulb burning two hours a month saves almost nothing whichever technology it uses. Replacing it first is the most common way people conclude that LED conversion 'did not help'.

Buying bulbs that survive Pakistani voltage

Cheap LED bulbs fail early here, and the cause is almost always the driver circuit rather than the diodes. Wide input voltage tolerance and a metal rather than plastic heat sink are the two things worth paying for.

A bulb that fails in eight months has not delivered the saving its price assumed. Buying the cheapest available repeatedly costs more than buying a decent one once.

Do not install an ordinary LED bulb in a fully enclosed fitting — trapped heat destroys the driver, and that is the second most common cause of early failure.

Tube lights need the ballast bypassed

An LED replacement tube dropped into an unmodified fluorescent fitting leaves the magnetic ballast in circuit, still dissipating ten to twelve watts as heat and shortening the LED's life.

Bypassing the ballast is a straightforward job for an electrician, and it is where the saving actually comes from. Skipping it is the standard half-measure.

The cooling bonus

An incandescent bulb turns most of its energy into heat. In an air-conditioned room that heat is then removed at further cost, so the true saving from conversion in a cooled room exceeds the lighting arithmetic on its own.

What to actually do

List every light in the house with its rough daily hours, and convert in descending order of hours.
Match brightness in lumens rather than by wattage habit — over-lighting in LED is still waste.
Buy bulbs with wide input voltage range and metal heat sinks.
Have the ballast bypassed when fitting LED tubes.
Avoid ordinary LED bulbs in fully enclosed fittings.
Choose warm white for living areas and cool white for kitchens — a bulb people dislike gets replaced with an old one.

Frequently asked questions

Is it worth replacing working energy-saver bulbs with LED?

The saving is roughly 18 units a month across twelve bulbs, which is real but modest. Replace them as they fail rather than all at once, unless the bulbs are in high-hour locations where the payback is faster.

Do LED bulbs work well on a UPS or inverter?

Very well. Their low draw means a modest battery bank runs a house's lighting for many hours, which is why LED conversion is usually the first step before sizing any backup system.

Related guides

Standby power, in honest proportion — all year, costs nothing
Staying under 200 units and keeping protected status — all year, costs nothing

The numbers behind this

All 10 guides are ranked by value in the index. To see what your own house needs, run the efficiency audit.