What do compact fluorescent lamps save over 100 watt bulbs and 500 watt halogen lamps in an Alwar oil mill?

The Bureau of Energy Efficiency (BEE) Alwar manual swaps a 100 watt (W) bulb for an 11 W compact fluorescent lamp (CFL), saving rupees (Rs) 1,280 a year, and a 500 W halogen for an 85 W CFL, saving Rs 5,976, both at 3,000 hours. The manual prints a two month payback for each.

The two swaps

• 100 W bulb to 11 W CFL: saving 89 W. 0.089 kilowatt (kW) x 3,000 hours x Rs 4.8 = about Rs 1,280 a lamp a year. CFL price Rs 80 to 100. Cluster: 3,140 kilowatt hours (kWh), Rs 0.151 lakh, cost Rs 0.018 lakh.
• 500 W halogen to 85 W CFL: saving 415 W. 0.415 kW x 3,000 x Rs 4.8 = Rs 5,976. CFL price Rs 600 to 700. Cluster: 6,100 kWh, Rs 0.29 lakh, cost Rs 0.032 lakh.
• One lamp repays in under two months either way: Rs 80 to 100 against Rs 1,280 a year, and Rs 600 to 700 against Rs 5,976.

The lamp counts behind the totals

• 3,140 kWh at 267 kWh a bulb is about 12 bulbs. 12 CFLs at Rs 80 to 100 cost Rs 960 to 1,200, below the Rs 1,800 printed.
• 6,100 kWh at 1,245 kWh a halogen is about 5 lamps. 5 CFLs at Rs 600 to 700 cost Rs 3,000 to 3,500, which brackets the Rs 3,200 printed.
• So both rows are a handful of lamps, not a programme. Together they are 9,240 kWh, about 0.05% of the 186 lakh kWh the manual gives for the cluster.

Where the text and the sums differ

• The background text says a CFL uses about one third the energy of a bulb and about half that of a halogen. The sums use 11 W against 100 W (11%) and 85 W against 500 W (17%).
• The manual says each CFL gives the same lumens as the lamp it replaces, but prints no lumen figures. Our note, not the manual's: match the light level on the shop floor before you swap an 85 W lamp for a 500 W halogen.
• The 100 W swap is section I of the manual's contents, but it is not in the manual's list of measures or its summary table. The list of measures in section 3.4.1 instead has a 12th item, a slip ring to squirrel cage motor changeover, with no section. The summary table has neither. The Rs 95.76 lakh summary total leaves the bulb swap out.

Today

Our note, not the manual's: light-emitting diode (LED) lamps are now the usual swap for both. Compare watts, lumens and the driver, and count hours as above.

One bulb and one halogen

• Bulb: 0.089 kW x 3,000 hours = 267 kWh, x Rs 4.8 = Rs 1,282 a year (printed Rs 1,280)
• Halogen: 0.415 kW x 3,000 hours = 1,245 kWh, x Rs 4.8 = Rs 5,976
• Payback: Rs 80 to 100 / Rs 1,282 = 0.7 to 0.9 months. Rs 600 to 700 / Rs 5,976 = 1.2 to 1.4 months
• Carbon dioxide (CO2) at 0.675 kg a kWh, the financial year 2025-26 grid factor: 267 x 0.675 = 180 kg a bulb. 1,245 x 0.675 = 840 kg a halogen
• Both cluster rows: 9,240 kWh x 0.675 = 6,237 kg, about 6.2 tonnes

Watts, hours, tariff and prices are the manual's, at its date.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so last year's monthly kWh from your bills is on file to compare with the year after a swap. It does not split out lighting, count lamps or measure lux. A lighting sub-meter is custom, on request.

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• Do the Alwar manual totals add up
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Sources: Bureau of Energy Efficiency and Confederation of Indian Industry, Manual on energy conservation measures in the Alwar oil mill cluster (SAMEEEKSHA), Central Electricity Authority, CO2 Baseline Database for the Indian Power Sector (grid factor 0.675 kg CO2 per kWh, financial year 2025-26)

Last reviewed 2026-11-06. Figures are the manual's, from the Bureau of Energy Efficiency Small and Medium Enterprises (SME) programme, at its tariff and lamp prices. Get a current quote before you rely on a payback.