How much power do timers and an efficient cooling tower (better fan blades) save on a Jamnagar brass extrusion cooling tower?

In the Bureau of Energy Efficiency (BEE) Jamnagar manual, a timer that cuts a 5 kilowatt cooling tower fan from 10 hours to 8 saves 2,520 kilowatt hours (kWh) a year for rupees (Rs) 0.10 lakh. Better blades save 3,300 kWh for Rs 0.30 lakh. Together they save less than the two added.

The two fixes

• Timer: the manual says towers "operate continuously irrespective of water temperature", yet its table uses 10 hours a day, and the table, not the text, is what is used here. Fan motor 5 kilowatts rated, 4.2 input. Hours a day fall from 10 to 8, saving 8.40 kWh a day, 2,520 a year, which implies 300 working days. At Rs 6 a kWh that is Rs 0.15 lakh. Cost Rs 0.10 lakh, payback 0.67 years.
• Better blades (the page's reading): the manual's measure in Table 3.16 is "replacing conventional cooling tower system with energy efficient cooling tower system" for Rs 0.30 lakh. Aluminium fan blades are only its background, so calling it a blade swap is my reading. The efficient system cuts the fan input from 4.20 to 3.10 kilowatts, saving 1.10 over 3,000 hours: 3,300 kWh, Rs 0.20 lakh. Payback 1.50 years. It also lists lower noise.

They share one fan, so do not add them

Both rows start from 4.2 kilowatts for 3,000 hours (10 hours x 300 days), which is 12,600 kWh. With both fixes the fan would draw 3.10 kilowatts for 2,400 hours (8 x 300), which is 7,440 kWh. The saving is 5,160 kWh, not 2,520 + 3,300 = 5,820. That is my arithmetic from the manual's inputs, not a figure the manual prints. Together they cost Rs 0.40 lakh and save about Rs 0.31 lakh a year, a payback near 1.3 years.

Across the cluster

Table 5.1 counts 120 units for each fix: 302,400 kWh for timers and 396,000 for blades. At 0.675 kilograms of carbon dioxide (CO2) a kWh for financial year (FY) 2025-26, one tower saves about 1.7 tonnes with the timer and 2.2 with the blades. The cluster totals are about 204 and 267 tonnes. Neither fix was short-listed for a detailed project report.

What the timer saves only if

• The water temperature stays in range with the fan off for two hours. The manual says the timers switch fans on and off by water temperature, so check the die and press cooling alarms, not just the bill.
• Your tower really runs 10 hours a day today. If it already cycles, the saving is smaller.

One tower, both fixes (estimate)

• Today: 4.2 kilowatts x 3,000 hours = 12,600 kWh
• Both: 3.10 kilowatts x 2,400 hours = 7,440 kWh. Saving 5,160 kWh
• CO2: 5,160 x 0.675 = about 3.5 tonnes a year. Money at Rs 6: Rs 30,960
• Payback on Rs 0.40 lakh: 0.40 / 0.31 = 1.3 years

Inputs are the manual's. The combined figures are the author's arithmetic. Grid factor is the Central Electricity Authority's (CEA) FY 2025-26 figure.

What Senseible does here

Self-serve, Senseible reads fuel invoices and electricity bills into monthly records; machine meters are custom, on request. Electricity units by month are on file, and the hours of use come from your own log.

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Sources: BEE, Manual on energy conservation measures in brass cluster Jamnagar (Winrock International India), CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0

Last reviewed 2026-11-06. Figures are from BEE's Jamnagar manual, which prints no year on the pages used. Re-check the grid factor for the year of your bill.