How to cut your summer AC bill in Bangladesh

A 1.5-ton AC is the single biggest line item on most Dhaka summer bills. By June it can be 60% of household consumption and easily pushes a normal medium user into the 401–600 unit slab — where every extra kWh costs around ৳15. The good news: the things that actually work are well known, and most of them are free or pay back in a single season.

How much electricity an AC actually uses

A 1.5-ton (18,000 BTU) non-inverter AC has a rated power draw of about 1,800 W. Run it 8 hours a day at a 60% duty cycle and you use roughly 260 kWh a month. An inverter unit with the same cooling capacity, stabilised at a 25°C set-point, might average about 700 W once the room is cool. That brings monthly use down to about 170 kWh. A 35% reduction.

Put both numbers in the bill calculator. For an illustrative 200 kWh of other household use, total consumption falls from 460 to 370 kWh. At June 2026 LT-A rates, energy cost falls from ৳4,229.60 to ৳3,040.40 — ৳1,189.20 a month before VAT, or ৳4,756.80 over four months. Against an assumed ৳10,000–20,000 purchase premium, that takes roughly three to five such summers to recover.

Inverter vs non-inverter

What's actually different

A non-inverter AC's compressor runs at full speed when on and shuts off when the room hits the set-point. The on-off cycling means it regularly draws full rated current and overshoots the set-point before stopping. An inverter compressor continuously varies its speed, holding the room at the set-point with much less peak draw. The cost: an inverter unit of the same tonnage is usually ৳10,000–20,000 more expensive.

When the math works

The more hours you run it, the faster an inverter pays back. A bedroom unit on for four hours at night is marginal; a drawing-room unit running ten hours during work-from-home is a clear win. Below three hours a day a well-sized non-inverter is economically sound too.

Sizing: how many BTU do you actually need

Bigger isn't better. An over-sized AC cools the room before it gets a chance to pull humidity out, leaving the air sticky and pushing you to lower the set-point further. A correctly sized unit runs longer at lower load, properly dehumidifies, and lets you sit comfortably at 26°C instead of 22°C.

A Dhaka-ish rule of thumb:

Bedroom up to 120 sq ft — 1.0 ton (12,000 BTU)
Bedroom 120–180 sq ft — 1.5 ton (18,000 BTU)
Drawing room 180–250 sq ft — 1.5–2.0 ton
Open-plan above 250 sq ft — 2.0–2.5 ton

Add 10% to the BTU if the room has a west-facing glass window, a tin roof, or three or more regular occupants. Subtract 10% if it's deeply shaded.

Set-point discipline

Each degree below 26°C costs roughly 5–7% more energy, because the gap to outside air widens. The difference between 24°C and 26°C for 8 hours a day on a 1.5-ton unit is about 35 kWh a month — roughly ৳320 in the 201–300 slab.

Two simple habits help:

Keep the AC at 26°C and run the ceiling fan on medium. Air movement does the work of a lower set-point at a fraction of the cost.
Use timer or sleep mode at night. Most modern units have a sleep mode that raises the set-point by 1°C an hour after the room cools — invisible to a sleeping user.

Maintenance that actually helps

Two maintenance steps make a difference. The rest is mostly cosmetic.

Monthly filter cleaning

A dust-clogged filter raises power draw by 10–15%. Open the front cover, rinse the filter in cold water, dry in shade, refit. Five-minute job. Set a reminder on the 1st of every month through summer.

Annual condenser coil cleaning

The outdoor unit's condenser dissipates heat through fine aluminium fins, which clog up with dust, smoke, and pollen over a year. A technician cleaning the coil brings efficiency close to factory spec. Most technicians charge ৳1,500–2,500 for a residential clean, and the payback is usually two months.

Insulate what you can

Air conditioning is fighting heat intrusion. The faster heat gets in, the harder the AC works. A few cheap interventions give the biggest returns:

Blackout curtains on west-facing windows from 1 PM to 5 PM.
A door-bottom seal so AC-cooled air doesn't escape into the corridor.
Reflective film on directly sunlit glass. ৳200–300 per pane, cuts solar heat gain by up to 60%.

Together these steps cut AC's monthly energy by another 8–15% in a typical Dhaka flat.

The wattage math, concretely

Work out your own numbers. Take the AC's rated power (printed on the spec plate, usually 1,500–1,800 W for a 1.5-ton), multiply by hours per day and days, multiply by 0.001 to convert to kWh, and put it into the calculator alongside your other use. See what slab you land in. Then run it again with the inverter/set-point/maintenance optimisations and compare. This exercise often surfaces ৳1,500 a month in savings for heavy AC users — without compromising comfort.

A one-day usage profile

A realistic profile for a 1.5-ton inverter AC in a 120 sq ft Dhaka bedroom across the day.

10 PM to 7 AM. Sleeping, set-point 26°C, sleep mode on. Average draw about 650 W, roughly 5.8 kWh in 9 hours.
7 AM to 1 PM. AC off, curtains and fan doing the work. 0 kWh.
1 PM to 5 PM. Work-from-home, west-facing window curtained. Set-point 26°C, average draw about 900 W. About 3.6 kWh in four hours.
5 PM to 10 PM. AC off, fan running. 0 kWh.

Total daily use about 9.4 kWh, monthly 282 kWh. The same bedroom with a non-inverter unit would be about 420 kWh. A 33% difference.

Pick the right-sized unit. Choose inverter if it runs more than three hours a day. Hold the set-point at 26°C with a fan. Clean filters monthly. Have the condenser cleaned each spring. Insulate the worst window. Done together, these steps cut a typical Dhaka summer bill by 25–35% every year. Free changes start saving immediately; calculate the payback before buying new equipment.