The Secret to Cutting 90% of Your Air Conditioning Electricity Bill: A Complete Guide to 'Fan Mode Automation'

Summer 2025 has arrived with record-breaking heatwaves—and along with them, higher electricity rates. If you’re already hesitant to pick up your air conditioner remote, you’re not alone. But this article is not another vague advice on “just use less.” Instead, we’ll dive into a highly specific and professional method to reduce your electricity bills by up to 90% using smart home automation—without sacrificing comfort. By intelligently controlling the main source of energy consumption in your A/C, and effectively utilizing ‘fan mode,’ you can stay cool and save big.

I used to come home after work and leave the A/C on overnight—only to sigh at the sky-high utility bill the next month. But now, with the help of smart home automation, I’ve dramatically lowered my monthly air conditioning costs. In this post, I’ll share everything I’ve learned, step by step.

What You'll Learn

• Understanding the A/C's biggest energy consumer: the outdoor unit (compressor)
• Comparing energy usage: Cooling vs. Fan vs. Dry Mode
• Best automation strategies for legacy and inverter-type air conditioners
• Step-by-step guide to setting up smart automation (incl. smart plugs, IR remotes)
• Expert checklist and FAQ to ensure a smooth experience

Understanding the Heart of Your A/C: The Compressor

To save on electricity, you must first understand how your air conditioner works—specifically, the compressor (outdoor unit), which consumes roughly 80-90% of your total A/C power usage.

• Cooling Mode: Absorbs warm indoor air, passes it through refrigerant, and expels heat outdoors via the compressor—this consumes a lot of power.
• Fan Mode: The compressor stays off. Only the indoor fan circulates air like a standard electric fan. This consumes just 5-10% of the energy used in cooling mode.
• Dry Mode: The compressor cycles on and off to remove humidity. It uses less energy than full cooling but much more than fan mode.

The takeaway? To save on electricity, minimize compressor runtime. This is where smart automation and fan mode become powerful tools.

Proven by Data: The Power of Fan Mode Automation

Here’s a real-world comparison of power consumption based on a 6-pyeong (~21m²) wall-mounted A/C unit:

Mode	Avg. Power Use (kWh/hr)	Monthly Bill (8hr/day)	Operation Method
Cooling Mode	1.0 ~ 1.8	₩50,000 ~ ₩85,000	Compressor running full time
Cooling + Fan (Auto)	0.4 ~ 0.7	₩20,000 ~ ₩35,000	Compressor runs only when needed
Fan Mode Only	0.04 ~ 0.08	₩2,000 ~ ₩4,000	Indoor fan only

* Based on low-voltage residential power rates (2nd tier). Actual rates may vary by household.

Tailored Automation Strategies for Your A/C Type

Legacy (Fixed-Speed) A/C

These units operate at 100% power until the desired temperature is reached, then shut off completely. The cycle repeats.

Best approach: Use a smart IR remote to switch between cooling and fan mode automatically based on room conditions.

Inverter A/C

Inverter units adjust their output to maintain a set temperature efficiently. They operate at reduced power (e.g., 20–40%) rather than turning off entirely.

Best approach: Instead of frequent ON/OFF toggles, allow the A/C to manage efficiency. However, automate fan mode or power off when no one’s home or when it gets too cold.

Fan Mode Automation: Step-by-Step Setup

Step 1: Gather Your Tools

• Temperature/Humidity Sensor: Essential for triggering automation. (e.g., Xiaomi, Aqara, Tuya)
• Smart IR Remote Hub: Needed for legacy A/Cs to send commands via smartphone (e.g., SwitchBot Hub Mini, Tuya IR Blaster)
• Smart Home Hub App: The brain of your automation (e.g., SmartThings, Google Home, Apple HomeKit, or Home Assistant)

Step 2: Automation Scenarios

Set up these rules using Home Assistant, SmartThings, Tuya, or Google Home:

Condition (IF)	Action (THEN)	Required Devices
Room temp ≥ 27℃	Turn on Cooling Mode @ 24℃	Sensor + IR Remote
Room temp ≤ 24℃ for 10 minutes	Switch to Fan Mode	Sensor + IR Remote
No one at home (via GPS)	Turn off A/C	Phone GPS + Hub App
Power draw ≤ 100W for 1 hour	Turn off A/C	Smart Plug or Power Meter

Pro Tip: Start simple, then add rules like: “Maintain 26℃ while sleeping, switch to fan,” or “Use Dry Mode when humidity > 70%.”

Expert Checklist for Flawless Automation

• Sensor Placement: Avoid direct airflow or sunlight. Place where average room temperature is measured.
• IR Signal Strength: Ensure a clear line of sight between IR remote and A/C unit.
• Wi-Fi Stability: All devices should be on a reliable network. Use extenders if needed.
• Avoid Rule Conflicts: Prioritize conditions like “27℃ triggers A/C ON” vs “10 PM triggers OFF.”

FAQ: Your Top Questions Answered

Q1: Aren’t inverter A/Cs more efficient if left on constantly?

A1: Yes, but not always. If no one’s home or the room gets too cold, it’s still a waste. Automation helps minimize unnecessary use while maximizing inverter efficiency.

Q2: Is it safe to cut A/C power using a smart plug?

A2: Ideally, use IR remote signals to turn off the unit. Sudden power cuts may interrupt internal drying cycles. Use smart plugs for monitoring or backup control.

Q3: Fan Mode vs Dry Mode—Which is better?

A3: It depends. On hot days, use cooling first, then fan to maintain. During humid but cool weather, Dry Mode is more comfortable and energy-efficient. Automate based on both temperature and humidity.

Smart Homes Are No Longer Optional

A/C automation is more than just a tech novelty—it’s a practical and smart solution for protecting your wallet and the planet in this era of climate and economic pressure. With the methods shared here, you’ll experience a seamless, energy-saving summer with comfort intact.

Try the automation guide above. Once set up, it runs by itself, keeping your home cool while saving you money—all without lifting a finger. Wishing you a cool, efficient summer!