How Long Should You Keep the AC On Before Turning It Off When Leaving Home? Taipower Reveals the Key to Saving Electricity

With summer heat persisting and summer electricity rates in effect, many people are concerned about soaring air conditioning bills, making "whether to turn off the AC when leaving home" a hot topic. Recently, a netizen asked on a social media platform whether it's more energy-efficient to keep an inverter air conditioner running continuously or to turn it off and restart it after being away for about three hours, sparking widespread discussion. In response, Taipower provided an answer through its official fan page: for short absences of about 30 minutes or less, it is recommended not to turn off the air conditioner. Taipower also debunked the online myth that "inverter ACs save the most electricity when left on 24/7."

Should You Turn Off the AC When Leaving for 3 Hours? Online Debate Rages, Taipower Provides the Correct Energy-Saving Answer

Recently, a user on Threads asked whether it's more energy-efficient to turn off the AC or keep it running when leaving home for 3 hours. The comment section quickly split into two camps. Those in favor of turning off the AC argued, "It's better to turn it off; if you're gone over 2 hours, you should switch it off," "If you're leaving for over an hour, turn it off, otherwise it consumes more power," and "I turn it off if I'm gone over an hour."

On the other hand, those who prefer leaving the AC on shared, "Don't turn off a high-efficiency inverter AC because the power used to restart it could run the AC for several hours," "I haven't turned off my AC since February, and my electricity bill for two months was only around 1,000 NTD," "I leave it on 24/7, and my monthly bill is no more than 1,500 NTD," "If it's an inverter AC, just leave it on or raise the temperature by one degree before leaving," and "Two AC units running 24/7 cost me about 3,500 NTD every two months, including common area electricity. It doesn't seem more expensive than turning them on and off."

The two sides held firm beliefs about the energy-saving limits of inverter ACs.

Does Turning Off the AC for a 3-Hour Absence Actually Use More Power? Taipower Explains: Keep It On for Under 30 Minutes, Switch to 'Fan Mode' or Raise Temperature

To address public concerns, Taipower's official fan page, 'Taipower Electricity Fan Club,' provided an answer. Taipower stated that for short absences of about 30 minutes or less, it is recommended not to turn off the air conditioner. The reason is that each time the AC restarts, the compressor requires higher power to operate, resulting in relatively high instantaneous power consumption. If you're only away for a short time, frequently turning the AC on and off may actually increase power usage.

However, if you plan to be away for more than 30 minutes, especially several hours or longer, Taipower recommends turning the AC off completely, as the total electricity consumption is usually lower than keeping it running continuously.

What Does Taipower Recommend? Time-Based Guidelines and 3 Energy-Saving Tips

In addition to timing the on/off cycles, Taipower also shared several daily energy-saving methods to effectively reduce summer electricity bills:

- Set the air conditioner temperature between 26°C and 28°C. - Use electric fans or circulators to accelerate cooling efficiency; this can lower the perceived temperature by about 2–3°C. - When leaving briefly, switch the AC to fan mode or slightly raise the set temperature to reduce frequent compressor startups.

| Time Away | Recommended Action | Reason | |-----------|--------------------|--------| | Around 30 minutes or less | Do not turn off AC; switch to fan mode or raise temperature | Avoids extra power consumption from compressor restarts | | More than 30 minutes | Recommend turning off AC completely | Continuous temperature maintenance still consumes power, and cumulative usage is usually higher | | Long absence (several hours or more) | Must turn off AC | Running continuously with no one home wastes electricity |

Is It True That 'Inverter ACs Save More When Left On 24/7'? Taipower: Leaving It On for 10 Hours Costs More

Taipower stated that online claims such as "leaving an inverter AC on all day saves more than turning it off" and "no need to turn it off even when away for 10 hours" are common misconceptions. Whether it saves electricity depends not only on whether the AC is inverter-type but also on the duration of absence, indoor-outdoor temperature difference, home insulation, and usage habits. It's not always optimal to keep the AC running continuously.

Although inverter ACs are more energy-efficient than non-inverter models, this doesn't mean they can run indefinitely without cost. As long as the AC is on, the compressor will repeatedly operate to maintain the set temperature, and the longer it runs, the higher the cumulative power consumption. Although restarting causes a brief spike in power use, it does not outweigh the electricity consumed during prolonged continuous operation. If no one is home or there's no immediate need to use it, turning off the AC is the more energy-efficient choice.