Is it cheaper to leave portable AC on?
No, it is not cheaper to leave portable AC on. The cheapest way to use a portable AC is to run the unit for 4 hours a day every morning. Leaving a portable AC on is only cheaper if you are already using it for 15+ hours a day.
You’ll read some recommendations online that its cheaper to leave your portable AC on because the start-up process uses a lot of energy and strains parts. It is true that minimizing the number of times you turn your portable AC on will extend its lifespan.
However, any savings due to this extended lifespan are outweighed by the high cost of leaving your portable air conditioner running 24/7.
Another potential argument in favor of leaving your portable air conditioner running is that your portable AC will save money by not having to bring your home up to temperature.
It is true that you’ll save energy by keeping your home at a comfortable temperature compared to having to cool your home down. But this only makes sense if you’re already going to use your portable air conditioner for more than 15 hours a day.
Let’s break down the math.
A portable air conditioner uses .9 kWh – 1.4 kWh per hour. Let’s assume electricity costs of $0.13 – $0.26 per kWh. That means you’ll spend $0.11 – $0.36 to run a portable air conditioner for one hour.
So imagine you currently use your portable air conditioner for 15 hours and you want to shift to using it continuously to extend the lifespan of your device. That means going from spending $1.65 – $5.40 to spending $2.64 – $8.64 for your daily portable air conditioner use.
That’s a relatively small jump in costs that would likely be outweighed by the money you would save by extending the life of your portable air conditioner.
But if you only use your portable air conditioner for 4 hours a day (what we recommend for maximum energy efficiency), this jump is much more significant. You would be going from spending $0.44 – $1.44 to $2.64 – $8.64.
That’s just not worth it for some improvements in efficiency and the lifespan of your air conditioner.
Mark is a journalist who has written about home products for two years. He holds a masters degree with distinction from the London School of Economics and an undergraduate degree from the University of Edinburgh.