I would like to know which kind of cooling will be the most sustainable, that is, will use the least energy and cooling agents. I am considering summers with temperatures in the high 90's (35-37 Celsius), and about 800 square feet of apartment to cool, in two bedrooms and a large living room "slash" dining room and kitchen.

Would it be better to have a central unit cooling everything or 3 window A/C's for the large central room and bedrooms?

  • What are the night-time external temperatures, say at midnight, 3am, 5am?
    – 410 gone
    Feb 26, 2014 at 20:37
  • 2
    The manufacture of the units probably has a substantial impact on the sustainability too; 3 separate units is likely to have a higher environmental impact for manufacture. Feb 26, 2014 at 21:08
  • and will you have to run all the units all the time, or will you be running each one intermittently based on temperature and room usage?
    – Móż
    Feb 26, 2014 at 22:33
  • @EnergyNumbers The temperature doesn't drop much at night, at most around 5 degrees C.
    – MeloMCR
    Mar 5, 2014 at 20:42
  • @Ӎσᶎ Individual units would be used as needed, but there are not that many rooms in my particular case, just 3: two bedrooms and one big living room with a kitchen.
    – MeloMCR
    Mar 5, 2014 at 20:43

1 Answer 1


In general, one thing that is a huge factor is energy usage. Here in Indonesia central AC is not really used at all. Air conditioning is done room by room with wall-mounted split units (more units for large rooms than small ones). Coolant runs between the external component and the internal component. People don't build homes with central air in mind.

In general if you only have to cool the parts of your house you are using at the moment, you are going to use less energy to do it. If energy is the most important issue sustainability-wise, the multiple unit approach will win out.

I don't know about coolant leaks in comparison to the two approaches.

But the general point is that smaller units allow you to cool less. Central air requires that you cool your whole house at once and so my view is that it would be less sustainable.

  • Bigger units sometimes have variable-output cooling units, but that's an extra-cost option and they usually have a significant drop in efficiency as output drops. But I haven't run that comparison recently.
    – Móż
    Mar 5, 2014 at 21:01

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