What is the difference between split AC and window AC. Which AC is less power onsuming with less pollution?

Question

I am searching a enviromently friendly AC to save the world from hotting and with less power consuming. Alternatevely any alternative powered (solar, wind energy etc) AC is in the market or for developing . Further I want to know the mertits and demerits os window and Split ACS

Answer 1

In one sense, window ACs are less efficient due to air leakage around the window and a typically lower EER rating ( BTU/Watt) than than you find with split systems.  They are also noisey (a form of pollution).

On the other hand, a couple of small window units can be scattered around a home and used to cool only the rooms currently occupied.  In this way they can save energy over central air units.

Answer 2

To be even moderately efficient an a/c unit has to pull its inside air from close to the top of the living space, to get the hottest air. That is not likely for a window unit.

Next, the heat dissipation may need to be done out of doors, away from the wall, in the shade. The optimum unit will pump heat from a bank of water during the night into cooler night air, and then during the day will use the cold water to cool the house.

But so much depends on having the house properly insulated, designed to exclude sunshine. It makes no sense to try to do it all with choice of a/c. We can undo all the good work in choosing a great a/c by merely having large regular glass windows taking in light from the bright sky, let alone from a rising or setting sun.

Having a blacktop driveway beside the house to collect thousands  of kWh of heat during the day to radiate it into the house all night is not conducive to economic a/c use. Dark red brick exposed to the sun outside, no shade trees, no creeping vines, Roof crawl spaces that are not ventilated adequately, No reflector sheets between ceiling and insulation above it... so many very significant design considerations make such big differences.