This $8 Flawless Homemade Air Conditioner Is Flawed

May 25, 2016
Consumer Reports: Can a Homemade Air Conditioner Keep You Cool?

After multiple runs using 8 to 12 pounds of three different forms of ice—cubes, reusable ice packs, and a frozen gallon jug of water—the homemade air conditioner was able to lower the temperature of a small room by only 2° to 3° F, and within 30 minutes the room temperature began to rise again.

Consumer Reports has missed a very important point here. What's making the ice? It better not be the refrigerator sitting in the same room. Making ice requires energy. The more ice made the more energy is needed. Since a refrigerator is normally not able to expel that extra energy out the window like a typical air conditioner does, that energy must instead heat the room. This is above and beyond the offsetting cooling ability of the ice that was created, since refrigerators are not 100% efficient, nor is it possible that they ever will be.

This is why it is a bad plan to leave a refrigerator door open in an attempt to cool a kitchen. It will do the opposite. The kitchen will actually get warmer.



From the comments:

As to your freezer working harder to freeze the ice all I can say is LOL! It's common knowledge that a full freezer is more efficient than a half empty one! but that's easy enough to check for yourself - i'm betting your freezer will come on at the same or nearly the same rate - what really makes your freezer work harder is opening the door, DUH! Your freezer HAS to come on at a certain rate no matter what anyway. - female small

Science says a full freezer is more efficient than a half full freezer because when the door is opened less cold air can escape and less warm air can enter.

Science also says that a half full freezer is even less efficient when the door is opened, the cold air escapes, and warm water bottles are used to fill the empty space.

I say that when a freezer is entirely filled with warm bottles, the refrigerator screams in pain, and an angel in heaven burns its wings off. That's assuming that heaven is a very small studio apartment containing a very large temperamental refrigerator, one $8 homemade air conditioner, and a sole angelic tenant who believes in miracles. Burn, baby burn.

But hey, maybe that's just me. Hahaha!

P.S. We use two large industrial fans purchased at Costco to cool our two story house. We put the fans on the second floor up against the screens of two windows. The fans point outwards to push the heat out in the evenings. The cool air is then drawn in through our downstairs windows, as if by magic. Why push out instead of pull in? Most fans push a column of focused air but pull from multiple directions. You can therefore generally push more air through a screen than pull through it. That's been my experience anyway. Give it a try!