This is awesome, but wouldn't it be more effective to just super-insulate homes? With a super-insulated home your need for cooling (and heating) would drop dramatically. All it would take to accomplish this is a change to building codes. IRC insulation requirements here in the USA are pretty good, but not what I would call "super-insulated" levels. Perhaps next up can be an insulation award?

I would agree passive home design would seem to be a better way to avoid the need for the air conditioner, - so how could you do this with local sourced materials at a low cost for different countries. It is likely a more efficient air conditioner is achievable, but whether anyone wants to improve efficiency by a factor of five and yet only get twice the price would be the key item I can forsee. Saving the planet versus making money always still seems to be a key stumbling block, but I am still hopefull.

The X prize didn't have a "set of carefully designed criteria." They kept moving the goal posts, which is why I won't enter this one.

There's a $3 million prize for better AC tech? Wow! And I always thought the prize for better tech was in being able to sell it to, you know, actual consumers. If you could make a buck on each of those 3.3 billion AC units (or even half) in your forecast, that would dwarf this silly prize. Customer WILL buy it, if it saves them money (or gives greater comfort, less noise, or whatever). The only way the prize makes sense is to pay for tech that people don't want. But Mr. Branson got his name in the news, for whatever that's worth.

I used to have a refrigerator that worked with a 100 W electric element, add a 250 W fan, and claim your prize! (My aunt, who lived in an old house with no electricity, had one that used paraffin, or kerosene.)

You can make any air conditioner as efficient as you want by making it bigger. There is a size that minimizes life cycle cost. There are subsidies that promote the purchase of a larger unit. Market entry promotes a less efficient unit. The same thing goes for a house. The house with minimum life cycle cost will have a bit more insulation that you normally see but not be "super insulated" because that requires non-standard construction. Also, most houses were built for market entry.

Just look to nature: https://youtu.be/620omdSZzBs ...and claim ur prize! (or just sell to the highest bidder and so u can just buy out Sir Branson and his paltry Virgin! ☻)

I have another problem, the latent heat of vaporization of water at 2260 kJ/kg is too much. It takes too much power to boil water. I want Branson to offer a $3 million prize to whoever can lower the latent heat of vaporization of water, please.

"...LED lights that operate at up to 89 percent efficiency...."
Dubious. Link, please. . One watt of 555nm wavelength light is 683 lumens. I have seen some research LEDs claiming 300 lumens per watt, which still has a way to go before it can claim 89% efficiency...even if these were 'available'.

Grunchy, you requested a way to lower the latent heat of vaporization of water. Good news, no need to get Branson involved. The solution is available without delay... Simply increase the pressure.