Still, I don't think that the "cooling" effect is solely due to forced perspiration by wind.
The video’s show, a drop from about 45 C to 40 C, which I think is an accurate report. However, they don’t show that the drop is greater than it would be if an opening were made with a panel that blocked as much light and admitted as much airflow as the Eco-Cooler, without using funnels to increase the speed of the air. If they did, I believe the same change in thermometer reading would occur, but the panel would not be as easy to build, nor as be enjoyed as much by the people inside.
The supporters of the gadget state that the cooling is similar to, when blowing onto your hand with a widely open mouth, and then continuing but slowly closing your mouth, the temperature felt goes from warm to cool.
I think this explanation is wrong.
The reason your hand feels, and actually is, warmer, when you blow on it with a wide open vs partially closed mouth is due to entrainment, where the stream of about 37 C air from your mouth drags surrounding room temperature (standard room temperature is 25 C) air with it. This NakedScientist page
has a good description of this.
In air that’s warmer than your breath, like the 45 C air mentioned in the videos, the effect would be the reverse of in standard 25%, your hand feeling warmer when blown on with pursed your lips than open mouth. Notice that in the videos, they do the blowing demonstration outside, where the air is presumably cooler than inside a hot steel-walled shack.
It would be fun to confirm this hypothesis experimentally. If I get a chance, I’ll try using a portable heater to heat a small isolated room in my house to 38+ C, and give it a try.
Also, if you measure the pressure in a venturi system (which the gadget is) 1 in the wider portion, and 2 in the narrower portion, the relatively large difference in pressures has the effect of lowering the temperature in the narrower portion (inside of window);
produces lower air pressure in the narrow part of it where air flows faster. I don’t think, and can’t find anything with a web search suggesting, that this would cause a thermometer in the narrow part of a venturi to show a lower temperature than one in the wide part or outside it. In any case, since the Eco-Cooler venturi is narrow only in the neck of the plastic bottle that passes though the panel, not inside the house, I don’t think the venturi effect has any effect on the house’s inside temperature.
so again the question arises, if there is a cooling inside the room, it must be linked with warming elsewhere, but where?
If, by installing the Eco-Cooler, more air flows through the house than before, and the air outside the house is cooler than air and objects inside the house, then heat is being carried from these warmer surface to the outside by the moving air.
I think the Eco-Cooler works by a combination of increasing total airflow through the house, and reducing the amount heating by sunlight.