A home built in the 1860s uses the principle of the whole house fan, but without the fan: you just open the windows at night and close 'em during the day, and y

A home built in the 1860s uses the principle of the whole house fan, but without the fan: you just open the windows at night and close 'em during the day, and you can regulate more with an attic trap door. It works well most of the time, but sometimes there's problems. Namely, if humidity gets trapped in the house, when you shut the house during the day, it can smell like mildew. It can be near-impossible to remove the humidity from the house without an air conditioner of some sort, or a dehumidifier. An evaporative cooler at night would make this worse because you're adding humidity. Another problem is multiple storeys. The top floor will always be hotter, and it can build during hot days and leech the cool air from below. You need a powerful attic fan to remove excess heat and humidity or the top floor will become a swamp. If you live in a big city, the average ambient temperature during the summer is probably going to be high enough that a whole house fan will not replace air conditioning, but could supplement it.