During our travels we stumbled upon a sustainable ventilation system which is easy to install. Maresisas Hostel in São Sebastião has installed four exhaust wind fans (so called Exhaust Eólico) in one of their buildings. The fans start spinning by absorbing the hot air from inside the room, bringing in new cool air from outside (See photo below.) The fan doesn’t use any electricity and can replace the need of air conditioners in common areas. This can save you a lot of money in the long run.
It is also possible to connect the fan to an electrical grid for it to gather electricity from the wind, while it is improving your indoor air quality all at the same time. The concept of producing renewable energy while substituting air conditioners (and the high electrical consumption associated with it) just seems awesome!