Effective ventilation system

For some reason, during the construction of a private house most often, instead of a full-fledged ventilation system, air conditioners are installed. Of course, to cool the air with a hot summer day — this is important, but the purity of air in this case is not guaranteed. The air conditioner only drives the same air masses, while usually does not take fresh air from the street. Therefore, freshness here “does not smell”, only with coolness.