What system drains air from outside and delivers fresh air inside?

The natural supply system (NSS) effectively drains air from the outside and delivers fresh air indoors by relying on natural forces like wind and thermal buoyancy. This system does not use mechanical means, making it energy efficient and a more sustainable option for ventilation.

In buildings, the NSS typically works through strategically placed vents that allow external air to enter while displacing stale air, thus enhancing indoor air quality. It allows fresh air to circulate into the space without the use of powered fans, taking advantage of the natural movement of air.

Other options mentioned serve different functions. An air conditioning system primarily cools and dehumidifies indoor air, but it does not specifically focus on bringing fresh outdoor air in. An exhaust system is designed to remove stale or contaminated air from inside a building but does not bring in fresh air. The forced ventilation system utilizes mechanical fans to push air into a space, but its primary role is to circulate air rather than specifically drain outside air and deliver fresh air.