Passive ventilation, also called natural ventilation, makes use of natural forces to circulate air to and from an indoor space. It utilizes doors, windows, vents and other openings to bring fresh air into your home without the use of mechanical systems. It’s a strategy window and siding contractors often use to help you reduce your home’s carbon footprint and improve your indoor air quality. If your home is designed for passive ventilation, all you need to do is open or close a window as needed to improve the air you breathe. Here are the basics that you need to know.