There is a long-standing controversy over the basic need for a chicken coop. One philosophy, known as the fresh air school is that chickens are mostly hardy but can be brought low by confinement, poor air quality and darkness, hence the need for a highly ventilated or open-sided coop with conditions more like the outdoors, even in winter.However, others who keep chickens believe they are prone to illness in outdoor weather and need a controlled-environment coop. This has led to two housing designs for chickens: fresh-air houses with wide openings and nothing more than wire mesh between chickens and the weather (even in Northern winters), or closed houses with doors, windows and hatches which can shut off most ventilation