Introduction Even with their winter hair coat, horses are particularly sensitive to drafts and are affected by a number of respiratory ailments resulting from moisture accumulation and foul air. In addition, the respired moisture often condenses on colder building surfaces and accelerates barn deterioration. As the outside temperature warms in the spring and summer, more ventilation is required to remove excess body heat from the horses.
Ventilation uses two physical properties of air to be effective.
First, cold outside air has very little moisture-holding capacity, whereas warm air can hold considerable water vapor. If little or no heating is done, then a large volume of air needs to be exchanged to remove this moisture. Alternatively, a large temperature increase only requires a small quantity of fresh air to control the humidity. Second, warm air is less dense than cold air and is therefore lighter or more buoyant. This principle can work well in natural ventilation systems where the warmer barn air is allowed to rise up and out a peak vent or chimney, carrying the respired moisture with it.