Horse Stable Ventilation

Natural ventilation is used in horse stables and riding arenas. Wind and thermal buoyancy (hot air rises) are the natural forces that drive this type of ventilation (Figure 3). Natural ventilation uses openings located along the sidewall and ridge (roof peak) to accommodate these air movement forces. (Figure 4 shows building terminology used in this publication.) The sidewall openings are more important than the ridge openings if stable design cannot accommodate both sets of openings. The stable ventilation system will work better when both ridge and sidewall openings are provided. The ridge opening allows warm and moist air, which accumulates near the roof peak, to escape. The ridge opening is also a very effective mechanism for wind-driven air exchange since wind moves faster higher off the ground.

Figure 4. Building terminology used for describing ventilation system design and functions.

Go into the horse stall to determine the air quality of the stable.

Wind is the dominant force in horse stable natural ventilation. With the variability in wind speed and direction, openings on the stable will frequently alternate between being an inlet for fresh air and an outlet for stale air. Wind will push air into the stable through openings on the windward side of the building while drawing air out of the stable on the leeward, or downwind, side. Once the wind speed is above about 1 mph, wind-driven ventilation will dissipate the effects of thermal buoyancy in horse stables.

Since horse stables are typically unheated, they are considered "cold" housing. Thermal buoyancy (hot air rises) is dependent upon a temperature difference between the warmer stable interior, where the horses' body heat will slightly warm the surroundings, and the cooler outside conditions. Because a properly ventilated stable has less than a 10°F difference between the stable interior and outside conditions, there is not a large temperature difference as a driving force for buoyant air movement.

What about using fans?

The other major type of ventilation is mechanical ventilation, which uses fans, inlets, and controls in a pressure-controlled structure. Mechanical ventilation is typical in some types of livestock housing (poultry and swine) but is not commonly needed in horse stables. Natural ventilation is adequate for housing animals, such as horses and cattle, that are tolerant of a wide range of temperature conditions. Mechanical ventilation is more expensive to install and maintain but offers control over the air exchange rate. Heated stables may employ mechanical ventilation during the heating season. The fan(s) has a known capacity in cubic feet per minute (cfm) and provides a uniform air exchange rate. Minimum recommendations for each 1,000-pound horse are 25 cfm for moisture control in cold weather; 100 cfm for heat removal during mild weather; or 200 to 350 cfm during hot weather. Inlets are sized at 1.7ft2/1,000 cfm of fan capacity.