Stable Design
by Susan Raymond of the Equine Research Centre, Guelph, Ontario

Ventilation

The ideal ventilation system

	provides fresh air without drafts during all seasons
	distributes air uniformly
	will help minimise your horse's exposure to a wide range of environmental irritants
	if natural ventilation is not sufficient, mechanical can be used

Natural Ventilation

Air moves by one of three ways (or a combination of the three):

1. The "stack effect" or thermal buoyancy:

	air movement is driven by temperature differences
	cooler air enters the barn through lower openings (inlets)
	air is then mixed with warmer air that is inside the barn (usually this air has been warmed by heat coming from the horses or by activities in the barn)
	warm air rises and exists the barn from higher openings (outlets)
	displacement of air causes more air to be drawn into the inlets

2. Aspiration

	air is moved by the action of the wind blowing across the roof of the barn
	this action draws air out through any available opening

3. Perflatation

	wind is blown through openings in the barn
	air is moved from side to side or from end to end

Ways to achieve a well ventilated barn

	in warmer weather, windows and doors are usually open
	permanent openings should be installed to achieve sufficient air changes when windows and doors are closed
	the greater the height difference between inlets and outlets the greater the ventilation rate

Inlets

	installed along each long side of your barn
	hinged on the inside bottom side of the vent (will help avoid drafts)
	baffled vents will help prevent drafts and the entry of snow or rain
	place as low as possible but not at a height that could interfere with your horse
	should be adjustable

Outlets

	continuous ridge along the peak of your roof or chimney(s)
	should be capped to prevent water from entering
	a copula on the chimney will prevent water from entering
	if the barn has a loft make sure that there are openings in the floor of the loft to allow air to reach the outlets at roof level
	or extend an insulated chimney down through the loft to the stable ceiling
	rule of thumb - install inlets twice the area as outlets
	if using a mechanical system, install an extractor fan in the base of the chimney
	the recommended pitch in the roof is 1:2 with a roof overhang of 2-3 ft

Insulation
Important for all seasons

Winter
conserves heat and reduces condensation

Summer
prevents heat of sun from heating barn

Spring and Fall
minimises temperature fluctuations caused by warm days and cold nights

Ventilation and insulation work together

	during the winter ventilation is usually greatly reduced to keep the barn warm
	if the reduced ventilation does not remove the moisture produced by the horses the result will be a cold, clammy, damp barn with condensation problems
	if the barn is insulated and not properly ventilated it will be even worse
	condensation occurs when warm stable air hits a cold inside wall

Installation

	the vents in an insulated barn can be smaller than in a non-insulated barn
	a vapour barrier on the inside wall will help prevent condensation within the insulation
	the more porous an insulating material is, the greater is its insulating power
	if you are limited in what you can do, insulate the roof first

Heat (usually not necessary)

	could prove useful if your barn is still cold and damp in the winter
	it is better to add supplemental heat than reduce ventilation
	a number of infrared heaters are suitable for barns

The Checklist

	Your Dimension	Recommendation
Stall Size		12 × 12ft (3.6 × 3.6m)
Stall Door Width		4 ft (1.2m)
Stall Door Height		8ft (2.4m)
Stall Ceiling Height		12ft (3.66m)
Floor Area Per Horse		150ft2 (14m2)
Airspace Per Horse		1553ft3 (44m3)
Outlet Area Per Horse*		1.08ft2 (0.1m2)**
Inlet Area Per Horse		3.23ft2 (0.3m2)
Humidity Range		30% - 70%
Temperature Range		0 - 30°C (32 - 85°F)

*note: an insulated stable can have slightly smaller inlets and outlets

**note: may only be suitable for smaller buildings - may be more appropriate for medium and larger buildings: general rule of thumb: 1 to 1.5% of floor area = area required for an open ridge ventilator.

How to measure your barn

Floor area per horse:

length of barn × width of barn
# of horses

Airspace per horse:
If the barn has a closed loft:
length of barn × width of barn × height of barn
# of horses

If the barn has an open pitched roof:

	a. volume of barn without roof:
	length of barn × width of barn × height of barn
	b. volume of pitched roof:
	barn length × barn width × height of highest roof point 2
	c. volume of barn:
	answer a + answer b
	d. airspace per horse:
	answer c # of horses

Outlet area per horse:

total area of all chimneys or all outlet vents
# of horses

Inlet area per horse:

total area of all inlet vents or open windows
# of horses