There should be convenient access from feed storage to the barn and from the barn to exercise and training areas. Many traditional designs and techniques have stood the test of time but new materials and innovations are worth considering. In warm climates, an inside aisle isn't essential, so many southern barns are simply single rows of stalls which open to outside pens or runs. Cold climates require inside access to the stalls. A very simple and popular style consists of two rows of stalls which face each other and are separated by an inside aisle.
Closed barns are either uninsulated, insulated, or insulated and heated.
Heated barns are expensive and an unnatural environment for horses and tend to result in more respiratory illnesses. Insulation prevents condensation by keeping the temperature of the interior walls the same as the air inside the structure. The overall shape of your barn is usually decided by the roof type and whether you plan to have a loft in your barn. Storing hay or bedding in a loft over the stalls does provide some insulation for cold climates but is such a potential fire hazard that it is strongly recommended to locate your hay storage in a building separate from the stable. The gable roof is very popular and allows great flexibility in layout.