Farm structures have changed considerably in the past decades and most modern barns and equipment storage buildings are now constructed of wood or steel supports and rafters or trusses, gambrel or peaked roofs, concrete floors and curtain sides that may be opened to maximize airflow in summer. Ventilation is usually facilitated by fans. Barns used for diary needs are designed in accordance with the feed system, food storage and transport, bedding comfort, air quality, good traction and even the amount of heat that cows produce. All a far cry from the old wooden structures that we still see in many country areas.