The presence of ice crusts and icicles on roofs is an urgent problem since they influence the safety of people and property which are under cornices of roofs. There are a lot of methods to stop icicle formation on the roofs. But most of them are in need of expensive and complex equipment. At present article is used a way of stopping forming ice dams by creating a "cold attic". Tehnique of a transient air hole was offeredto make it. The transient air hole can change its section area depending on wind speed. Such a constriction allows entering into the attic a bigvolume of cold air. Also, it helps to prevent a noise which is provided by a usual air hole. This concept was confirmed by a heat balance of the attic.