ABSTRACT
ABSTRACT: In cool and cold climates, ventilated roofs do not operate as effectively as they do in the Southern countries. For the detailed analysis of the climate factors’ impact to the air movement in the roof ventilated air gap, the calculation method has been compiled with the corresponding software. The air movement velocity in the ventilated air gap, air temperature alteration at the air outlet vent due to the heat exchange in the gap, indoor air temperature, outdoor air temperature and wind speed, building height and aerodynamic building parameters, dimensions of the ventilated air gap and materials, pressure losses in the ventilated air gap are estimated in the suggested calculation method. The main problems of functioning of the ventilated roofs are faced with during the cold periods of the year. At this time, the temperature of roof hydro-cover is close to the outdoor temperature in conditions of the cold and cool climate. Then the pressure difference necessary to cause the air movement in the ventilated air gap depend only on the wind pressure. In this case the temperature impact is quite low. The dimensions of the ventilated air gap necessary to ensure the functioning of the ventilated roof depend on the dominant wind speed in the location and the constructional singularities of the air gap itself. The worst situation is found in the ventilated roofs of timber construction, when the hydro-protective cover is installed on the timber purlins. The high air pressure losses are caused by the big amount of the purlins
1 DESCRIPTION
Roofs of all inclines with constantly ventilated air gap are attributed to ventilated roofs. Ventilated roofs are designed to allow air to flow through the roof cavity (the space above the insulation) to remove moist air that migrates into that space. Roofs of this type are widely used in dwelling and industrial buildings.
