Ventilation vs Weather Protection. Where there is a risk of an explosive cloud forming it is desirable to provide natural ventilation to disperse the cloud. Where leaks can occur the ideal venting would be represented by an open module. However, it can be demonstrated that the environmental conditions on open modules are such that maintenance standards suffer, leading to increased hazard. It is therefore also desirable to partially enclose process areas using weather cladding in order to provide the optimum working environment. The extent of enclosure is a careful compromise between ventilation and internal environment.