An on-site mobile facility for shielding from wind exerting a wind load on the facility, rain or snow when constructing, renovating or assembling a building, a bridge or a wind turbine, the on-site mobile facility covering an area having boundaries and corners, comprising: - a plurality of base structures adapted to be arranged in holes at predetermined locations at the site along the boundaries, - a plurality of legs, one of the legs is fastened to each of the base structures being part of one of the corners, - a plurality of modules, each module having a module roof structure, the module roof structures being mounted as a facility roof structure connecting horizontal beams of the module roof structures, the facility roof structure having edges and the horizontal beams defining the edges which are supported by the legs, the legs and the beams defining side areas, the side areas being covered by a shielding arrangement, characterised in that the shielding arrangement of the side area comprising: - elongated elements, and - cover material, such as tarpaulin, being arranged between the elements and connected therewith, in that the on-site mobile facility further comprises a guide system for guiding the shielding arrangement of the side area, the guide system being slidably connecting the elements with one of the beams or the adjacent legs so as to at least partly uncover the side areas, so that wind is allowed to pass through the facility by passing through the uncovered part of the side area and out through an uncovered part of the side area on another side of the on-site mobile facility to reduce the wind load on the facility in order for the facility to remain unaffected by the wind load during heavy winds, and in that two of said beams are fastened so that a first end of one of the two beams is fastened to a corner block of one of the legs adjacent the leg in one of the corners, and a first end of the other of the two beams is fastened to a corner block of another one of the legs adjacent the leg in that corner, and second ends of the beams are fastened to each other by means of a corner block which is unsupported by a leg, thereby forming a square frame of beams in that corner. - a plurality of base structures adapted to be arranged in holes at predetermined locations at the site along the boundaries, - a plurality of legs, one of the legs is fastened to each of the base structures being part of one of the corners, - a plurality of modules, each module having a module roof structure, the module roof structures being mounted as a facility roof structure connecting horizontal beams of the module roof structures, the facility roof structure having edges and the horizontal beams defining the edges which are supported by the legs, - elongated elements, and - cover material, such as tarpaulin, being arranged between the elements and connected therewith, in that the on-site mobile facility further comprises a guide system for guiding the shielding arrangement of the side area, the guide system being slidably connecting the elements with one of the beams or the adjacent legs so as to at least partly uncover the side areas, so that wind is allowed to pass through the facility by passing through the uncovered part of the side area and out through an uncovered part of the side area on another side of the on-site mobile facility to reduce the wind load on the facility in order for the facility to remain unaffected by the wind load during heavy winds, and in that two of said beams are fastened so that a first end of one of the two beams is fastened to a corner block of one of the legs adjacent the leg in one of the corners, and a first end of the other of the two beams is fastened to a corner block of another one of the legs adjacent the leg in that corner, and second ends of the beams are fastened to each other by means of a corner block which is unsupported by a leg, thereby forming a square frame of beams in that corner.