sun when in closed condition there are two inclined fixed casings whose planes cross each other along a straight line which serves as pivoting axis for a window frame in the closed state of the frame in the first casing the frame is parallel to the rays of the sun on fht day of the summer solstice and in the second casing it is perpendicular to the rays on the day of the winter solstice application_number US 19335480 A description in this case the window according to the invention indicated in its entirety by numeral 1 is incorporated in an outer wall 2 of a building which need not be described the actual window 1 is associated with a lower solar collector 3 and an upper solar collector 4 this however is not imperative the window according to the invention can be placed directly and exactly into an opening provided in the wall 2 the window 1 comprises two casings 5a 5b each of which is fixed in a given position the casing 5a is inclined in such a way that it is in a plane which is perpendicular or at least substantially perpendicular to the direction indicated by the arrow sh of the sun rays from the zenith on the day of the winter solstice the casing 5b is inclined in such a way that it is in a plane which is parallel or at least substantially parallel to the direction indicated by the arrow se of the sun rays from the zenith on the day of the summer solstice for fitting the windows into the walls the two casings 5a 5b are at their outer perimeter united by the closing parts which are the upper part 6 the lower part 7 and the.