A window structure is configured to form a principal chamber enclosing a first window pane installed in an exterior wall of a building. The window structure includes a first surface configured to absorb solar energy and a main frame including a second window pane. An axial hinge is configured to allow to the main frame to tilt between a first position and a second position. When the main frame is tilted in the first position, the first surface is positioned in a first orientation that allows the first surface to directly receive sunlight through the second window pane. When the main frame is tilted in the second position, the first surface is positioned in a second orientation in which the first surface is prevented from directly receiving sunlight through the second window pane. The window structure may be used for ventilating the structure and shading during the warm weather.