In order to achieve the best visual effect, the directional emphasis of an elevation should be counteracted by the directional emphasis of the openings within it. This means that a horizontally proportioned elevation should contain vertically proportioned window openings, while a vertically proportioned elevation should contain horizontally proportioned window openings. 

A square-proportioned window, though it attracts the eye, is neutral, and imparts no directional emphasis. Square windows may be used on an upper storey above vertically proportioned window openings – the vertically proportioned windows will suffice to balance a horizontally proportioned facade. 

Where a horizontally proportioned window opening is essential, it may be placed in a projecting part of the facade, such as a wing or gable, which has a vertical emphasis that will balance the emphasis of the window. Alternatively, the window may be modified to provide a vertical element.