Even Passivhaus windows have about eight times the heat loss of a wall but this is partly offset by solar gains. In practice, east and west glazing has much more solar gain than typical south glazing during summer but is difficult to shade. Conversely, simple overhangs from roof and reveals provide shading of the south from the high summer sun.
Because of the net winter gain and relative ease in controlling summer gains, domestic Passivhaus buildings are best designed with as much of the living areas located on the south as possible. This allows the building to be day-lit and ventilated with mostly south glazing.
If we follow this pattern, the south windows would tend to be larger and the others smaller. This further alters the balance in favour of south glazing, as the amount of frame is less in proportion to glass for larger panes.