The value of natural light in buildings has only recently gained any kind of mainstream consideration, and most codes have only minimal requirements for glazing area and natural light: many rooms do not even require windows if electric lighting is provided. Given the importance of natural light to our bodies, adequate access to natural light should be part of your design considerations.
Important questions to ask include:
Does every room have at least one window?
Is at least one window visible from all locations in the home?
Are multiple windows visible from all locations in the home?
Is it possible to have at least two windows in each room, preferably on different walls?
Are windows blocked or shaded from the outside?
Are areas that are underserviced by windows naturally lit in other ways?
Have light tubes, light wells, skylights, or other strategies been considered for areas not serviced by windows?
Are natural light patterns considered in the overall design?
Have window locations and room placements been optimized for the timing of activities in the building.