All lawn types need direct sunlight every day in order to survive, there really is no compromise on this fact. By managing shade, choosing the right lawn type and making a few changes to our lawn care practices, we can grow green healthy lawns in partially shaded areas of the yard.
The continuing priority for growing lawns in shaded areas is to continue to manage the shade itself. This usually requires regular pruning of trees, bushes and other foliage to allow as much sunlight into the affected area as possible.
The same shade reducing principle can also continue onto the structures around our homes too. Look at any modifications that can be made to these structures to increase sunlight. This could mean removing temporary structures, moving small garden sheds, and replacing a few sheets of Iron roofing on Pergolas with Clear Plastic roofing alternatives.
This is the most important aspect of managing lawns in shaded areas, A Couch lawn will never tolerate shade of any sort, it will simple wither, become stringy and eventually die. Whereas a Buffalo lawn, or even Kikuyu lawn will tolerate shade much better. If these lawn types aren't to the homeowners liking, then Zoysia does have far better shade tolerance than Couch, but not as good as Buffalo or Kikuyu.
When choosing a new lawn type, plan ahead and look for the future shade tolerance requirement for the new lawn, and choose a lawn type accordingly.
For existing lawns that are struggling, the entire lawn doesn't need to be replaced, planting some new runners of a shade tolerant turf will often suffice for these areas, and will eventually blend into the existing lawn where the shade meets the sun.
The reason lawns don't live well in shade is because they need sunlight to power their photosynthesis process. This happens through the green leaf of the lawn, and the longer the green leaf - the greater the photosynthesis.
Mow lawns longer in shaded areas, this allows the lawn to become far more efficient to convert the available sunlight into photosynthesis. As an example, if we doubled the mowing heights in shaded areas, we have effectively doubled the photosynthesis in this area.
Lawn in shaded areas can often get soggy or water logged, which further exacerbates the problems of growing lawns in shady areas. If this is true for your lawn area then be sure the soil is regularly aerated via lawn coring or using the garden fork method. More information on lawn aeration here.
If a lawns simply will not grow in the affected high shade area regardless of what we do, then sadly the last option to consider would be to remove the lawn, and replace it with a garden bed, pathway, or perhaps even a new garden shed.