I think a rent cap could be a good way. It could be raised wrt to inflation. Then, government housing, better loan systems for non profit and maximize density to allow building taller rather than wider (making land cost minimal), but not tall enough that would create increased cost (elevators are expensive to maintain for example). A lot of initiatives need to be put in place, but one that could be effective is to lower costs of construction and find ways to increase productivity by improving resource management