Begin with a search of the scholarly and trade literature in the Avery Index. From the library website select the "Research by Subject" tab. Choose the Avery Index from the Core Resources section. Enter the term "housing for homeless" in the search box.
Search the library catalog for books. Try terms like "affordable housing" or "homelessness and housing and design."
Websites may be useful too. Try Path: Projects for Assistance in Transition from Homelessness; the KnowledgePlex; and the Public-private Partnership for Advancing Housing Technology Design Professionals.