If your house was built before 1978, it probably contains lead-based paint, the leading cause of lead poisoning in children. Dispose of all construction debris containing lead paint as household hazardous waste at your local solid waste facility. All hired contractors must provide homeowners with a brochure before beginning a window, door, or skylight replacement. View the brochure (3.25 MB).
You don’t want those old windows and doors, but someone might. If they are free of lead paint (3.25 MB), consider donating your windows, doors, and other unwanted building materials to a Building Materials Reuse Center (BMRC). BMRCs have sprung up all over the country to give used, but still useful, building materials a second chance before sending them to a landfill. Check the directory of BMRCs maintained by the Building Material Reuse Association to find a center near you. Call ahead to make sure they accept windows.
Habitat for Humanity has over 500 ReStores nationwide that accept donated building materials. Call ahead to make sure they accept windows, and ask for a receipt so you can write your donation off on your taxes.