Terwilliger retired last year from Trammell Crow Residential after nearly 30 years with the Atlanta-based company but remains its chairman. He currently chairs Habitat's board of directors, of which he has been a member since 2000.

"In my professional life, I've seen housing strengthen health, education, families, communities and economies," Terwilliger stated in a release. "With this legacy gift to Habitat for Humanity, I want to help ensure a leveraged, sustained impact beyond my lifetime and inspire others to make the commitment to support affordable housing."

Within five years of the funds being transferred by Terwilliger's estate, 70% of the legacy commitment will be used by Habitat for housing microfinancing so that families around the world can improve their living conditions. The remaining 30% will be used for a "leveraged impact fund" that will make annual distributions to help support affordable-housing efforts.