Sustainability can be significantly influenced by the designs of HVAC systems when they utilize not-so-common technologies, mostly energy-efficient, that drastically reduce for the most part external impacts. They do this by eliminating or converting troublesome substances, for the most part, to harmless forms before their harmful impacts can occur. Sustainability means design systems that eliminate harmful impacts and last a long, long time. Yes, HVAC systems influence sustainability in a significant way when they are designed using common great practices of (1) energy and resource efficiency, (2) using systems with longer lifespans and less maintenance, and (3) design structure that promotes the use of renewable energy sources.