GIZ (former GTZ) Proklima has compiled this publication to provide information on natural foam blowing agents as ozone- and climate-friendly alternatives to HCFCs. The first section of the book covers policy-related aspects of technology transition towards natural foam blowing agents and examines the impact legislative changes have on development and adoption of alternative technologies. The second part deals with the use of natural blowing agents in rigid and XPS foam, the conditions for conversion and special technologies. Part 3 comprises case studies from developing countries.