Buy your copy of the Barefoot Architect for an amazing read of ideas around rural architecture with natural building materials. A former UN worker and prominent architect, Johan van Lengen has seen firsthand the desperate need for a "greener" approach to housing in impoverished tropical climates.
This comprehensive book clearly explains every aspect of this endeavor, including design (siting, orientation, climate consideration), materials (sisal, cactus, bamboo, earth), and implementation. The author emphasizes throughout the book what is inexpensive and sustainable. Included are sections discussing urban planning, small-scale energy production, cleaning and storing drinking water, and dealing with septic waste, and all information is applied to three distinct tropical regions: humid areas, temporate areas, and desert climates. Hundreds of explanatory drawings by van Lengen allow even novice builders to get started.
Also check out hands-on courses offered by the author and his son at their Eco-School TIBA in Brazil - for more info go to: www.tibario.com