Clean water, sanitation, and shelter are human rights that also rank as necessities, along with clean air, food, and the freedom to enjoy social interaction with fellow humans. This solution is applied economics with immediate yields that extend beyond quantitative economic analysis to the realm of qualitative profits.
The five-dollar-per-square-foot house, the flycatcher compost toilet, and the potable water storage tank that collects rainwater from its own roof as well as the shelter roof are developed at the ferrocement.com research and testing area and are quickly presented on the web so that the structural and construction techniques are in the public domain and available for use by all who might wish to do so.
Links below the photo of the $5 per square foot shelter, at about $3 per square foot completion, provide access to further details and the production models suitable for billions of people who are in the $2 per day income range.
http://www.ferrocement.com/Shelter-2010/post-1_5-2010.html ... shelter 2010
http://www.ferrocement.com/Shelter-2009/5-22-09.html ... Shelter-2009
http://www.ferrocement.com/tankBook/ch14.en.html ... rainwater
http://www.ferrocement.com/Compost_Toilet/compost-toilet-elements.en.html ... Compost toilet elements
http://ferrocement.com/Compost_Toilet/compost-toilet-2010.en.html ... Compost toilet production feasibility test