enroof
we think whatever materialistic entity we create today is in the dump yard in our lifespan. hence we propose - DONT BUILD NEW, find ways to make the present usefull, meaningfull, resourcefull.

Solution

we propose to cover the existing dwellings with a roof of plastics(eden garden in britain). embed solar sensors in them - we get power. Collect the water falling over it - we have water for the town, harness the wind energy - we have the extra power. 

While inside even if the house are dirty now - clean them once, paint, you dont have to do it again or atleast 20 years. no mosquitoes, no dust - we have healthy society.
we would save money on cleaning, maintaining, health. consume less energy, less consumables - smaller dump yards.
Basic idea is that each member spend on his own for cleaning, pest control, health etc. But collectively I believe  we would spend lesser and live a better life.
The solution lies in collective design rather than individual designs. 
If 375 billion dollars are available - Do check my guess - We can coverup atleast 50 % of the cities os the world. encompassing about 75% population = without changing their habitat.

Amit