Build earthen structures using mud bricks and fired mud shingles. This would basically negate almost all of the cost of building materials and only require a place to build and people to build. This could be taken even farther adding recycled plastic bottles filled with sand which adds a lot of benificial attributes and stops plastic building up indefinitely. London and all of Canada is honestly in dire need of "geared to income" housing (1-5 years wait bachelor up to 10 years for a 1-5 bedroom apartment), the jobs created building the structures would be a great thing for all, the buildings would be a great example of sustainability, a lowered carbon footprint, recycling, forward thinking and hopefully it would inspire other communities to start thinking about sustainablity and improving the lives of those who could use it most. If we started building this new community, to solve an age old problem London could grow, evolve, and inspire others to follow our lead toward a green progressive future.