Build.it has made a mistake typical of this generation of builders: ignorance of Canada's history and particularly its natural history.
As a teenager, I used to design fantasy city plans around towns I knew about, or rather thought I knew about. Eg. Stratford, Owen Sound, and yep, Orangeville!
For years I thought my ideas were the best!
Then during the last 10 years I actually explored these cities, street by street, concession by concession, walked the downtowns, the green spaces and rail trails. Met the farmers, walked into churches.
Holy $%!+ I realized I was a damn fool.
Should we build on the green belt?
Yes, but only if we build it like they did before the 1890s: we will not remove the topsoil, bulldoze nature. Essentially we recreate colonial era buildings using similar construction techniques that result in charming natural low density neighborhoods. Planners, builders, bureaucrats of today can not be trusted! Thus until society has advanced beyond "paint it grey because it's cheap" aesthetic stop building!
Canadian builders are ruining Canada's unique natural environment, causing irreplaceable effects. They're treating the land like an open pit mine, or clear cutting forestry. A better approach would be redevelopment of entire postwar neighborhoods excluding the trees and road infrastructure. Much of Mississauga and Brampton could be rebuilt with stacked townhouses along the crescents and cul de sacs, resulting in at minimum tripled population but with potential for 10X. All with local/Canadian sourced wood and brick construction, possibly reusing the old brick.
Imagine this neighborhood between Dundas and Burnhamthorpe east of the Credit River in Mississauga rebuilt with either dense row houses or stacked townhouses or even two or three storey walk up apartments, filling in the wasted space between these bungalows while keeping the attractive landscaping and over built road infrastructure in place:
https://imgur.com/a/7P7UYzN
Relatively affordable land to assemble, and ideally individual homeowners could rebuild using a city provided template design.
The population could easily quadruple with little impact on road congestion if concurrently, Dundas and Burnhamthorpe were intensified, replacing strip plazas with six storey flats above commercial, LRT running from Toronto to UTM along Dundas and Burnhamthorpe, more frequent bus service throughout the densified crescents etc. Start with the area between the Credit River and Etobicoke Creek, Dundas & Burnhamthorpe Road: 60 years from now the population could be 1 million, a proper city within a city filled with vibrant pedestrian/commercial streets, mature shady streets, beautiful greenspace etc .. or we could destroy thousands of acres of precious green belt.