In the context of the Growth Plan's "complete communities" policies and minimum density target for greenfield development, this section considers the densities that might be achieved in greenfield districts under different development scenarios. A "sketch" model was devised that produces a simulation, a representation of how land uses, people, dwelling units, and jobs are apportioned on a given quantity of land under a defined scenario -- that is, a bundle of inputs specifying how development will occur.
This apportioning is statistical rather than spatial. Although the model determines what proportion of the land area will be taken up by a given land use, it does not indicate where particular activities would be located within the district or how they would be configured or designed. By using proportions and averages, the model cannot take into account such factors as design, proximity of uses, connectivity of street systems, or catchment and market areas for public facilities and businesses, all of which affect the way people use and travel through space. In the real world, of course, location and design matter. Working at this level of abstraction, however, illustrates what densities can be achieved over a district without allocating land uses spatially in a site plan.
The model also does not and cannot anticipate long-term policy, infrastructure investment, and demographic change, including immigration. Policies and government resources may change in the future, as may economic factors such as the price of gasoline, each of which could have a profound impact on land development practices and consumer demand for housing.
As it "builds out" hypothetical districts, the model does not comprehensively account for or presume the prior existence of infrastructure or idiosyncratic land uses that are typically "swallowed" up in outward urban development. The model accounts for two land uses that antedate build-out: natural heritage features and transportation corridors. In the real world, rural cemeteries, golf courses, and resource extraction areas lie in the path of urban expansion, all of which are integrated into local planning.
The purpose of a "sketch model" operating at this level of abstraction is not to make definitive claims about whether the Growth Plan's minimum density target for the designated greenfield area of upper- and single-tier municipalities can be reached, or whether such performance will bring about the Growth Plan's goals. Rather, it is to provide a sense of what interventions are likely to produce greater or lesser changes to density. Ultimately, the absolute density values in the "Baseline" scenario are less important than the relative changes in density produced under the various scenarios. These give an idea of the magnitude of change that might be achieved by increasing or decreasing particular variables, regardless of the baseline value.
The model's inputs and operation, as well as the scenarios tested, are described in general terms in Sections 3.2 and 3.3. Appendix C comprehensively describes all assumptions and data sources employed. Section 3.4 describes the outcomes of the modelling exercise and their implications for planning policy.