To begin, a Baseline scenario was created that assumes that:

  • the housing type mix will remain the same as reported for the 1998-2003 period for the GTA excluding the City of Toronto;
  • current standards for the protection of environmentally sensitive lands and public facilities in municipal plans and provincial legislation remain in effect;
  • the amount and type of employment and employment land is consistent with that observed in areas developed since 1980 in Section 2.

Seven additional scenarios were tested, each one altering one or more of the variables in the Baseline scenario, while keeping the others the same.

The first two scenarios tested the effect on density of changes in housing type mix:

  • The Forecast Mix scenario assumes the housing type mix contained in the Ontario government-commissioned Growth Outlook's "Compact" forecast (Hemson 2005), which is incorporated into Schedule 3 of the Growth Plan (MPIR 2006a).
  • The Market Shift scenario assumes that due to constraints on supply, land becomes more expensive, leading people to purchase housing in denser developments. It is therefore assumed that the housing type mix will reflect the Growth Outlook's "More Compact" forecast (Hemson 2005).

A second group of scenarios tested the impact on density of standards for public facilities:

  • The Green scenario assumes that standards for protection of natural heritage features will be increased, reducing the amount of developable land by 20%.
  • The Consolidated scenario assumes that standards for public facilities will be reduced, due to dual-use facilities or the integration of parkland with undevelopable natural heritage or hazard lands. Relative to the Baseline scenario, land allocation for parks and schoolyards decreases by 20% and the proportion of the developable area accounted for by rights-of-way decreases from 26% to 20%.

A third group of scenarios tested the impact of greater mixed-use development:

  • The Mixed-Use scenario assumes that higher land prices and policy changes will compel modest changes in employment location. A portion of office employment in business parks will relocate to higher-density, free-standing office buildings. Some retail jobs will move from "big-box" power centres and shopping malls to mixed-use locations embedded in the residential urban fabric. The remaining industrial and commercial jobs on employment lands will be built 25% more densely.
  • The Jobs-Housing Balance scenario assumes that the amount of employment land is increased to accommodate one job for every member of the resident population participating in the labour force.

A final scenario combines many of the elements of the other scenarios. It represents what might be possible if many changes occurred simultaneously:

  • The Big Moves scenario combines the Market Shift, Consolidated, and Mixed-Use scenarios.

Each scenario is applied to three hypothetical pieces of land, each representing a different degree of natural heritage protection. The distinction between natural heritage features and systems is illustrated in Fig. 52.

  • In the Low case, natural heritage features cover 5% of the gross land area. After applying buffer zones and habitat connections, the natural heritage system comprises 10% of the gross land area.
  • In the Medium case, natural heritage features cover 16% of the gross land area and the natural heritage system 29%.
  • In the High case, natural heritage features cover 27% of the gross land area and the natural heritage system 39%.

The combination of the eight development scenarios and the three levels of natural heritage protection leads to 24 combinations.

Appendix C explains the input assumptions to the scenarios and the background research on which they are based.

The spreadsheets used to calculate the scenario's outputs are available on the Neptis Foundation's website at <>. The researchers invite readers to comment on, experiment with, modify, and refine the model and its inputs, and to share the results.