Residential intensification--moving the focus of new residential development from peripheral farmland to existing built places--is a key element in most growth management efforts.
Although intensification is a commonly used term, its meaning is not fixed.3 Appendix A provides some examples of different approaches to defining and measuring intensification from British Columbia, the United Kingdom, and Australia. Some jurisdictions use the term to refer to all high-density development, no matter where it occurs.4 Others define it as construction on previously developed land.5 Still others consider any new residential development within the existing built-up urban fabric to be intensification.6 By this definition, intensification may occur on undeveloped or on previously developed land; what makes it intensification is its location within the area defined as already urbanized. This third definition is the one used by the Ontario government.
Intensification is promoted as a way to achieve several benefits. First, if population growth can be accommodated at higher densities, or within existing urban areas, or both, less greenfield land will be required for new housing.7 Second, research shows that when density increases beyond a certain level, automobile use declines in favour of transit, walking, and cycling.8 Third, where surplus infrastructure capacity exists in urbanized areas, adding more people to these areas makes more efficient use of public urban infrastructure such as water and sewer pipes, as well as "soft" infrastructure such as public schools and social services.9 In short, development in already urbanized areas plays to the city's strengths rather than spreading its resources over an ever-wider territory.
3. The lack of a clear, agreed-upon definition for the word "intensification" was explored in P. Campsie, The Social Consequences of Planning Talk: A Case Study in Urban Intensification (Toronto: Centre for Urban and Community Studies, 1995), Research Paper 190.
4. See Regional Municipality of York. York Region: Residential Intensification Study (20 August 2004).
5. Ministry of Communities and Local Government, Planning Policy Guidance 3: Housing (London: HMSO, 2000; updated 2005).
6. The definition of intensification in the glossary of the Growth Plan for the Greater Golden Horseshoe is the same as in the Provincial Policy statement, Section 6: "the development of a property, site or area at a higher density than currently exists through (a) redevelopment, including the reuse of brownfield sites; (b) the development of vacant and/or underutilized lots within previously developed areas; (c) infill development; and (d) the expansion or conversion of existing buildings." However, the way in which the intensification target is set implies that intensification is any growth "within the built-up area" of a municipality.
7. IBI Group. Urban Travel and Sustainable Development: The Canadian Experience (Ottawa: CMHC, 1993); P. Blais. Inching Toward Sustainability: The Evolving Urban Structure of the GTA (Toronto: Neptis Foundation, 2000) 37.
8. See, for example, E. Miller and A. Shalaby, Travel in the Greater Toronto Area: Past and Current Behaviour and Relation to Urban Form(Toronto: Neptis Foundation, 2000); R. Cervero, The Transit Metropolis: A Global Inquiry (Washington, D.C.: Island Press, 1998) ch. 3; P. Newman and J. Kenworthy, Sustainability and Cities: Overcoming Automobile Dependence (Washington, D.C.: Island Press, 1999) ch. 3; B. S. Pushkarev and J. M. Zupan, Public Transportation and Land Use Policy (Bloomington: Indiana University Press, 1977) ch. 2.
9. See, for example, P. Blais, The Growth Opportunity: Leveraging New Growth to Maximise Benefits in the Central Ontario Zone. Issue Paper No. 5 (Toronto: Neptis Foundation, 2003); P. Blais, The Economics of Urban Form(Toronto: Berridge Lewinberg Greenberg Dark Gabor, 1995) 9-18; IBI Group,Greater Toronto Region Urban Concepts Study (Toronto: Office of the Greater Toronto Area, 1990); IBI Group, GTA Urban Structure Concepts Study Revisited: Broad Revision of Selected Cost Estimates (Toronto: GTA Task Force, 1995); C. A. De Sousa, "Measuring the public costs and benefits of brownfield development versus greenfield development in the Greater Toronto Area," Environment and Planning B: Planning and Design 29 (2002) 251-80; Real Estate Research Corporation, The Costs of Sprawl: Environmental and Economic Costs of Alternative Residential Development Patterns at the Urban Fringe (Washington, DC: US Environmental Protection Agency, 1974); R. Burchell et al., The Costs of Sprawl--Revisited, prepared for the Transport Research Board (Washington: National Academy Press, 1998); CMHC, Conventional and Alternative Development Patterns--Phase I: Infrastructure Costs, prepared by Essiambre-Phillips-Desjardins Associates (Ottawa: CMHC, 1997); J. I. Carruthers and G. F. Ulfarsson, "Urban sprawl and the cost of public services," Environment and Planning B: Planning and Design 30 (2003) 503-522.