Density - Comparing Apples to Apples

"It's really important to know what density calculations we are comparing and be sure to compare apples to apples."

Density can be calculated in different ways. Some calculations of density produced by Stats Canada are by neighbourhood and include roads and parks. Roads take up about 40% of a typical neighbourhood block. So it's really important to know what density calculations we are comparing and be sure to compare apples to apples. The draft Official Plan is out and it proposed lots of minimum residential densities, but what do those density numbers mean? For example, how should we understand a minimum requirement of 80 DUs/hectare? For starters, DUs refers to Dwelling Units. This can be a single home that houses a family of 5, or an apartment that houses 2 people.

The simplest way of understanding the Draft Official Plan density targets is as follows: in the Transforming Overlay (generally older neighbourhoods) new development (i.e. infill) would need to match the density of a standard sized semi with secondary dwelling units (i.e. 4 dwelling units in total) on a 50'x100' lot. In the Evolving Overlay (generally inner urban bungalow neighbourhoods) it would be the same semi but without the secondary dwelling units (i.e. 2 dwelling units).


But the Draft Official Plan indicates that Ottawa is moving toward 'Form-Based-Zoning', and that means letting go of definitions of "semis" and "secondary dwelling units", and that opens up all sorts of new options that might fit better in our neighbourhoods than the example above.

"...this solution is easy, lovely, simple... - an opportunity to breath new vitality into our neighbourhoods, allowing existing residents the benefits of density: regeneration and walkability."

This building (on a lot size of 33'x100') could contain 1 very large dwelling or 6 one bedroom units. Or it could contain any combination of units of varying size, all with their own entrance door. If it contains 1 home, this is a density of 35du/ha (dwelling units / hectare) If it contains 6 units this is a density of 215du/ha. But it could be designed to look generally like the same building on the outside - certainly to respect the same setback requirements as existing.


There are already lots of examples of this in our more mature neighbourhoods - picture a big older home in the Glebe, for example, that was reconfigured into a large, ground floor apartment suitable for a family, a couple of apartments for 2 people above, and single apartments in both the basement and 3rd floor. And yet from the outside, the house looks much like it did when it was first built, except some additional entrances have been added.

"Multi-unit buildings sized and spaced to 'fit-in' on our neighbourhood streets -- this is what 'gentle density' should look like in Ottawa."

These days, half of our households in Ottawa are 1 or 2 person households. Since the 1950's the amount of living space per person has increased by 5 times! Our neighbourhood housing is predominantly larger units, rather than a diversity of units that reflects our diverse households (singles, couples, families, multi-generational, etc.). This kind of multi-unit infill would generate balance and diversity, and is made possible by "Form-Based-Zoning". Unfortunately, the Draft Official Plan also includes barriers to prevent this kind of development, and even specifically envisions smaller households and seniors to be housed on busy streets bounding neighbourhoods rather than on quiet community streets.


Multi-unit buildings sized and spaced to 'fit-in' on our neighbourhood streets -- this is what 'gentle density' should look like in Ottawa. This approach to new infill makes density targets easily achievable, and rather irrelevant. But this simple solution only works in the context of walkable neighbourhoods, because our communities would have to be paved over and treeless if each new household required a parking space or two. In the context of a walkable neighbourhood, this solution is easy, lovely, simple. And it's an opportunity to breath new vitality into our neighbourhoods, allowing existing residents the benefits of density: regeneration and walkability.