Density 101

February 1, 2018

What is density?

Density is often misunderstood. Density in the context of urban planning and design has a number of different definitions and considerations, including residential density, site density and site coverage.

Well designed, compact infill in cities and communities is fundamental to “smart growth.” Smart growth is an approach to development that encourages a mix of building types and uses, diverse housing and transportation options, development within existing neighborhoods, and community engagement. It contains 10 principles including: creating a range of housing opportunities and choices; taking advantage of compact design, and; making development decisions predictable, fair and cost effective.

Planning addresses the use of land, resources, facilities and services in ways that secure the physical, economic and social efficiency, and the health and well-being of urban and rural communities.

Urban design considers the arrangement of buildings, streets and public spaces, neighborhoods and districts, with the aim of making these areas functional, attractive, and sustainable. It plays an important role in maintaining and enhancing the quality of life in Canadian cities. High-quality urban design comes from the expertise of planners, architects and landscape architects.

Residential density typically refers to the number of people inhabiting a given urbanized area. For example, the number of people residing or working in a particular area, such as 95 people per square hectare.

Site density typically refers to the total floor area of all buildings on a lot divided by the lot area.  It is commonly measured using “floor space ratio” (FSR) — in other words, the  ratio of floor area to land area.

Site coverage typically refers to the footprint that all buildings and structures make on a site (e.g. the area occupied by the building or proportion of land covered by buildings). A building may be very tall with a small footprint (high-rise low coverage) or a building may be only one storey but cover the entire site area (low-rise high coverage).

How is density used in urban planning?

Density is a quantitative measure, (e.g. number of people or buildings per hectare, floor space ratios, footprints of buildings etc.) commonly used in land use planning because it is simple to calculate and express.

Density does not capture more qualitative characteristics typically associated with urban planning and design such as siting, scale and articulation of buildings, open/green space, pedestrian-friendly access, and transportation. Urban design is about place making within a local to regional to global context. It’s how buildings, streets and open spaces work together to create a sense of place. Varying density within a neighbourhood provides for a diversity of housing opportunities for residents.

How does density relate to urban sustainability?

By strategically increasing residential density, urban areas not only go a long way toward meeting their sustainability objectives, but also ensure they are competitive, resilient and great places to live.

When used properly, density is an important part of what makes cities environmentally, economically and socio-culturally sustainable. This includes more efficient delivery of public services and infrastructure, lower environmental impact, and safer, more dynamic urban districts. It also provides for more socio-cultural diversity.

Why are some people opposed to density?

When faced with the prospect of an affordable housing development in their neighbourhood, some people are contradictory in their support – stating they are in favour of affordable housing, but prefer the status quo when it comes to their own neighbourhood. They are sometimes referred to as NIMBY (Not In My Backyard). The NIMBY perspective is often rooted in a perceived conflict between the proposed development and the impact it will have on the lifestyle and investment of existing residents.

When it comes to density specifically, most often residents are concerned about increased traffic, street congestion and strain on urban infrastructure.

While loving the current status of a neighbourhood is worthy, the reality is neighbourhoods and communities change over time. What worked 10, 30 or 50 years ago in urban planning will not adequately address the community challenges of today, particularly not with climate change, cultural diversity and infrastructure deficits.

Urban planning has made many advances in planning practice to properly regulate and incent densification. The key question in urban planning discussions is not whether urban areas ought to become denser; it will be how to best manage it.