• Green Neighborhoods
  • Learn
  • Plan
  • Act
    • Leading Actions
    • Characteristics
      • Location
      • Density and Mixed-Use
      • Pedestrian Environment
      • Cycling Environment
      • Support for Transit
      • Parking Management
      • Transportation Management
      • Green Networks
    • Policy Levers
Density and Mixed-Use
Compact and mixed-use neighborhood design is essential to reducing greenhouse gas emissions.
Crossings at Gresham Station, a high-density Transit-Oriented Development in Gresham, Oregon. Photo Credit: Myhre Group Architects

In many places, overcoming public perception of negative implications of density is the most critical aspect of supporting green neighborhoods.  To do so, it helps to highlight the benefits and share supporting statistics and concrete examples. The following details may be useful.

What is Mixed Use? 

Mixing uses means allowing shops, services, amenities, jobs and homes to be located within easy reach of one another, often on the same parcel and in the same building.

Benefits:

  • Community building: The opposite of single-use zoning, it helps minimize the need for automobile travel and creates a more vibrant community. 
  • Energy use: Mixed-use areas are excellent opportunities for district energy systems (where a central plant supplies heating and cooling to groups of buildings). Businesses and residences tend to need these services at different times, which maximizes efficiency of the systems and making for an attractive business case in many instances.

Conisiderations:

  • Business impacts: To smooth the transition of a neighborhood from single-use to mixed-use, local government may need to manage business impacts on residential areas by limiting hours when noisy activities can occur, controlling access to parking, or other measures.
  • Affordable housing: To maximize reductions in greenhouse gas emissions, planners should evaluate whether people who work within walking distance or good transit destinations will be able to afford the housing that will be built. If not, it’s worth exploring whether incentives, regulation changes, or other measures would support an optimum match.

Many municipalities are making progress in this area, enabling and encouraging mixed-use areas.  For example, Seattle recently developed  the “Seattle Mixed Zone” to encourage mixed-use development in urban centers.

 What is "Compact"?

While density is important to support local stores, make district-energy systems feasible and ensure that public spaces are well used, density targets are often defined by thresholds where there are enough residents to support different levels of transit service:

Transit service levels:

  • At 4 to 8 units per acre, buses can run every 30 minutes.
  • 15 or more units per acre, buses can run more frequently, which typically attracts more riders.

The threshold of 15 units per acre is a minimum target for any transit-oriented development. It’s also a useful target for average densities within walking distance of existing and potential bus routes.