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Analytic Techniques

Mapping LEED ND Sites In and Around Boston

Author: David Scheltz

LEED ND is a recently-released development rating system, published by a coalition of the Congress for the New Urbanism, the US Green Building Council, and the Natural Resources Defense Council. Its overarching goal is similar to LEED, in that it seeks to encourage environmentally sound development. Unlike previous LEED systems, however, LEED ND looks beyond the performance of a building by emphasizing regional and neighborhood-level objectives. Chief among these is to reduce vehicle miles travelled (VMT). Distilling the worthy concept of sustainability into a set of objective measurements,however, is no easy task. Rather than describing myself how the scoring system attempts it, I encourage you to download the document from the USGBC's website.

LEED ND's top priority is encouraging developments that reduce the demand for vehicle travel. The question I pose is: how successful is the system likely to be? A critical first step is actually mapping sites that would be eligible under the LEED ND criteria. I have chosen the Massachusetts Bay area for my analysis. Then we can study the eligible areas and think critically about whether or not development in those locations would generate less vehicle travel and/or promote more walking and transit use, based on what we know of the relationship between travel behavior and the built environment.

There is much more to LEED ND that just the site selection. Most of the system deals urban design and building-level qualities, so this analysis cannot provide the final word on LEED ND's suitability. Still, as my probability professor liked to say, "all models are wrong, some are useful". I hope you will find this model useful, and I encourage you to download it, learn from it, and improve upon it.

Resources

References

Purpose and Question

The purpose of this model is to map sites that meet LEED ND's location prerequisites. Roughly speaking, these require that the site be:

My model consists of 5 tools that attempt to approximate each of these criteria using raster analysis methods.

Exploring the Model

    Open the LEED_ND_GIS folder. You'll see that this folder contains
  1. folders for data sources
  2. folders for the output data that the tools create ("infill_output", "adjacency_output", "transit_proxy_output", "use_output", and "eco_output")
  3. the LEED ND toolbox (a .tbx file)
  4. a .mxd file that brings it all together.

Evaluation

The slideshow below shows the 4 resulting maps for each of the 4 tests, plus the overlaid "environmental criteria" layer.


Parting Thoughts/Areas for Improvement

If you take the time to look through the LEED ND manual, you'll find that the scoring system is very complex. This model only approximates the Smart Location pre-requisites. Here are the areas I see as most important for improvement:

  • Modelling the credit system. By using the Reclassify and Single Output Map Algebra features, you can create raster images that tell you how many points a cell might score under a number of the Smart Location Credit Areas. The result would be a "NEED ND Score Map" rather than just a binary eligibile/not eligible map.
  • Measuring transit level of service. The transit test requires that the transit service in proximity to a site have a certain level of service, but I did not have this data available. Finding it and joining it to the shapefile would improve the accuracy of the model.
  • Expanding the scope of analysis. I only ran the results for the Mass Bay area. This was because running raster tools for large areas takes a long time and I was limited by the extent of the nlcd groundcover layer. Finding a larger layer will allow you to see results for a much larger area, which would be interesting because my extent did not allow me to see outer suburban/exurban areas.