Beyond ‘green’ streets: The role of urban street trees in addressing climate change
Authors: Gallagher, Libby
ABSTRACT: Streets are the single largest public domain resource of our cities, comprising
between approximately 25% to 35% of the total area. Recent debate has focused on transforming
streets to address climate change. A new terminology of ‘green’ or ‘sustainable’ streets has
evolved in city planning and design. Despite the rhetoric, there is a lack of effective tools to
quantify greenhouse gas emissions for the layout structure and components of an existing street,
making it difficult to ascertain just how effective these ‘green’ strategies are.
This paper is a component of a wider study that assesses greenhouse gas emissions associated
with the structure, layout and components of street environments. It provides an overview of the
contribution of urban street trees to this broader research topic. A literature review focuses on two
key areas: (1) the role of urban street trees in carbon storage and sequestration; and (2) the impact
of urban street trees on reducing energy consumption for adjacent buildings through shading. A
methodology is presented for calculating greenhouse gas emissions reductions associated with
urban street trees. Using new technology based on data derived from the local context, it allows
design professionals and government authorities to calculate and test configurations for urban
street trees to optimize reductions in GHG emissions. The methodology will be tested at a later
date in a field study in an existing suburb in north-western Sydney.
Whilst this study focuses on Sydney, the methodology described can be applied to other cities. It
will assist users to cut through the rhetoric of “green” streets and harness new opportunities in
addressing climate change on urban streets.