1. ENRE NEWS ENVIRONMENT, NATURAL RESOURCES & ENERGY
DIVISION {AMERICAN PLANNING ASSOCIATION} | Summer ’15 Issue
5
Local governments around the world are
aiming to significantly reduce or neutralize
their greenhouse gas (GHG) emissions by
mid-century, but until recently, most of the
focus has been on emissions from fuel
combustion, energy, landfills, etc. However,
recent research has shown that, on average,
emissions from purchased goods are by far
the largest source of emissions for public
agencies. Of these purchasing-related
emissions, construction materials such as
cement and asphalt make up the largest
proportion.
To put these emissions in perspective,
the production of cement used in three
large construction projects undertaken
by Seattle Public Utilities (SPU) resulted
in roughly 5,927 metric tonnes of CO2
equivalent (MTCO2e). Considering that
SPU’s recorded emissions from all
sectors in 2009 (purchasing was not
included) was roughly 14,000 MTCO2e,
it should be obvious that these
materials can have a huge impact on a
local government’s emissions profile.
In order to reduce these emissions, local
government officials should look to
techniques from both planning and
engineering. Strategies from planning focus
on reducing the overall amount of concrete
used in city projects through use of green
infrastructure. By incorporating street trees,
bioswales, and landscaping to the maximum
amount possible in city construction projects,
emissions from these materials can be
avoided altogether.
Strategies from engineering focus on
reducing the GHG intensity per unit of
material through use of recycled content,
supplementary cementitious materials such
as fly ash and blast furnace slag, and
technologies that reduce the amount of
energy used in the production process. While
use of these strategies is not feasible in every
case, they do yield a number of co-benefits
and have the potential to reduce emissions
per unit of materials by up to 80%.
Though these planning and engineering
strategies exist and are being used to some
extent for cost and performance reasons,
policy changes are needed to encourage
their aggressive use for emissions reductions.
Potential policy changes include:
• Use incentive specifications that reward
contractors for increased use of low-
GHG engineering technologies;
• Require contractors to complete a
“Carbon Control Plan” in which they
devise strategies to reduce emissions
from materials and fuel use during the
construction process;
• Use alternatives evaluation during the
project design phase.
In order to assist local governments in
reducing these emissions, deliverables for
this thesis include a materials reporting form,
greenhouse gas calculator and alternatives
evaluation table that can be used to analyze
emissions at the project level. By inputting
quantities of materials and usage of GHG-
reducing technologies, project managers can
compare, side-by-side, GHG emissions from
alternative practices. The alternatives
evaluation also gives project managers the
opportunity to see how these practices will
affect the cost of materials.
Local governments are only beginning to
realize the significance of emissions from
construction purchasing. If they choose to
ignore this sector, “carbon neutrality” will be
in name only. Solid strategies do exist to
mitigate these emissions, however, and if
local governments implement them now,
they can stay on track for their mid-century
mitigation goals.
Jacob Tracy was the recipient of the ENRE Division’s
2014/15 graduate student fellowship. Jake recently
graduated University of Washington with a Master of
Urban Planning and is presently finishing up an
internship at Seattle Public Utilities.
Alternatives Evaluation Tool
Demonstration: Below is a demonstration of the
alternatives evaluation tool using a hypothetical
roadway project.
Quantifying (& Reducing) GHG Emissions from Local
Government Cement/Asphalt Purchasing
by Jacob Tracy, 2014/15 Fellowship Recipient