A5 Construction Phase Emissions

A5 emissions, or construction phase emissions, includes the emissions associated with onsite activities of assembling the building or project including onsite assembly and installation of materials. This includes activities such as temporary electricity, fuel for generators and heavy equipment, fuel for welding, etc. EC3 has an A5 calculator to help users easily convert fuel from these activities into emissions or global warming potential (GWP).

To access the A5 calculator, click on the A5 tab in the building project planner. In the first column, the user can enter a description of the activity such as "Temporary Generators" or "Excavation". In the "Input Type" column, the user will select the appropriate fuel or energy type from the dropdown list of options. The user will then add the quantity and unit of measure for each activity type. The final step is to select the fuel source from the dropdown under the "Source" column. Note that certain input types such as Electricity will have multiple source options, since the emissions intensity of electricity varies by location. The GWP column will automatically populate based on user input in the preceding columns.

EC3 calculates the impact of fuels consumed on the construction site based on user input. The result is then shown as A5 construction impact. This calculation takes into account:

  1. Amount of fuel consumed (manual user entry)

  2. Fuel type (including upstream and combustion impact)

Amount of fuel in EC3 is not explicitly tied to any material quantities tracked in A1-A4 scope. Instead, users are required to manually enter the amount of fuels and resources used during construction based on their own knowledge or data collection. EC3 currently does not provide any default quantity estimates.

Fuel types in EC3 cover the basic fuels and resources used on typical construction sites. The GWP factors provide the amount of kgCO2e emitted per unit of fuel used, including upstream production impacts and direct combustion impacts for the given fuel or resource, unless noted otherwise in the list of fuels and resources for construction. The associated impact factors come from a combination of sources, including regional LCA datasets, such as USLCI in the United States [1]. See details in the linked sheet. It is also possible to enter a custom GWP factor for any fuels and resources not in the default EC3 list.

To calculate the A5 construction impact, we multiply:

GWP_a5 = amount_of_fuel * fuel_type_gwp_intensity

As usual, EC3 handles unit conversions.


[1] National Renewable Energy Laboratory, USLCI Database, National Renewable Energy Laboratory Golden, CO, 2021.

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