Operational Carbon Calculation Method

How to calculate operational carbon emissions using a custom carbon emission factor?

Patrick Chopson avatar
Written by Patrick Chopson
Updated over a week ago

The 2030 baseline carbon emission factors are calculated using the ZeroTool API EUI and cove.tool carbon emission factors.

What is an Emissions Factor?

An emission factor is a coefficient that allows converting activity data into GHG emissions. It is the average emission rate of a given source, relative to units of activity or process/processes. In cove.tool this is converting operational energy (EUI) to operational carbon emissions.

Calculation Method

The project Emissions factors are calculated directly using a constant value for Gas (181) and state/country-specific factors for Electricity. US electricity carbon factors are based on EPA eGrid database and Canada's National Inventory Report defines the carbon factors for Canadian provinces. Equivalent databases are used for international locations such as the Annual Climate Transparency Report.

Currently, cove.tool uses fixed carbon emission factors and it's not possible to edit the factors. However, if you want to manually calculate the operational carbon emission for your project with a different emission factor, here is the formula used for reference:

If co2_factor is not None: 
project_ghg_factor = (total_electric * co2_factor + total_gas * 181) * total_floor_area / 1000000 
baseline_ghg_factor = ((total_electric_perc * eui_2030 * co2_factor + total_gas_perc * eui_2030 * 181) * total_floor_area / 1000000)

Following the above formula, to use your own factors for carbon emission calculation, take the steps below:

  • Multiply each end use EUI by the projects total area to get the total energy used (in kBtu)

  • Sum end uses into their respective source energy. Cooling, Lighting, Equipment, Fans & Pumps are always electricity. Heating and Hot Water are per the primary energy settings on the baseline page.

  • Multiply results by the custom factors (note energy unit will be kBtu)

Note. The unit for CO2 factors is gCO2 e/ kwh

Last, find the operational carbon values for your project at the top of the baseline energy page in the app. See below.

Related Links:

Did this answer your question?