Fleet managers have long known how to track important fleet characteristics such as safety, fuel spend, and maintenance. However, objectively monitoring environmental performance has been unnecessarily challenging, until now.

Tracking fleet environmental performance can — and should — be straightforward. Many fleet managers already have all the data needed to track their fleet’s major environmental impact: greenhouse gas (GHG) emissions.

Monitoring and managing GHG emissions provide companies with high-quality data to help better understand their corporate environmental footprint, an issue becoming increasingly important to shareholders.


Why Greenhouse Gases Matter

The build-up of GHG in the atmosphere is raising global temperatures. These gases trap heat radiated from the earth’s surface, warming the lower atmosphere and surface temperatures. Unless we act today to reduce the buildup of these emissions, we will likely face extremely serious changes to the earth’s climate.

Transportation is a major source of greenhouse emissions, accounting for nearly one-third of U.S. emissions. According to the Environmental Protection Agency (EPA), passenger vehicles account for 62 percent of transportation emissions, and heavy- and medium-duty trucks account for another 20 percent.

Vehicles emit greenhouse gases mainly during the combustion of fuel. The most prominent greenhouse gas emitted is carbon dioxide (CO2). Methane (CH4) and nitrous oxide (N2O) are emitted in smaller quantities. Vehicles also contribute to global warming through non-combustion releases of air conditioning refrigerants (HCFCs). The good news is opportunities exist to significantly reduce these emissions.


Measuring GHG Critical

By designing their fleet "greening" efforts around the systematic measurement of GHG emissions, companies open the door to innovation, efficiency, and costs savings. This outcome-based approach empowers managers to use all tools available to them to deliver cost-effective environmental benefits.

Measuring emissions is at the heart of the program the Environmental Defense Fund developed with PHH Arval that has enabled its clients to reduce emissions, on average, by 14 percent while also reducing lifecycle operating costs.

Estimating Emissions

Calculating emissions from fuel consumption is highly accurate. Organizations without accurate fuel consumption records should explore steps to build a collection of fuel type and volume data into their accounting systems. In the meantime, managers can estimate their fleet CO2 emissions by using data on mileage and expected fuel economy.

A best practice when estimating emissions is to base estimations on fleet-specific data. For example, companies missing data from a small portion of their fleets similar in use and composition to the rest of the fleet can extrapolate from existing data.

For example, the manager of a fleet of 400 Chevrolet Impalas who has fuel consumption data for all but 50 of these vehicles could assume the remaining 50 vehicles achieve the average fuel economy of the other 350 vehicles. If mileage data is available for the 50 vehicles, their fuel consumption could be estimated by dividing the known mileage by assumed fuel economy. If mileage data also is not available, the manager can assume these vehicles emit the average amount of the 350 vehicles with good data.

A second-best method to estimate emissions is through mileage. The EPA publishes mpg ratings for passenger vehicles every year. Managers with good mileage data for their fleets can estimate fuel consumption by dividing vehicle mileage by expected fuel economy. For example,

18,000 miles / 20 mpg = 900 gallons of fuel consumed

This approach, however, does not adequately capture emissions influenced by operator behavior (i.e. idling, speeding, or underinflated tires). In addition, managers must make assumptions about their percentages of city and highway driving.


Managing Emissions

Once companies have a system in place to track emissions, the real work begins. Strategies that deliver immediate emission reductions, such as right-sizing vehicles, optimizing routing, reducing cargo weight, and minimizing idling, should be at the top of the fleet "to-do" list. Some companies might also want to explore alternative-fuel or advanced vehicle technology options. These strategies, too, can fit under a GHG management framework as long as the related emissions can be tracked.

Setting a fleet emission reduction goal is a good way to provide a focus and demonstrate a long-term commitment to these efforts. When setting the goal, companies should consider the potential emission benefits of strategies available to their fleets to improve fuel economy and reduce vehicle miles traveled. Based on this information, companies should set an aggressive, but achievable reduction goal and timeline.

"Greening" efforts will remain a focus for companies for years to come. Only by tracking fleet emissions will companies be able to document progress and make objective decisions about fleet greening strategies. Every organization is encouraged to measure fleet emissions and find emission-reduction opportunities today.


Step by Step: How to Measure Emissions

Step 1. Set a Baseline.

Among the first steps to creating a solid system for tracking emissions is deciding a baseline year and emission reduction goals. When first developing a GHG baseline, companies should calculate emissions for the past several years. Although eventually a single year is selected as the baseline, managers should look at multiple years to identify unusual trends and ensure the right starting point is selected.


Step 2. Aggregate total amount of fuel consumed by type.

Through fuel card records, driver receipts, or other sources, managers can calculate the amount of fuel consumed by the company fleet. Fuel should be tracked by type and volume, such as gallons of gasoline.


Step 3. Identify carbon dioxide coefficients.

When combusted, each fuel type releases a specific amount of carbon dioxide in the atmosphere. For example, gasoline emits 19.42 lbs. per gallon. (See Table 1 on page 6.) Information on these and other types of fuel is available through the EPA. For easy calculation, coefficients are presented by volume, not by energy content.


Step 4. Calculate carbon dioxide emissions.

To calculate the total amount of CO2 emitted by a fleet, multiply the total volume consumed of each type of fuel by the fuel-specific carbon dioxide coefficient. For example:

1,000 gallons of gasoline x 19.42 lbs. CO2 = 19,420 lbs. of CO2

This calculation covers the vast majority of a fleet’s overall emissions.


Step 5. Estimate remaining emissions.

Refrigerant leaks and CH4 and N2O emissions are also factors in a vehicle’s greenhouse gas emissions. Each of these gases is a significantly more potent greenhouse gas than CO2. However, they are typically emitted in much smaller quantities. Calculating these emissions is more complicated than CO2 emissions since they are dictated by other factors than the amount of fuel consumed.

Under normal operating circumstances, these gases make up a few percentages of a passenger vehicle fleet’s emissions. Managers can approximate these emissions by assuming they equate to 5.7 percent of CO2. Thus, total emissions can be calculated by using the following equation:

Total CO2 x 1.057 = Total Emissions

To continue the previous example, a fleet that emits 19,420 lbs. of CO2 is estimated to emit the equivalent of 1,107 lbs. of CO2 in the form of other GHG emissions. In the example fleet, total emissions are 20,527 lbs. CO2 equivalent (CO2e).

Companies that want to fully calculate CH2, N2O, and refrigerant emissions can follow the protocol developed by the EPA Climate Leaders program, www.epa.gov/stateply/basic/index.html.