Diesel Emission Quantifier (DEQ) 

Frequently Asked Questions (FAQs)
EPA-420-F-11-045

December 2011

Transportation and Climate Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

Diesel Emission Quantifier (DEQ) 

Frequently Asked Questions (FAQs)
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Table of Contents

Administrative ............................................................................................................................................................3

Logging In................................................................................................................................................................3

Saving Results.........................................................................................................................................................3

Changing Your Password ........................................................................................................................................3

Activating Your Account.........................................................................................................................................4

Uses and Limitations ..................................................................................................................................................4

Light Duty Vehicles.................................................................................................................................................4

Congestion Mitigation and Air Quality Improvement Program (CMAQ) ...............................................................4

State Implementation Plans (SIPs) .........................................................................................................................4

Fuel Savings/Fuel Economy Benefits......................................................................................................................5

CO2 ..........................................................................................................................................................................5

Truck Stop Electrification........................................................................................................................................5

C3 Marine ...............................................................................................................................................................6

Black Carbon...........................................................................................................................................................6

Defaults and Emission Rates ......................................................................................................................................6

Defaults ..................................................................................................................................................................6

Emission Rates........................................................................................................................................................6

Calculations and Units................................................................................................................................................7

Calculations ............................................................................................................................................................7

Units .......................................................................................................................................................................8

Use in the Grant Process............................................................................................................................................8

Choosing a Calculator.............................................................................................................................................8

Cost Effectiveness.......................................................................................................................................................8

Health Benefits........................................................................................................................................................ 12

Counties............................................................................................................................................................... 12

Pollutants and Health Effects.............................................................................................................................. 13

Calculation, Use, Purpose, and Accuracy ............................................................................................................ 14

Cost Benefits (Explanation and Troubleshooting)............................................................................................... 16

Other.................................................................................................................................................................... 17
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Data Entry................................................................................................................................................................ 17

Multiple Technologies......................................................................................................................................... 17

Fuel Type ............................................................................................................................................................. 17

Replacement........................................................................................................................................................ 18

Uncertainty, Missing Information, Averaging, and Diverse Fleets...................................................................... 18

Fleets ................................................................................................................................................................... 19

Baseline Emissions............................................................................................................................................... 19

Idling Hours.......................................................................................................................................................... 20

Maintenance and Operating Costs...................................................................................................................... 20

Vehicle Definitions and Classes........................................................................................................................... 20

Verification Information...................................................................................................................................... 20

Input Errors.............................................................................................................................................................. 21

Vehicle Groups .................................................................................................................................................... 21

Model Year .......................................................................................................................................................... 21

Horsepower......................................................................................................................................................... 22

Replacement (Engine and Vehicle)...................................................................................................................... 22

Technologies........................................................................................................................................................ 22

Fuels..................................................................................................................................................................... 22

Currently Documented Errors................................................................................................................................. 23

Appendix: Grouping Vehicles for Calculations in the DEQ...................................................................................... 25
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Administrative

Logging In

Question: What should I do if I’m having trouble logging in?

Answer: Try logging in again using your existing username and password. If you 

encounter further difficulties, try resetting your internet browser's history and 

cookies before attempting again. If you still cannot log in, create a new username 

and password.

Question: When I try to access the DEQ, I receive an error message. 

Answer: The DEQ tends to malfunction when many users are logged on at once. The 

tool resides on an EPA server that may be overwhelmed with heavy user traffic. 

We advise everyone to plan ahead as traffic will be high around the close of any 

National Clean Diesel grant competitions. Please try using the DEQ during offpeak hours (early morning or late evening, depending on your time zone, and 

possibly weekends). If you are unable to access the DEQ at any time, close down 

your browser and try again without logging in. Also, try using different browsers 

(the DEQ is configured to be used with IE, Mozilla, and other browsers). 

Saving Results

Question: Is there a way to save more than three Fleets using a single login account in 

the DEQ? 

Answer: No. However, with the exception of marine vessels, each Fleet allows you to 

add up to thirty Vehicle Groups. As of now, each marine vessel must have its own 

separate Fleet (with up to five marine engines per vessel/Fleet). You may open 

multiple accounts; just use a unique email address each time. 

Question: When trying to save quantifier results into excel format, it doesn't save 

properly. It saves as a txt file or comma format. What is the problem?

Answer: The DEQ allows users to save both the Summary Results and Detailed 

Results of a calculation in Excel and CSV formats. Sometimes, however, the files 

do not get saved properly due to browser and/or computer download settings. If 

you find that your results saved improperly as a text file, for example, just re-save 

or rename it with the “xls” extension and it should open just fine. If you need the 

results in CSV format, we recommend that you save the results in CSV directly 

from the DEQ, instead of saving the Excel version and then converting to CSV. 

Changing Your Password

Question: How do I change my DEQ password? 

Answer: To change your password, go to www.epa.gov/cleandiesel/quantifier/, select 

the tab that says "My Account," log in, and click “Edit Profile.”
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Question: I tried changing my DEQ password, editing the password in the “My 

Account” page as you suggest, and got the following reply when I had put in the 

new password and retyped it as requested: “Exception on Request. The action user 

update failed. Variable USER is undefined.” What should I do?

Answer: We are working to fix this problem. In the meantime, you should continue to 

use your old password.

Activating Your Account 

Question: I submitted registration information but I am unable to log in. Has my 

account not been activated? Will I receive a notification email when my account is 

activated?

Answer: Yes, you should receive an activation email with a validation link. Your 

account becomes activated after you click on that link. It is possible that the 

activation email for the Diesel Emissions Quantifier was caught in your SPAM 

filter, or you might have mistyped your email address in the registration form. If 

you are unable to find the email after looking in your SPAM filter, you can try reregistering the account and hopefully you will be able to receive the activation 

email. Sometimes, the DEQ server does not allow emails that end with “.net”, such 

as “Comcast.net” or “Verizon.net.” We are working to fix this and apologize for 

the inconvenience. We suggest that you register with an email that ends with “.gov, 

.edu, or .com.” 

Uses and Limitations

Light Duty Vehicles

Question: Can the DEQ be used for light duty projects (i.e. diesel pickups)?

Answer: The DEQ calculates emission reductions for medium-heavy and heavyheavy-duty vehicles only. The Motor Vehicle Emissions Simulator (MOVES) 

model (www.epa.gov/otaq/models/moves/index.htm) can be used to calculate 

emission reductions for both heavy-duty and light-duty vehicles. 

Congestion Mitigation and Air Quality Improvement Program (CMAQ)

Question: Can the DEQ be used to estimate benefits for the Congestion 

Mitigation and Air Quality Improvement Program (CMAQ)?

Answer: Yes, the DEQ is an estimation tool that may be used for CMAQ planning 

purposes.

State Implementation Plans (SIPs)

Question: Why can’t the DEQ be used for State Implementation Plan (SIP) 

calculations?
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Answer: The DEQ is intended to help in preparing estimated results from retrofit 

projects. Certain data which can affect emissions, such as temperature and 

humidity, are entered as default values in the DEQ. Specific inputs are required for 

the more sophisticated modeling tools approved for SIP and conformity 

calculations. Please refer to your SIP and conformity guidance document and 

consult with your EPA Regional Office. 

Fuel Savings/Fuel Economy Benefits

Question: Does the DEQ provide actual fuel savings or estimates?

Answer: The DEQ does not provide information on fuel savings. Based on the user’s 

input of the amount of fuel used, the DEQ will calculate CO2 emissions reductions 

for select technology types. 

Question: Does the DEQ calculate fuel and emissions savings as a result of vehicle 

replacement or repower?

Answer: No, not at this time. However, there is a field that allows a user to input 

potential fuel savings from replacements/repowers, and the input will then be used 

to calculate CO2 emission reductions. 

CO2

Question: Would an engine replacement produce CO2 (carbon dioxide) emission 

reductions? 

Answer: There is a potential for CO2 reduction with an engine replacement in addition 

to the amount reduced from burning less fuel, however engines are not currently 

certified with CO2 values. In addition, most testing programs do not include CO2 as 

a measured pollutant. Hence, CO2 data is severely limited at this time and we are

working to make this clearer on the main DEQ page. 

Truck Stop Electrification 

Question: How are emissions quantification and cost-benefit analysis applied to the 

use of TSE? 

Answer: The DEQ is able to quantify TSE benefits for trucks as an Idle Reduction 

Technology. As you run the calculation, please make the best estimate you can on 

the number and type of trucks that would utilize the TSE facility, as well as the 

amount of idling hours reduced. 

The DEQ can perform cost effectiveness calculations in two ways. First, it can give 

you a dollar per ton of pollutant reduced based on your input for the cost of the 

whole TSE project. You would input this cost before you add the Vehicle Group. 

Second, the DEQ can give you the dollar per ton of pollutant reduced for the cost 

each technology and installation (in this case, TSE spaces). You enter these costs 
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as you are adding a technology to your vehicle group. The first cost effectiveness 

value appears only on the “Results” screen, while the second appears both on the 

“Results” screen and the Summary and Detailed results spreadsheets. 

C3 Marine 

Question: Do you envision including C3 marine vessels in the DEQ?

Answer: C3 marine engines, or ocean-going vessels, are currently beyond the scope 

of what is modeled in the DEQ. EPA has provided “Current Methodologies in 

Preparing Mobile Source Port-Related Emission Inventories” to help users 

calculate emissions reductions. Please contact EPA’s Helpline at 1-877-NCDCFACTS or cleandiesel@epa.gov for assistance with the calculations.

Black Carbon

Question: Black carbon, also known as elemental carbon, is a potent climate 

change agent found in diesel particulate matter. Does EPA have plans to include 

black carbon in the DEQ so the climate change impacts can be estimated? 

Answer: The EPA as a whole is still working on reports and guidance regarding black 

carbon. At this time, there are no definite plans to include black carbon in the 

DEQ.

Defaults and Emission Rates

Defaults

Question: Can you explain the DEQ default values?

Answer: The DEQ default values were compiled using various reports and models. 

Please see the DEQ Default Values document 

(www.epa.gov/cleandiesel/documents/420b10035.pdf). 

Question: How does the DEQ calculate the life of a vehicle? Can that value be 

overridden? 

Answer: The DEQ considers the application, engine type, and model year in 

generating a default lifetime for each vehicle. For on-highway vehicles, the 

lifetime is set at 30 years; for non-road applications, the lifetime is usually shorter 

but will vary depending on equipment type and horsepower. Please see Appendix 

C of the DEQ User’s Guide for detailed breakdowns of vehicle lifetimes. These 

default lifetimes cannot be overridden. 

Emission Rates

In November 2010, emission rates in the DEQ for highway/on-road vehicles were 

updated using data from the Mobile Vehicle Emissions Simulator (MOVES2010). 

MOVES2010 incorporates many significant improvements over the old MOBILE6.2 
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in baseline emissions, activity data, and calculations used to estimate emissions in 

real-world driving conditions. For current and future highway/on-road projects, it is 

highly recommended that you use the MOVES2010 emission rates by selecting retrofit 

year of 2011 or later. 

Question: Which "Year of Retrofit Action" should I use if my project spans several 

years, for instance 2008 to 2011? 

Answer: We recommend that you use MOVES numbers by selecting 2011 as the 

"Year of Retrofit Action" for the entire project, even if the retrofit activity took 

place before 2011.

Question: Which model should I use if my project spans 2008 -2011 and my initial 

calculations used the old DEQ (MOBILE 6.2) emission rates? 

Answer: We still recommend that you perform your final calculations using MOVES 

by choosing 2011 as your "Year of Retrofit Action". 

Question: My project has been completed and I’ve already done my calculations 

using the old DEQ numbers? Do I need to re-run the DEQ using 2011 as the "Year 

of Retrofit Action"? 

Answer: No. If your project is closed and you have already turned in your final 

report, there is no need to re-run the DEQ. 

Question: If I want to continue using the old DEQ MOBILE 6.2 emission rates, will 

I run into problems? 

Answer: You will not run into any problems using the DEQ. However, using the old 

MOBILE 6.2 numbers for your calculations will severely under estimate your 

emission reductions. 

Calculations and Units

Calculations

Question: In calculating lifetime benefits, does the DEQ consider the remaining life 

of the vehicle or of the emission control device? 

Answer: Lifetime calculations are based on the remaining life of the vehicle, not the 

emission control device. EPA assumes that once a vehicle is retrofitted, it will 

remain retrofitted until the vehicle is retired. 

Question: Why is the lifetime calculation presented in terms of a vehicle’s remaining

life instead of its whole lifetime? For instance, I am replacing a twenty-year-old 

school bus with a brand new one. The old bus has ten years left while the new one 
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has thirty. The DEQ will show lifetime emission benefits for only those ten 

remaining years. Isn’t this underestimating the emissions benefit for my new bus? 

Answer: The DEQ is showing emissions benefit for only the remaining life because 

after the tenth year, the old bus would have been replaced anyway. Therefore, you 

are getting credit for only those ten years of early attrition. 

Units 

Question: Does the DEQ give results in metric tons or short tons? 

Answer: Short tons.

Question: Can the DEQ separate Particulate Matter (PM) by PM2.5 and PM10? 

Answer: No. The DEQ only calculates PM2.5. 

Use in the Grant Process

Choosing a Calculator

Question: If the DEQ cannot accommodate my project, what are some other 

calculation tools I can use?

Answer: You may utilize the following alternative methods for calculating 

emission reductions: 

1. Motor Vehicle Emission Simulator (MOVES) (on-road vehicles) 

www.epa.gov/otaq/models/moves/index.htm

2. Nonroad Model (nonroad engines, equipment, and vehicles) - 

www.epa.gov/otaq/nonrdmdl.htm 

3. SmartWay FLEET Model - www.epa.gov/smartway/partnership/ 

Cost Effectiveness

Question: How is cost effectiveness determined? 

Answer: The DEQ calculates two types of cost effectiveness, but both calculations 

are simple and can be done by hand. 

First, the DEQ calculates Total Cost Effectiveness by summing up the financial 

inputs you make on this first screen of the DEQ calculation. This is the Total 

Project Cost. 
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Next, you will make all the inputs for your vehicles and click “Quantify 

Emissions.” The DEQ will sum up the lifetime tons reduced across all the vehicles 

based on pollutant (NOx, PM, HC, CO, and CO2). This is the Total Lifetime Tons 

Reduced. Finally, the DEQ divides the Total Project Cost by the Total Lifetime 

Tons Reduced for each of the five pollutants, performing individual divisions for 

each pollutant. This gives five results in dollars/ton and is shown on the bottom of

the Emission Results Page ONLY. It is currently NOT shown on the Excel or 

CSV DEQ outputs for download. However, this is a relatively simple calculation 

that can be done by hand after a DEQ run is completed. 
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Second, the DEQ calculates Capital Cost Effectiveness by taking the sum of the Unit 

Cost and Installation Cost of each technology (shown below), and dividing that by the 

Total Lifetime Tons Reduced for each of the five pollutants. This value is displayed 

both on the Emissions Results page and the Excel and CSV DEQ outputs for download.
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Health Benefits

Counties

Question: How do I choose the counties in which the emission reductions take place? 

Answer: For a DEQ calculation, you are required to choose one state where the 

retrofits take place. For projects that span multiple states, such as long-haul 

trucks and locomotives, please choose the state where the majority of the 

emissions are located. 

Once you complete the DEQ run and get to the DEQ Health Benefits Module, you 

will be allowed to allocate emission reductions among up to five counties (across 

multiple states) for the purpose of estimating monetary benefits. Please use your

best judgment, based on your understanding of where the emission reductions will 

take place, to determine which counties should be included in the benefit estimates. 

Note that the Health Benefits Module is not asking whether pollution from one 

county is drifting into another; it’s asking where the vehicles that are reducing their 

emissions are operating.

Question: My county is “flagged.” What does that mean? 

Answer: The Health Benefits Module will flag results for counties where there may 

be an underestimate or an overestimate of benefits due to the transport of emissions 

into or out of the county. 

For counties where a large quantity of emissions are flowing into the county, the 

results are flagged with the following message: Benefits estimates are “flagged” 

for this county, indicating that we have less confidence in these results due to a 

large amount of inter-county transport of emissions. The impacts estimation tool 

may be overestimating the benefits for emissions reduction projects in this county, 

because it has relatively few emissions compared to surrounding areas. As a 

result, this county is likely to be a net importer of diesel emissions, and air quality 

is significantly affected by emissions in upwind counties. Please take this increased 

uncertainty into account when interpreting your results. 

For counties where a large quantity of emissions are flowing out of the county, the 

results are flagged with the following message: Benefits estimates are “flagged” 

for this county, indicating that we have less confidence in these results due to a 

large amount of inter-county transport of emissions. The impacts estimation tool 

may be underestimating benefits for emissions reduction projects in this county, 

because it has a relatively high density of emissions compared to surrounding 

areas. As a result, this county is likely to be a net exporter of diesel emissions, and 

many of the benefits of reducing these emissions are likely to take place in 
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downwind counties. Please take this increased uncertainty into account when 

interpreting your results.

Question: When I enter the same data for vehicles and retrofit projects in different 

counties, I get different benefits. Why? 

Answer: One of the main factors determining magnitude of health benefits 

associated with a given emissions reduction is the proximity of the emissions to 

people. If a certain emissions level is assigned to a larger census tract, it will 

result in a lower ambient concentration as the pollution is being spread over a 

larger area. The opposite is true as well. Assigning emissions to a smaller census 

tract will result in higher average concentrations. 

In addition, if emissions are assigned to a less populated census tract, fewer people 

will be exposed to the resulting concentration of air pollution and the populationweighting at the county scale will predict a lower concentration, and thus, a lower 

ratio. Again, the opposite is true: emissions assigned to higher-populated tracts 

leads to a higher concentration and ratio.

Pollutants and Health Effects

Question: What health effects of diesel PM are included in the monetary calculation 

of the Health Benefits Module?

Answer: The monetary values for the benefits of reducing diesel emissions 

are based on avoided incidences of the following health effects: 

• Premature mortality 

• Chronic bronchitis 

• Acute bronchitis 

• Upper and lower respiratory symptoms 

• Asthma exacerbation 

• Nonfatal heart attacks 

• Hospital admissions 

• Emergency room visits 

• Lost work days 

• Minor restricted-activity days 

Question: Does the DEQ estimate reductions in total particulate matter or fine 

particulate matter, since the Health Benefits Module aspect of the DEQ uses only 

PM2.5 in its calculation? 

Answer: The DEQ estimates reductions in PM2.5, as does the Health Benefits Module. 

For additional information about this conversion, please refer to the Health 

Benefits Methodology (www.epa.gov/cleandiesel/documents/420b10034.pdf). 
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Question: Is diesel particulate matter the only pollutant considered in the Health 

Benefits Module? 

Answer: This module estimates the benefits from reducing only the portion of diesel 

particulate matter that is fine particulate matter (PM2.5). There are likely benefits 

from reducing other pollutants, such as ozone and air toxics, but the DEQ is not 

able to quantify these benefits at this time.

Calculation, Use, Purpose, and Accuracy

Question: How are benefits of reducing diesel particulate matter calculated? 

Answer: The Health Benefits Module uses a county-scale “look-up table” within the 

larger DEQ tool. The look-up table includes estimates of monetary benefits per ton 

reduced of PM2.5 reduced for each county in the United States. The user answers a 

set of questions about the type of engine being controlled, the emission control(s) 

used, and the location of the emission reductions. Once the DEQ estimates the 

emission changes, users can choose to have the Health Benefits Module estimate 

the health benefits of reductions in fine particulate (PM 2.5) emissions. Those 

results are found in the look-up table and the combined monetary values of avoided 

mortality and morbidity (i.e. non-fatal illness) are presented in tabular format for 

the counties the user identified. 

EPA has developed look-up tables for total diesel PM sources, as well as for onroad diesel sources and non-road diesel sources. The look-up table for total diesel 

PM sources was developed as part of the Quality Assurance for this module and 

are the sum of the on-road and non-road look-up tables. These tables and more are 

available in the Health Benefits Methodology located on the DEQ website. 

Question: How can this information be used for?

Answer: The Health Benefits Module is intended as a helpful tool in preparing and 

understanding estimates for specific emission diesel reduction projects. It can be 

used to make informed decisions about the benefits of various diesel retrofit 

options, provide an estimate of benefits for EPA grant applications, and build 

public support for such projects. However, it should not be used in the calculation 

of emission reductions for State Implementation Plan (SIP) or conformity 

determination.

Question: What does the Health Benefits Module provide? 

Answer: This module provides information on the health benefits of reducing 

exposure to diesel PM emissions. This new component of the DEQ allows users to 

estimate diesel emission reductions and the resulting health benefits. 
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The DEQ requires users to input detailed information regarding the emission 

sources they are controlling, the types of controls being applied, the number of 

sources being replaced, retrofitted or otherwise controlled, and the year in which 

the controls will take effect. The DEQ then calculates the emission reductions for 

particulate matter (PM), nitrogen oxides (NOx), hydrocarbons (HC), carbon 

monoxide (CO), and carbon dioxide (CO2). 

The Health Benefits Module allows users to identify the counties where the 

emission reductions are taking place and to estimate the monetary impact of the 

resulting health benefits. These estimates are based solely on the change in fine 

particle concentrations and do not reflect changes in exposure to any other 

pollutants, including ozone or hazardous air pollutants. Users can save and export 

files summarizing the emissions and health effects estimates. There is also a Health 

Benefits Methodology that explains the methodology used to estimate the health 

benefits and the limitations of the estimates.

Question: How accurate are the Health Benefits Module estimates? 

Answer: The benefits generated by this module reflect reductions only in fine 

particulate matter. They do not include benefits from the reduction of other 

pollutants, including air toxics. 

The results also do not include the impact of emissions sources from neighboring 

countries (i.e., Canada or Mexico), so the results for states bordering either of these 

countries do not reflect these potentially significant sources of transported 

emissions. 

The methodology used to estimate the health benefits for this project was peer 

reviewed both inside and outside EPA and incorporates many suggestions by the 

peer reviewers. It includes data and modeling from several existing EPA tools: 

the National Emissions Inventory (NEI), the National Air Toxics Assessment 

(NATA), and the Environmental Benefits Mapping and Analysis Program 

(BenMap). 

The methodology is most accurate in a relative sense, such as when comparing 

benefits among different locations or retrofit projects. The estimates are based 

primarily on county-level data and do not capture smaller-scale variability in air 

quality, exposure, or benefits, such as living very near a retrofitted diesel source 

or regularly riding a retrofitted school bus. 

For a complete discussion of the accuracy of these estimates, please see the chapter 

in the methodology document titled “Uncertainties, Limitations, and Quality 

Assurance.”
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Cost Benefits (Explanation and Troubleshooting)

Question: Why does the Health Benefits Module use annual costs and benefits? 

Answer: Diesel retrofit projects tend to be capital-intensive in the first year with the 

purchase and installation of new equipment or parts. The benefits, however, are 

spread out over many years as people receive health benefits from the reduced 

emissions from the new or retrofitted engine. In order to adequately compare costs 

and benefits, this difference in timeframes must be accounted for. We annualize 

the costs and the benefits so the user can tell at a glance whether the benefits 

outweigh the costs on an annual basis. These annualized costs and annual benefits 

provide an indication of the scale and magnitude of the expected costs and benefits 

over the lifetime of the project.

Annualized costs are not the out-of-pocket costs in the first year, but are what 

would be paid each year if the out-of-pocket costs were distributed the over the life 

of the engine. This is similar to the way a mortgage distributes costs over 30 years. 

If you took out a loan to purchase the retrofit technologies, the annualized costs are 

roughly what the loan payments might look like. 

Lifetime costs and benefits can be estimated by multiplying the annual costs or 

benefits by the number of remaining years in the lifetime of the retrofitted engine. 

While the lifetime estimate does not take into account a number of factors such as 

discount rates for benefits in future years, population or income growth, and others, 

it does provide a rough estimate.

Question: Why are there no costs in the “Results” table of the Health Benefits 

Module? 

Answer: The Health Benefits Module estimates the annualized costs from the unit 

cost (equipment) and installation costs of the project. These values are entered at 

the bottom of the DEQ input section titled “Apply a Technology.” If the user 

does not enter the cost information, no cost information will appear in the 

benefits results table. 

In addition, funding information may be entered in the section titled “Click Here to 

Enter Funding Information.” These are assumed to be total project costs, including 

overhead, and are not used to estimate annual costs.

Question: I am trying to determine the health benefits for a marine engine repower 

project. While there are significant PM reductions in PM nonattainment counties, 

the benefits come up $0. What is the problem?
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Answer: The health benefits calculation depends on the PM reduction in tons. 

Sometimes, that reduction may be lower than you realize and the benefits for the 

chosen counties may be very close to zero that they’re accidentally truncated. 

Please download the Summary Results of both the DEQ calculation and the 

Health Benefits calculation in Excel or CSV and send it to Cleandiesel@epa.gov 

Other

Question: Where can I get more information about the health benefits of reducing 

particulate matter in diesel emissions? 

Answer: For information about particulate matter, visit 

www.epa.gov/air/particlepollution 

Data Entry

Multiple Technologies

Question: Is there a scenario for using the DOC+CCV (Diesel Oxidation Catalyst + 

Closed Crankcase Ventilation) or DPF+CCV (Diesel Particulate Filter + Closed 

Crankcase Ventilation) combination technology? How about CCV by itself? 

Answer: CCV is included under “Emission Control Devices” as DOC+CCV, or 

DPF+CCV. It is not listed as a stand-alone retrofit technology. If you are using 

CCV as a stand-alone technology, select “Other Emission Control Devices” from 

the “Technology” menu and enter the reduction percentages as given by the CCV 

manufacturer. 

Question: Is there an option for combined technologies such as engine repower with 

DOC or DPF? 

Answer: Some combined technologies are not available together because they cannot 

or should not be installed on the same vehicle (i.e. DPFs and Partial Flow filters). 

However, there are many technologies that can be installed together and you can 

add them to the same vehicle(s). This is done by first selecting one technology and 

adding it to your vehicle group and then selecting another and saving it to the same 

vehicle group. Work slowly and pay close attention to how the multiple 

technologies are displayed on the screen. If you have multiple vehicle groups, be 

aware that after adding a technology, the page always reloads to show the first 

vehicle group, so remember to scroll down if you’re working on a subsequent one. 

Fuel Type

Question: With our retrofit project, we will be switching from one fuel type to 

another. How is this handled in the DEQ? 
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Answer: First, go to the “Enter New Vehicle Group Information” section and enter 

the vehicle information. Then select the fuel type that was being used before the 

retrofit.

Under “Apply a New Technology to the Vehicle Group,” apply as many 

technologies as you need to the vehicle(s). One of the “Technology Type” options 

is “Fuel Options,” so select the fuel that the vehicle(s) will be using after the 

retrofit.

Replacement

Question: Does the DEQ also calculate emissions reductions for engine 

replacements? 

Answer: Yes. Under “Technology Type,” select “Engine Replacement/Repower.”

Then under “Technology” select “Engine Replacement.”

Question: Can the DEQ be used to calculate emission reductions by replacing a 

diesel engine with electric technology? 

Answer: Replacing a diesel engine with an electric technology would result in zero 

diesel emissions. In this case, you would enter all the fleet information and when 

you add a Retrofit Technology, select “Emission Control Devices,” for Technology 

Type, and then select “Other Emissions Control Devices” for Technology. Then, in 

the “Reduction by Pollutant”, you can enter 100% for each of the pollutants. This 

allows the DEQ to calculate your project with all of the diesel emissions removed. 

Uncertainty, Missing Information, Averaging, and Diverse Fleets

Question: We have a project that has a variety of fleet components, but we are unsure 

of the exact vehicles that will be in the program. What should we use for the DEQ 

calculations?

Answer: If you are unsure of the exact fleet, you should use your best judgment and 

any past history you have with such a program to make estimates in the DEQ. 

Question: What if I don’t have all of the information required to use the DEQ? 

Answer: The DEQ offers some default values for various equipment and retrofit 

technologies in the DEQ Default Values document 

(www.epa.gov/cleandiesel/documents/420b10035.pdf). Some of these defaults 

can be self-populated as you run the DEQ (but not all, so remember to check the 

defaults document). When you add a Vehicle group, there will be a link called 

“Get Default Values,” which will populate certain fields if you click on it. You can 

also make estimates using different scenarios if certain data (e.g., gallons of fuel 

used annually) are not readily available. However, we do encourage everyone to 
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use real-life data and challenge fleet owners and operators to have records of data 

for their vehicles. 

Question: For off-road vehicles, DOC unit cost varies depending on engine size. Can 

we average the costs per unit or must we do a separate run for each application? 

Answer: You can either use one unit or average them, depending on how you will use 

your data and how precise you want your results to be.

Question: How do you estimate emissions for a fleet with multiple, diverse 

vehicles? Must a separate calculation be performed for each vehicle? 

Answer: It depends on your preference and the desired precision of the results. You 

may generate a report for each vehicle or group of similar vehicles. Alternately, 

you may run a single report using ‘average’ inputs to minimize the number of runs. 

For example, if similar vehicles are spread evenly over model years 1998 -2003, 

they may be averaged together, entered as 2001, and run as a single report. For 

more information on the best ways to group vehicles and still ensure accuracy, 

refer to the Appendix of this document. 

Fleets

Question: How many vehicles make a fleet? 

Answer: One or more vehicles, engines, and/or equipment (i.e. stationary generator). 

Question: Which inputs are for a single vehicle and which are for the entire fleet? 

Answer: All of the inputs except for Fuel Volume should be entered for a single 

vehicle/engine. Fuel Volume should be entered as a total for the entire Vehicle 

Group. 

Baseline Emissions

Question: How can I calculate baseline emissions using the DEQ?

Answer: To calculate baseline emissions, simply enter the information about your 

fleet, and then when you add a technology, choose “Emission Control Devices” for 

Technology Type and “Other Emission Control Devices” for Technology. This 

will give you zero percent reductions and the results will simply be the baseline 

engine emissions. However, if you do not add any technology to your fleet, the 

DEQ will calculate the baseline emissions and you can view it on the Emission 

Results Screen, but the results cannot be downloaded as a DEQ Summary Results 

spreadsheet. 
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Idling Hours

Question: Are idling hours included in the non-road usage rate or are they just 

ignored? 

Answer: Please include idling hours as part of the engine's usage rate. 

Maintenance and Operating Costs

Question: Why are maintenance and operating costs not entered into the DEQ? 

Answer: These costs associated with a retrofit project do not have specific input fields 

in the DEQ, however, you may choose to include them as part of the total project 

cost, which is entered as you first begin to create a fleet. 

Vehicle Definitions and Classes

Question: Where can I find the definition of a bus and does it include hotel/airport 

shuttles?

Answer: For highway vehicles, only medium heavy-duty and heavy heavy-duty 

vehicles can be calculated in the DEQ (Classes 5-8). Shuttles are usually Class 4 

or 5, so be sure to double check your fleet. Only school buses and transit buses 

have separate categories. For a further definition of vehicles and weight classes, 

please see the DEQ Default Values document 

(epa.gov/cleandiesel/documents/420b10035.pdf). 

Question: Where can I find the definition of different classes of vehicles? Are they 

DOT classes? Are there any specifications for classes specifically related to 

DERA?

Answer: For highway vehicles, only medium heavy-duty and heavy heavy- duty 

vehicles can be calculated. See below for class breakdowns their respective gross 

vehicle weight rating (GVWR). 

• Class 5; 16,001 - 19,500 lbs GVWR

• Class 6; 19,501 - 26,000 lbs GVWR

• Class 7; 26,001 - 33,000 lbs GVWR

• Class 8a; 33,001 - 60,000 lbs GVWR

• Class 8b; 60,001 lbs GVWR and over

For further definitions of vehicles and weight classes, please see the DEQ Default 

Values document (epa.gov/cleandiesel/documents/420b10035.pdf). 

Verification Information

Question: Does EPA have a listing of engine family names that are approved for a 

verified product or system? 
Page 21 of 27

Answer: No, unlike CARB, EPA does not issue a list of engine family names 

for each technology verification. However, applicants should refer to the 

technology listing on the verified list for specific engine model/application 

information, as well as general operating criteria. Engine certification data, 

including engine family names, are available at 

www.epa.gov/otaq/certdata.htm#largeng

Input Errors

Vehicle Groups

Question: What if I have vehicles in both on-road and off-road applications? 

Answer: The DEQ can support multiple Vehicle Groups, including a mix of onhighway and non-road in the same Vehicle Group and Fleet. However, for marine 

engines, each marine vessel must be its own separate Fleet (with up to five engines 

per Fleet/vessel). 

Question: The quantifier is not allowing me to update Fleet information. The error 

happens when I try to add a vehicle group. I get this message: “An Unexpected 

Error has Occurred. We are sorry, the Diesel Emissions Quantifier has 

experienced an unexpected error. The details of this error have been logged and 

the development team has been notified. If you left your browser inactive for over 

30 minutes, this error is due to your session timing out.” What should I do?

Answer: If you are logged into a user account, one potential remedy would be to 

logout, close down the browser and then log back in again. You can also try 

running the quantifier without signing. 

Question: Is there a limit to how many vehicle groups we can input into one Fleet? I 

have 47 entered and when I try to quantify emissions it says the DEQ is 

experiencing an error.

Answer: Ideally, each Fleet can support up to 100 Vehicle Groups. However, most 

users see an increased number of crashes and malfunctions when there are more 

than 30 Vehicle Groups per Fleet. We recommend that you keep it to 30 or fewer. 

Model Year

Question: Sometimes when I am trying to enter my Vehicle Group information, I 

cannot select the model year I want for my vehicles. 

Answer: Depending on the type of vehicle, the DEQ may assume that only certain 

model years are allowed to be retrofitted. In this case, you should select the closest 

model year to your fleet, which will have an effect on the estimated results.
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Horsepower

Question: The DEQ does not have the horsepower that I need for a calculation. The 

nearest available horsepower option is either too high or too low. What should I 

do?

Answer: We still recommend using the nearest available horsepower option for the 

vehicles involved. Please understand that at this time, the DEQ does not have all 

emission factors for all available horsepower of non-road equipment. Data 

collection and approval on emission factors may take years, so please understand 

that the DEQ cannot readily perform all calculations at this time. 

Replacement (Engine and Vehicle)

Question: I can’t find an option to run a vehicle replacement. What should I do? 

Answer: The quantifier does not have an option for vehicle replacements. To 

calculate emissions reductions for a vehicle replacement project, please use the 

engine replacement option from the quantifier's technology list.

Technologies

Question: If idle reduction cannot be selected for off-road equipment, how do you 

quantify emission reductions for automatic shutdown devices on off-road vehicles? 

Answer: At this time the DEQ does not support idling strategies in non-road engines. 

You are welcome to consult other calculation methods. 

Question: When using the Diesel Emissions Quantifier, only verified technologies are 

available on the technology pull-down menu. Are Emerging Technology applicants 

supposed to manually insert projected emissions reductions in the HC, PM, CO, 

etc. areas? 

Answer: Yes. Please refer to the Emerging Technology RPF or RFA for specific 

instructions. 

Question: I’m having trouble calculating percent emission reductions for several 

technologies (including direct fired heaters which results in 0%). What might be 

the problem?

Answer: Go back and check your inputs for errors. For example, if the “Idle Hours 

Reduced” is blank, then you need enter the number of idle hours reduced per 

vehicle per year. 

Fuels

Question: What if the DEQ doesn’t list the same fuel blends that we have, like high 

blends of Biodiesel plus ULSD? 
Page 23 of 27

Answer: The DEQ results are estimates, so users are advised to select the option that 

most closely approximates their real-world application.

Question: The DEQ has selections for B-20 and B-100 but nothing in between. The 

National Clean Diesel RPF indicates that any blend of Biodiesel (B-5 to B100) is 

eligible. Are any blends eligible or just B20 and B100? 

Answer: Yes, any blend of Biodiesel is eligible. However, the DEQ at this time is not 

able to accommodate blends other than B20 and B100. Realize that the DEQ is 

simply a tool for estimates and you are welcome to seek out other tools that may be 

more geared toward fuels. 

Question: Suppose a company has a total of 20 trucks and has decided to replace the 

engines in 10 of them. For the combined fuel volume for the fleet, do we enter the 

total fuel consumed by the 20 trucks or by just the 10 of them which are going to 

be replaced? 

Answer: In the case you described, you would create a Vehicle Group of 20 vehicles 

in the DEQ and then apply the emission technology (in this case, an engine 

replacement) to 10 out of the 20 vehicles. For Fuel Volume, you would enter the 

combined fuel consumption for the entire Vehicle Group (all 20 trucks).

Currently Documented Errors

Please note that the DEQ is an estimation tool only and users may not be able to 

quantify all possible scenarios. EPA suggests you familiarize yourself with the data 

that goes into the DEQ (as outlined in the Appendices of the DEQ User’s Guide, the 

Health Benefits Manual, and the current methodologies for ports at 

www.epa.gov/cleandiesel/publications.htm#ports). If the DEQ is not working for 

your scenario, you may want to download the emissions factors from 

www.epa.gov/otaq/nmim.htm to make your own calculations. You can also use other 

available data sources. 

If you are using the DEQ for a DERA application, you can use any documented 

methodology to calculate emission reductions as long as you cite the source in the 

application. 

The instructions to use the DEQ can be found in the DEQ User’s Guide 

(www.epa.gov/cleandiesel/documents/420b10033.pdf) 

We have documented some common errors and suggested work-around solutions 

below. If the problem you are encountering is not listed, we recommend logging out, 

restarting the DEQ, and trying again. If the error persists more than twice, please send 
Page 24 of 27

us your inputs and take a screen shot or copy and paste the error message into an 

email. 

Problem: I can’t log in to my user account.

Solution: Please create a new user account.

Problem: My previously saved Fleets are not working. 

Solution: Due to updates to the DEQ structure, some previous scenarios may no 

longer work properly. If you encounter this situation, please delete the old Fleets

and recreate them. In some cases, users are able to access a saved Vehicle Group, 

but not be able to quantify it. This can be fixed by deleting the existing technology, 

re-entering it, and then clicking on “Quantify Emissions.” 

Problem: I can’t find Total Cost Effectiveness on the exported results spreadsheets.

Solution: This value is available on the Summary Results screen, but not available on 

the spreadsheets yet. Please refer to the page directly after clicking "Quantify 

Emissions,” or calculate yourself:

• The DEQ calculates Total Cost Effectiveness by taking the total funding for a 

scenario and dividing it by the total Lifetime Tons Reduced of each pollutant. 

• The DEQ calculates Capital Cost Effectiveness by taking the total Unit Cost and 

Installation Cost for each run and dividing that by the Lifetime Tons Reduced for 

each pollutant.

Problem: I am unable to select the correct Retrofit Year when I enter my older 

vehicles.

Solution: Choose a Model Year that is within 28 years of the Retrofit Year. For 

example, if you use a model year of 1990 instead of 1981, the DEQ will allow you 

to choose a retrofit year of 2009. 

Problem: The Lifetime Emissions equal the Annual Emissions.

Solution: The agency standard regarding diesel vehicles is that they should be retired 

after 28 years. Although many vehicles are used for significantly longer periods of 

time, the DEQ assumes that if a vehicle is over 28 years of age, its remaining 

lifetime is just one year, so the Lifetime Emissions equal the Annual Emissions. 

One way to work around this issue is to estimate the remaining life of the vehicle 

yourself and multiply the Annual Emissions accordingly.
Page 25 of 27

Appendix: Grouping Vehicles for Calculations in the DEQ

The Diesel Emissions Quantifier is designed to give emissions reductions for a variety of fleets and 

retrofit technology options. However, you may encounter a project with a multitude of vehicle and 

engine types. For instance, if your project is replacing 20 school buses with unique model years ranging 

from 1980 to 2000, you do not have to run the DEQ twenty different times for each individual model 

year. You can easily divide those 20 buses into two or three groups and run the DEQ two or three times. 

The following guidelines are based on the On Highway and Non-road emission standards (see Reference

Links): 

1) First, separate the DEQ Calculation Groups for multi-sector projects into three categories, On 

Highway, Non Road, and Marine. 

a) On Highway. 

i) First, group all on-highway vehicles into their respective Target Fleets: 

(1) City/County Vehicle 

(2) Delivery Truck

(3) School Bus 

(4) Transit Bus 

(5) Refuse Hauler

(6) Emergency Vehicle

(7) Long Haul 

(8) Short Haul 

ii) Within each Target Fleet, group vehicles based on the Class/Equipment: 

(1) School Buses 

(2) Transit Busses

(3) Class 5

(4) Class 6

(5) Class 7

(6) Class 8a

(7) Class 8b

iii) Next, divide the Class/Equipment groups by the following Model Year ranges (based on the 

On-Highway PM level emission standards ) : 

(1) Pre-1987 

(2) 1988-1990 

(3) 1991-1993 

(4) 1994-1997 

(5) 1998-2003 

(6) 2004-2006 

(7) 2007-2010 
Page 26 of 27

iv) Finally, within each Model Year group, divide your vehicles based on the type of retrofit 

technology that will be applied (i.e. Diesel Oxidation Catalyst + CCV, Engine Replacement, 

etc)

b) Non-Road (non-marine vessels/engines) 

i) First, group all Non Road vehicles into their respective Target Fleets: 

(1) Agriculture 

(2) Construction 

(3) Ports and Airports 

(4) Rail

(5) Stationary

ii) Within each Target Fleet, divide the vehicles based on the Class/Equipment (too many to list 

here, and realize that some non-road equipments can overlap so you could have fewer groups 

than you realize). 

iii) Within each Class/Equipment group, divide by the following Horsepower/Model Year 

combinations (based on Non-road emission standards for NOx, PM, NMHC+NOx and CO): 

(a) <11 hp and pre-2000 (Tier 0) 

(b) <11 hp and 2000-2004 (Tier 1) 

(c) <11 hp and 2005-2010 (Tier 2)

(d) 11≤ hp <25 and pre-2000 

(e) 11≤ hp <25 and 2000-2010 

(f) 25≤ hp <50 and pre-1999 

(g) 25≤ hp <50 and 1999-2003 

(h) 25≤ hp <50 and 2004-2010 

(i) 50≤ hp < 100 and pre-2004 

(j) 50≤ hp < 100 and 2004-2010 

(k) 100≤ hp < 174 and pre-2003 

(l) 100≤ hp < 174 and 2003-2010 

(m) 174≤ hp < 301 and pre-1996 

(n) 174≤ hp < 301 and 1996-2002 

(o) 174≤ hp < 301 and 2003-2010 

(p) 301≤ hp < 603 and pre-1996 

(q) 301≤ hp < 603 and 1996-2000 

(r) 301≤ hp < 603 and 2001-2010 

(s) 603≤ hp < 750 and pre-1996 

(t) 603≤ hp < 750 and 1996-2001 

(u) 603≤ hp < 750 and 2002-2010 

(v) > 750 hp and pre-2000 

(w) > 750 hp and 2001-2010 

iv) Finally, within each Horsepower/Model Year group, divide your vehicles based on the type 

of retrofit technology that will be applied (i.e. Engine Replacement, Engine repower, Hybrid 

Replacement, etc.)
Page 27 of 27

Reference Links: 

1. On-Highway Heavy Duty Compression Ignition Exhaust Certification Emission Standards 

www.epa.gov/otaq/standards/heavy-duty/hdci-exhaust.htm

2. Non Road Compression Ignition Exhaust Emission Standards 

www.epa.gov/otaq/standards/nonroad/nonroadci.htm