Transportation and Climate
Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) Tool
EPA’s Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) is a full vehicle simulation tool which estimates the greenhouse gas (GHG) emissions from light-duty vehicle sources. It is a physics-based, forward-looking, full vehicle simulator, capable of simulating various vehicle types and powertrain technologies. Version 2.0 of the ALPHA model has been updated from the previous version to include more realistic vehicle behavior and now includes internal auditing of all energy flows in the model.
ALPHA is being used by EPA to inform the Midterm Evaluation of Light-duty Vehicle Standards for Model Years 2022-2025. The MTE will be conducted through a collaborative, data-driven, and transparent process. The documentation of ALPHA on this page is part of EPA’s commitment to transparency in the MTE process. ALPHA is an in-house vehicle simulation tool used by EPA, and is not intended to be a commercial product.
The ALPHA model shares an underlying structure with EPA's Greenhouse Gas Emissions Model (GEM) used for medium- and heavy-duty vehicle compliance calculations. ALPHA is under active development and the versions of the model presented below represent the state of the package at particular points in time.
NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.
ALPHA v2.0 Simulation Samples
EPA is using ALPHA simulation results to inform its on-going calibration of the Lumped Parameter Model (LPM), an EPA desktop computer application that estimates the effectiveness (CO2 Reduction) of various technology combinations. A subset of the numerous ALPHA simulation results being studied during the MTE process were identified as key simulations used to inform the calibration of the LPM.
- ALPHA v2.0 Simulation Samples (ZIP) (4MB) This file contains a series of ALPHA V2.0 simulations (as of 2016.07.07) of the same type used to inform the calibration of the Lumped Parameter Model. Running this version of ALPHA requires Matlab/Simulink with StateFlow 2014a. For convenience, a plaintext form of the workspace for each ALPHA run is provided in an m-file format. Further details are in the readme.txt file.
ALPHA v2.0 Peer Review
EPA engaged ICF International to perform a peer review of the ALPHA Full Vehicle Simulation Model. This peer review process was carried out under EPA’s peer review guidelines. The entire model and all subsystems were unlocked for complete transparency. A number of independent subject matter experts provided reviews and comments on the methodologies used in the model.
- ALPHA v2.0 Peer Review
This file contains the ICF peer review report for ALPHA v 2.0 and will be available soon.
- ALPHA v2.0 Peer Review (ZIP) (1.14MB)
This file contains the files provided to peer reviewers for ALPHA v2.0 (as of 2016.05.05). Running the peer reviewed version of ALPHA requires Matlab/Simulink with StateFlow 2014a. Further details are in the readme.txt file.
Publications Concerning ALPHA v2.0
Throughout the MTE process, EPA’s goal is to publish as much of our research as possible in peer-reviewed technical papers and journals. These publications describe in more detail the development and use of the ALPHA model.
- "Estimating GHG Reduction from Combinations of Current Best-Available and Future Powertrain and Vehicle Technologies for a Midsized Car Using EPA's ALPHA Model," SAE Technical Paper 2016-01-0910, 2016, doi:10.4271/2016-01-0910, Kargul, J., Moskalik, A., Barba, D., Newman, K., and Dekraker, P. (PDF) (16 pp, 1.0MB, May 4, 2016)
- "Modeling of a Conventional Mid-Size Car with CVT Using ALPHA and Comparable Powertrain Technologies," SAE Technical Paper 2016-01-1141, 2016, doi:10.4271/2016-01-1141, Newman, K., Doorlag, M., and Barba, D. (PDF) (13 pp, 1.0MB, May 4, 2016)
- "Investigating the Effect of Advanced Automatic Transmissions on Fuel Consumption Using Vehicle Testing and Modeling," SAE Int. J. Engines 9(3):2016, doi:10.4271/2016-01-1142, Moskalik, A., Hula, A., Barba, D., and Kargul, J. (PDF) (13 pp, 1.0MB, May 4, 2016)
- "Modeling the Effects of Transmission Gear Count, Ratio Progression, and Final Drive Ratio on Fuel Economy and Performance Using ALPHA," SAE Technical Paper 2016-01-1143, 2016, doi:10.4271/2016-01-1143, Newman, K. and Dekraker, P. (PDF) (16 pp, 2.0MB, May 6, 2016)
- "Development and Testing of an Automatic Transmission Shift Schedule Algorithm for Vehicle Simulation," SAE Int. J. Engines 8(3):2015, doi:10.4271/2015-01-1142, Newman, K., Kargul, J., and Barba, D. (PDF) (11 pp, 1.0MB, March 11, 2015)
- "Benchmarking and Modeling of a Conventional Mid-Size Car Using ALPHA," SAE Technical Paper 2015-01-1140, 2015, doi:10.4271/2015-01-1140, Newman, K., Kargul, J., and Barba, D. (PDF) (12 pp, 1.0MB, March 26, 2015)
Overview of Testing and Integration with Modeling
Through its National Center for Advanced Technology (NCAT), EPA has integrated benchmarking and modeling activities to ensure robust data.
- Presentation of EPA testing and modeling activities (PDF) (19 pp, 1.67MB, January 20, 2016) This presentation highlights EPA's benchmarking and modeling activities relating to light duty GHG emissions.
Engine Mapping Process Documents
Integrating test data and modeling results for engines into the ALPHA model requires a process for translating test results into a full map representing all phases of engine operation. The following documents explain the process for creating ALPHA engine maps for key engine packages.
- Process for Generating Engine Fuel Consumption Map: Ricardo Baseline Standard Car Engine Tier 2 Fuel (PDF) (10 pp, 297K, June 20, 2016)
- Process for Generating Engine Fuel Consumption Map: Chevy Malibu 2.5L I4 engine using Tier 3 fuel (PDF) (7 pp, 371K, June 20, 2016)
- Process for Generating Engine Fuel Consumption Map: Mazda SKYACTIV 2.0L engine using Tier 2 fuel (PDF) (7 pp, 297K, June 20, 2016)
- Process for Generating Engine Fuel Consumption Map: Ford F150 EcoBoost 2.7L Tier 2 Fuel (PDF) (7 pp, 436K, June 20, 2016)
- Process for Generating Engine Fuel Consumption Map: Future Atkinson Engine with Cooled EGR and Cylinder Deactivation (PDF) (11 pp, 618K, June 20, 2016)
- Process for Generating Engine Fuel Consumption Map: Ricardo Cooled EGR Boost 24-bar Standard Car Engine Tier 2 Fuel (PDF) (11 pp, 371K, June 20, 2016)
The initial version of ALPHA, used for off-cycle technology evaluations, is provided for historical purposes. The software is a freely-distributed, desktop computer based application, built on MATLAB/Simulink. EPA is no longer using this version of ALPHA.
The downloadable installation file below (in a zip format) contains the ALPHA v1.0 tool. The model documentation provides details on how to launch and run the simulation tool.
- ALPHA User's Guide for Off-Cycle Credit Evaluation v1.0 (PDF) (22 pp, 1.27MB, EPA-420-B-12-051, August 2012) This document contains descriptions of how to launch and use the ALPHA tool for off-cycle technology evaluation.
- ALPHA v1.0 Installation File (ZIP) (198K) This file contains the ALPHA v1.0 application files written in MATLAB/Simulink. This version was used in EPA’s Model Year 2017-2025 Final Rulemaking for Light-Duty Vehicle Greenhouse Gas Emission Standards.