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Dr. Georgios Fontaras
Joint Research Centre, European Commission, 21027 Ispra, Italy

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Research Keywords & Expertise

0 Environmental Policy
0 Internal Combustion Engines
0 Vehicle energy efficiency
0 Transport energy and environmental impact
0 Vehicle emissions modeling

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Journal article
Published: 26 March 2021 in Applied Thermal Engineering
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Waste Heat Recovery (WHR) by means of an Organic Rankine Cycle is a technology often proposed to reduce the fuel consumption and CO2 emissions of heavy-duty vehicles. A Class 5 Heavy Lorry (tractor) with a WHR system was measured over various driving cycles on the chassis dyno and under realistic conditions on the road, performing each test-cycle with WHR enabled and disabled. The use of WHR lead to reductions in fuel consumption of 3.1% over the World Harmonized Vehicle Cycle, 2.5% over the Regional Delivery Cycle (RDC) and 1.9% over the on-road trips. The WHR system was able to produce more power output during the RDC on the chassis dyno compared to the on-road trips, as more exhaust energy was available during the RDC, resulting in a more considerable reduction of the fuel consumption. No statistically significant reduction of the pollutant emissions was observed. On-road trips were simulated with the Vehicle Energy Consumption calculation Tool, (VECTO), and the fuel consumption was predicted with an error of less than 1.5% for the individual trips and less than 0.5% when averaged over the different repetitions. These findings demonstrate the capability of VECTO to accurately simulate vehicles with Waste Heat Recovery under realistic conditions on the road.

ACS Style

Stijn Broekaert; Theodoros Grigoratos; Dimitrios Savvidis; Georgios Fontaras. Assessment of waste heat recovery for heavy-duty vehicles during on-road operation. Applied Thermal Engineering 2021, 191, 116891 .

AMA Style

Stijn Broekaert, Theodoros Grigoratos, Dimitrios Savvidis, Georgios Fontaras. Assessment of waste heat recovery for heavy-duty vehicles during on-road operation. Applied Thermal Engineering. 2021; 191 ():116891.

Chicago/Turabian Style

Stijn Broekaert; Theodoros Grigoratos; Dimitrios Savvidis; Georgios Fontaras. 2021. "Assessment of waste heat recovery for heavy-duty vehicles during on-road operation." Applied Thermal Engineering 191, no. : 116891.

Journal article
Published: 25 March 2021 in Transportation Research Part D: Transport and Environment
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Certification and monitoring of heavy vehicle CO2 emissions in several countries are based on individual vehicle simulation. Smaller fleet subsets can be used for accurate fleet-level results while preserving the characteristics of the underlying fleet-emissions distributions. The paper focuses on three approaches to capture fleet CO2 emissions: a) sampling directly from the fleet-data, b) sampling from data of individual vehicle components and c) using key statistics regarding the fleet composition that are available. The first and second approach deliver marginal divergences of the mean, between 1.1 and 2.1% and below 2.7 respectively, preserving the characteristics of the distribution. The third deviated by up to 5%, but lacked the detailed characteristics of the underlying statistical distribution. All three are useful when setting up fleet-wide monitoring schemes where detailed data are not available and to investigate the potential CO2 savings of various future fleet compositions, and scenarios regarding the diffusion of different types of technologies.

ACS Style

Nikiforos Zacharof; Georgios Fontaras; Biagio Ciuffo; Alessandro Tansini; Iker Prado-Rujas. An estimation of heavy-duty vehicle fleet CO2 emissions based on sampled data. Transportation Research Part D: Transport and Environment 2021, 94, 102784 .

AMA Style

Nikiforos Zacharof, Georgios Fontaras, Biagio Ciuffo, Alessandro Tansini, Iker Prado-Rujas. An estimation of heavy-duty vehicle fleet CO2 emissions based on sampled data. Transportation Research Part D: Transport and Environment. 2021; 94 ():102784.

Chicago/Turabian Style

Nikiforos Zacharof; Georgios Fontaras; Biagio Ciuffo; Alessandro Tansini; Iker Prado-Rujas. 2021. "An estimation of heavy-duty vehicle fleet CO2 emissions based on sampled data." Transportation Research Part D: Transport and Environment 94, no. : 102784.

Journal article
Published: 19 January 2021 in Sustainability
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A vehicle’s air drag coefficient (Cd) and rolling resistance coefficient (RRC) have a significant impact on its fuel consumption. Consequently, these properties are required as input for the certification of the vehicle’s fuel consumption and Carbon Dioxide emissions, regardless of whether the certification is done via simulation or chassis dyno testing. They can be determined through dedicated measurements, such as a drum test for the tire’s rolling resistance coefficient and constant speed test (EU) or coast down test (US) for the body’s air Cd. In this paper, a methodology that allows determining the vehicle’s Cd∙A (the product of Cd and frontal area of the vehicle) from on-road tests is presented. The possibility to measure these properties during an on-road test, without the need for a test track, enables third parties to verify the certified vehicle properties in order to preselect vehicle for further regulatory testing. On-road tests were performed with three heavy-duty vehicles, two lorries, and a coach, over different routes. Vehicles were instrumented with wheel torque sensors, wheel speed sensors, a GPS device, and a fuel flow sensor. Cd∙A of each vehicle is determined from the test data with the proposed methodology and validated against their certified value. The methodology presents satisfactory repeatability with the error ranging from −21 to 5% and averaging approximately −6.8%. A sensitivity analysis demonstrates the possibility of using the tire energy efficiency label instead of the measured RRC to determine the air drag coefficient. Finally, on-road tests were simulated in the Vehicle Energy Consumption Calculation Tool with the obtained parameters, and the average difference in fuel consumption was found to be 2%.

ACS Style

Dimitrios Komnos; Stijn Broekaert; Theodoros Grigoratos; Leonidas Ntziachristos; Georgios Fontaras. In Use Determination of Aerodynamic and Rolling Resistances of Heavy-Duty Vehicles. Sustainability 2021, 13, 974 .

AMA Style

Dimitrios Komnos, Stijn Broekaert, Theodoros Grigoratos, Leonidas Ntziachristos, Georgios Fontaras. In Use Determination of Aerodynamic and Rolling Resistances of Heavy-Duty Vehicles. Sustainability. 2021; 13 (2):974.

Chicago/Turabian Style

Dimitrios Komnos; Stijn Broekaert; Theodoros Grigoratos; Leonidas Ntziachristos; Georgios Fontaras. 2021. "In Use Determination of Aerodynamic and Rolling Resistances of Heavy-Duty Vehicles." Sustainability 13, no. 2: 974.

Journal article
Published: 21 December 2020 in Transportation Research Part D: Transport and Environment
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European Union (EU) regulations setting CO2 emission standards for light-duty (LDV) and heavy-duty vehicles (HDVs) require the Commission to monitor in-use fuel consumption (FC) using on-board fuel consumption monitoring (OBFCM) devices. For LDVs, the accuracy to measure fuel consumed is set by regulation to ±5%, while for HDVs no requirements exist so far. In this study, OBFCM data from 15 LDVs and 12 HDVs were recorded in lab and on-road trips. Results indicate that the fuel consumed measured by the OBFCM, for the majority of the vehicles, satisfies the accuracy requirements of ±5% over complete laboratory tests or complete on-road trips (maximum vehicle average uncertainty ~7%). Statistical analysis showed that on-board diagnostics (OBD) accuracy can be impacted by the average vehicle speed, acceleration, and overall trip dynamicity. The lowest accuracy can be expected when vehicles are driven at low speeds under transient conditions. For most of the vehicles the distance calculated from the OBD speed signal has an accuracy within ±1.5% on-road when Global Positioning System (GPS) distance is used as a reference. Both HDV and LDV results, confirmed that OBD accuracy and precision in measuring fuel consumed and distance improved for monitoring over longer periods (complete trips vs short phases). The results of this study could be used to further support the standardization of OBFCM accuracy in vehicles, and the setup of the EU real-world CO2 emissions monitoring approach.

ACS Style

J. Pavlovic; G. Fontaras; S. Broekaert; B. Ciuffo; M.A. Ktistakis; T. Grigoratos. How accurately can we measure vehicle fuel consumption in real world operation? Transportation Research Part D: Transport and Environment 2020, 90, 102666 .

AMA Style

J. Pavlovic, G. Fontaras, S. Broekaert, B. Ciuffo, M.A. Ktistakis, T. Grigoratos. How accurately can we measure vehicle fuel consumption in real world operation? Transportation Research Part D: Transport and Environment. 2020; 90 ():102666.

Chicago/Turabian Style

J. Pavlovic; G. Fontaras; S. Broekaert; B. Ciuffo; M.A. Ktistakis; T. Grigoratos. 2020. "How accurately can we measure vehicle fuel consumption in real world operation?" Transportation Research Part D: Transport and Environment 90, no. : 102666.

Journal article
Published: 15 September 2020 in Transportation Research Procedia
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The European Commission’s Joint Research Centre, in line with the European Strategy for Low-Emission Mobility, has launched in 2016 the Green Driving Tool, an interactive web-based tool aiming at estimating fuel costs and CO2 emissions of individual car journeys. In parallel, it has developed U-SAVE, a routing system for fuel-efficient trip planning aiming at fuel consumption minimization and vehicle specific calibration. This paper provides a first assessment of the performance of the two tools in predicting fuel consumption and CO2 emissions over real-world trips. The analysis focused on the accuracy and uncertainty of the two tools when varying the detail of vehicle input data and of the velocity profile used in the calculation. These elements are particularly important in case of future integration of the tools with traffic simulation models where the level of detail regarding the vehicle input or the speed profile may vary. Results show that U-SAVE prediction is positively affected by the detail of vehicle specifications, while is not significantly sensitive to the detail of the velocity profile. Contrary, Green Driving didn’t show any remarkable change when varying both parameters. Overall, U-SAVE demonstrates a good performance in predicting CO2 emissions over on-road tests reaching an average prediction accuracy over an entire test trip of -4.6% and a standard deviation of 5.2%, while Green Driving exhibit higher uncertainty (on average 12%) but lower bias which ranged in the order of 0 to +3% depending on the vehicle and the test trip considered.

ACS Style

Caterina Mogno; Vincenzo Arcidiacono; Biagio Ciuffo; Lorenzo Maineri; Michail Makridis; Jelica Pavlovic; Stefanos Tsiakmakis; Georgios Fontaras. Tools for Customized Consumer Information on Vehicle Energy Consumption and Costs - A European Case Study. Transportation Research Procedia 2020, 48, 1493 -1504.

AMA Style

Caterina Mogno, Vincenzo Arcidiacono, Biagio Ciuffo, Lorenzo Maineri, Michail Makridis, Jelica Pavlovic, Stefanos Tsiakmakis, Georgios Fontaras. Tools for Customized Consumer Information on Vehicle Energy Consumption and Costs - A European Case Study. Transportation Research Procedia. 2020; 48 ():1493-1504.

Chicago/Turabian Style

Caterina Mogno; Vincenzo Arcidiacono; Biagio Ciuffo; Lorenzo Maineri; Michail Makridis; Jelica Pavlovic; Stefanos Tsiakmakis; Georgios Fontaras. 2020. "Tools for Customized Consumer Information on Vehicle Energy Consumption and Costs - A European Case Study." Transportation Research Procedia 48, no. : 1493-1504.

Journal article
Published: 13 January 2020 in Transport Policy
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A vehicle simulation model, CO2MPAS supports the introduction of the new WLTP-based certification system for CO2 emissions in Europe. This paper investigates the possibility to use the underlying simulation methodology to accurately calculate CO2 emissions over real-world trips, thus to extend the use of the methodology beyond vehicle certification. As a reference, the analysis used measurement data obtained from four vehicles over two different routes under real-world driving conditions. The CO2 emissions were measured using portable emissions measurement systems. The formal CO2MPAS methodology and two modified versions of it that require a reduced number of input data were assessed about their capacity to predict the measured CO2 emissions. The analysis focused on the accuracy and uncertainty of the three different methodology configurations. As an additional benchmark, the analysis considered the CO2 emissions estimates obtained from the EMEP/EEA Guidebook methodology used for emissions inventorying in Europe. Results show that the basic CO2MPAS configuration demonstrates good performance in predicting CO2 emissions over on-road tests, reaching a prediction accuracy over an entire test trip of −0,3% and a standard deviation of 3,1%. The modified versions showed slightly higher biases up to 3% and uncertainties (5–7%), but remaining within reasonable limits considering the reduced number of inputs used in each case. Given its ability to predict CO2 emissions accurately on a local base, CO2MPAS could be used for the prediction of instantaneous CO2 emissions in traffic micro-simulation exercises.

ACS Style

Caterina Mogno; Georgios Fontaras; Vincenzo Arcidiacono; Dimitrios Komnos; Jelica Pavlovic; Biagio Ciuffo; Michail Makridis; Victor Valverde. The application of the CO2MPAS model for vehicle CO2 emissions estimation over real traffic conditions. Transport Policy 2020, 1 .

AMA Style

Caterina Mogno, Georgios Fontaras, Vincenzo Arcidiacono, Dimitrios Komnos, Jelica Pavlovic, Biagio Ciuffo, Michail Makridis, Victor Valverde. The application of the CO2MPAS model for vehicle CO2 emissions estimation over real traffic conditions. Transport Policy. 2020; ():1.

Chicago/Turabian Style

Caterina Mogno; Georgios Fontaras; Vincenzo Arcidiacono; Dimitrios Komnos; Jelica Pavlovic; Biagio Ciuffo; Michail Makridis; Victor Valverde. 2020. "The application of the CO2MPAS model for vehicle CO2 emissions estimation over real traffic conditions." Transport Policy , no. : 1.

Original research article
Published: 24 September 2019 in Frontiers in Mechanical Engineering
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Heavy-duty vehicles constitute a significant contributor to road CO2 emissions, despite accounting for only a low share of the vehicle fleet. CO2 Emissions certification and monitoring are performed using vehicle simulation software designed for the purpose (VECTO). The European Union currently regulates rigid truck and tractor-trailer CO2 emissions and subsequently will proceed to buses and other heavy-duty vehicle categories. The current study investigated the use of VECTO on a city bus by modeling the on-road operating conditions of a vehicle in an urban route in Istanbul. The simulation results for constant auxiliary load showed a difference with the on-road measurements in the range of −1.6 to 3.2%, depending on the direction of the route. The difference was attributed to the influence of the total elevation change, and the use of auxiliaries. The latter comprise a significant part of energy consumption in buses, and for this reason, VECTO includes a dedicated bus auxiliary module. The use of the module was also explored, and it was found to improve the results in some cases. The findings highlight the need to assess the operation of auxiliary components in city buses accurately, and to consider the provision of more precise, auxiliary-component specific, information when running actual real-world CO2 simulations of these vehicles.

ACS Style

Nikiforos Zacharof; Orkun Özener; Muammer Özkan; Abdullah Kilicaslan; Georgios Fontaras. Simulating City-Bus On-Road Operation With VECTO. Frontiers in Mechanical Engineering 2019, 5, 1 .

AMA Style

Nikiforos Zacharof, Orkun Özener, Muammer Özkan, Abdullah Kilicaslan, Georgios Fontaras. Simulating City-Bus On-Road Operation With VECTO. Frontiers in Mechanical Engineering. 2019; 5 ():1.

Chicago/Turabian Style

Nikiforos Zacharof; Orkun Özener; Muammer Özkan; Abdullah Kilicaslan; Georgios Fontaras. 2019. "Simulating City-Bus On-Road Operation With VECTO." Frontiers in Mechanical Engineering 5, no. : 1.

Journal article
Published: 02 May 2019 in Atmosphere
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Tailpipe emissions of a pool of 13 Euro 6b light-duty vehicles (eight diesel and five gasoline-powered) were measured over an extensive experimental campaign that included laboratory (chassis dynamometer), and on-road tests (using a portable emissions measurement system). The New European Driving Cycle (NEDC) and the Worldwide harmonised Light-duty vehicles Test Cycle (WLTC) were driven in the laboratory following standard and extended testing procedures (such as low temperatures, use of auxiliaries, modified speed trace). On-road tests were conducted in real traffic conditions, within and outside the boundary conditions of the regulated European Real-Driving Emissions (RDE) test. Nitrogen oxides (NOX), particle number (PN), carbon monoxide (CO), total hydrocarbons (HC), and carbon dioxide (CO2) emission factors were developed considering the whole cycles, their sub-cycles, and the first 300 s of each test to assess the cold start effect. Despite complying with the NEDC type approval NOX limit, diesel vehicles emitted, on average, over the WLTC and the RDE 2.1 and 6.7 times more than the standard limit, respectively. Diesel vehicles equipped with only a Lean NOX trap (LNT) averaged six and two times more emissions over the WLTC and the RDE, respectively, than diesel vehicles equipped with a selective catalytic reduction (SCR) catalyst. Gasoline vehicles with direct injection (GDI) emitted eight times more NOX than those with port fuel injection (PFI) on RDE tests. Large NOX emissions on the urban section were also recorded for GDIs (122 mg/km). Diesel particle filters were mounted on all diesel vehicles, resulting in low particle number emission (~1010 #/km) over all testing conditions including low temperature and high dynamicity. GDIs (~1012 #/km) and PFIs (~1011 #/km) had PN emissions that were, on average, two and one order of magnitude higher than for diesel vehicles, respectively, with significant contribution from the cold start. PFIs yielded high CO emission factors under high load operation reaching on average 2.2 g/km and 3.8 g/km on WLTC extra-high and RDE motorway, respectively. The average on-road CO2 emissions were ~33% and 41% higher than the declared CO2 emissions at type-approval for diesel and gasoline vehicles, respectively. The use of auxiliaries (AC and lights on) over the NEDC led to an increase of ~20% of CO2 emissions for both diesel and gasoline vehicles. Results for NOX, CO and CO2 were used to derive average on-road emission factors that are in good agreement with the emission factors proposed by the EMEP/EEA guidebook.

ACS Style

Victor Valverde; Bernat Mora; Michaël Clairotte; Jelica Pavlovic; Ricardo Suarez-Bertoa; Barouch Giechaskiel; Covadonga Astorga-Llorens; Georgios Fontaras. Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements. Atmosphere 2019, 10, 243 .

AMA Style

Victor Valverde, Bernat Mora, Michaël Clairotte, Jelica Pavlovic, Ricardo Suarez-Bertoa, Barouch Giechaskiel, Covadonga Astorga-Llorens, Georgios Fontaras. Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements. Atmosphere. 2019; 10 (5):243.

Chicago/Turabian Style

Victor Valverde; Bernat Mora; Michaël Clairotte; Jelica Pavlovic; Ricardo Suarez-Bertoa; Barouch Giechaskiel; Covadonga Astorga-Llorens; Georgios Fontaras. 2019. "Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements." Atmosphere 10, no. 5: 243.

Journal article
Published: 01 February 2019 in Energy
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ACS Style

Stefanos Tsiakmakis; Georgios Fontaras; Jan Dornoff; Victor Valverde; Dimitrios Komnos; Biagio Ciuffo; Peter Mock; Zissis Samaras. From lab-to-road & vice-versa: Using a simulation-based approach for predicting real-world CO2 emissions. Energy 2019, 169, 1153 -1165.

AMA Style

Stefanos Tsiakmakis, Georgios Fontaras, Jan Dornoff, Victor Valverde, Dimitrios Komnos, Biagio Ciuffo, Peter Mock, Zissis Samaras. From lab-to-road & vice-versa: Using a simulation-based approach for predicting real-world CO2 emissions. Energy. 2019; 169 ():1153-1165.

Chicago/Turabian Style

Stefanos Tsiakmakis; Georgios Fontaras; Jan Dornoff; Victor Valverde; Dimitrios Komnos; Biagio Ciuffo; Peter Mock; Zissis Samaras. 2019. "From lab-to-road & vice-versa: Using a simulation-based approach for predicting real-world CO2 emissions." Energy 169, no. : 1153-1165.

Journal article
Published: 10 January 2019 in Atmospheric Environment
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Despite that Heavy-Duty Vehicles (HDVs) represent a small part of the overall vehicle population they have been identified as one of the most important contributors to air pollution. This is one of the reasons why HDV emissions regulations are becoming more and more stringent worldwide. Following this trend, Europe introduced the Euro VI standard which includes more stringent emission limits for hydrocarbons, PM and NOx, while for the first time a limit for solid PN emissions was set. At the same time increased concern regarding greenhouse gas emissions led to a series of initiatives including HDVs CO2 certification and monitoring with the latest being the submission of a proposal for CO2 emission targets for 2025 and 2030. Despite the general concern, published data regarding Euro VI HDV emissions are scarce, while real-world emission factor measurements of regulated and unregulated pollutants are even more difficult to find. The main objective of this paper is to present real-world diesel Euro VI HDVs emissions of both gaseous pollutants and solid PN. For that reason five HDVs, including four trucks and one bus, were tested on-road under typical driving conditions. A breakdown of the emissions to low, medium, and high speed conditions was also performed with the aim investigating the performance of aftertreatment systems under different speed conditions. All tested vehicles performed better compared to older technology diesel HDVs, thus reflecting the technological improvements introduced over the last years. However, relatively high emissions were observed for some of the pollutants over low speed phases due to reduced effectiveness of the corresponding emission control systems. Calculated emission factors were also compared to existing emission inventories and good correlation was found for NOx, CO2 and solid PN emissions.

ACS Style

Theodoros Grigoratos; Georgios Fontaras; Barouch Giechaskiel; Nikiforos Zacharof. Real world emissions performance of heavy-duty Euro VI diesel vehicles. Atmospheric Environment 2019, 201, 348 -359.

AMA Style

Theodoros Grigoratos, Georgios Fontaras, Barouch Giechaskiel, Nikiforos Zacharof. Real world emissions performance of heavy-duty Euro VI diesel vehicles. Atmospheric Environment. 2019; 201 ():348-359.

Chicago/Turabian Style

Theodoros Grigoratos; Georgios Fontaras; Barouch Giechaskiel; Nikiforos Zacharof. 2019. "Real world emissions performance of heavy-duty Euro VI diesel vehicles." Atmospheric Environment 201, no. : 348-359.

Journal article
Published: 11 December 2018 in Transportation Research Part D: Transport and Environment
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Decreasing road transport's harmful effects on environment and health and reducing road accidents are major policy priorities. A variety of technologies could drastically improve air quality, reduce energy consumption and CO2 emissions of road vehicles: in this respect, a prominent trend leverages Electric Vehicles (EVs), supported by improved performance and energy efficiency through connectivity and automation. A noteworthy research question in the transition from Internal Combustion Engine Vehicles (ICEVs) to the alternative technologies, is to understand how Intelligent Transport Systems and other traffic-related measures can contribute to the reduction of fuel consumption and greenhouse gas emissions. In fact, a widely acknowledged tenet assumes that congestion removal or mitigation in presence of ICEVs implies also a reduction of transport-related externalities. This paper explores whether this effect still holds for EVs, by performing an analysis of energy consumption over different vehicle trajectories, under both congested and free-flow conditions. Calculations are carried out using two vehicle simulators: the VT-CPEM (Virginia Tech Comprehensive Power-based Energy consumption model) model for EVs and the CO2MPAS (CO2 model for Passenger and commercial vehicle Simulation) vehicle simulator for the ICEVs, for both electric and conventional cases passengers and freight/commercial powertrains have been analysed. Results are presented on real and simulated data related to four powertrain-vehicle combinations, in terms of general trends of energy/fuel consumption versus speed. Interestingly, results show that, differently from ICEVs, the relationship between congestion and energy consumption underlying EVs can change with higher energy consumption connected to an increased average traffic speed.

ACS Style

Chiara Fiori; Vincenzo Arcidiacono; Georgios Fontaras; Michail Makridis; Konstantinos Mattas; Vittorio Marzano; Christian Thiel; Biagio Ciuffo. The effect of electrified mobility on the relationship between traffic conditions and energy consumption. Transportation Research Part D: Transport and Environment 2018, 67, 275 -290.

AMA Style

Chiara Fiori, Vincenzo Arcidiacono, Georgios Fontaras, Michail Makridis, Konstantinos Mattas, Vittorio Marzano, Christian Thiel, Biagio Ciuffo. The effect of electrified mobility on the relationship between traffic conditions and energy consumption. Transportation Research Part D: Transport and Environment. 2018; 67 ():275-290.

Chicago/Turabian Style

Chiara Fiori; Vincenzo Arcidiacono; Georgios Fontaras; Michail Makridis; Konstantinos Mattas; Vittorio Marzano; Christian Thiel; Biagio Ciuffo. 2018. "The effect of electrified mobility on the relationship between traffic conditions and energy consumption." Transportation Research Part D: Transport and Environment 67, no. : 275-290.

Journal article
Published: 11 October 2018 in IEEE Transactions on Intelligent Transportation Systems
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Microscopic traffic simulation models are widely used to assess the impact of measures and technologies on the road transportation system. The assessment usually involves several measures of performance, such as overall traffic conditions, travel time, energy demand/fuel consumption, emissions, and safety. In doing so, it is usually assumed that traffic models are able to capture not only traffic dynamics but also vehicle dynamics (especially to compute energy/fuel consumption, emissions, and safety). However, this is not necessarily the case with the possibility of achieving unreliable outcomes when extrapolating from traffic to measures of performance related to the vehicle dynamics. The objective of the present paper is to assess the capability of existing car-following models to reproduce observed vehicle acceleration dynamics. A set of experiments was carried out in the Vehicle Emissions Laboratories of the European Commission Joint Research Centre in order to generate relevant data sets. These experiments are used to test the performance of three well-known car-following models. Although all models have been largely tested against their capability to correctly reproduce traffic dynamics, the findings raise concerns about their capability (and thus of the traffic models using them) to predict the effect on the microscopic vehicle dynamics and thus on emissions and energy/fuel consumption. The results of the present work can be considered valid beyond the analyzed car-following models, as simple acceleration rules are usually assumed in the vast majority of the traffic simulation frameworks. Consequently, it can be concluded that there is a number.

ACS Style

Biagio Ciuffo; Michail Makridis; Tomer Toledo; Georgios Fontaras. Capability of Current Car-Following Models to Reproduce Vehicle Free-Flow Acceleration Dynamics. IEEE Transactions on Intelligent Transportation Systems 2018, 19, 3594 -3603.

AMA Style

Biagio Ciuffo, Michail Makridis, Tomer Toledo, Georgios Fontaras. Capability of Current Car-Following Models to Reproduce Vehicle Free-Flow Acceleration Dynamics. IEEE Transactions on Intelligent Transportation Systems. 2018; 19 (11):3594-3603.

Chicago/Turabian Style

Biagio Ciuffo; Michail Makridis; Tomer Toledo; Georgios Fontaras. 2018. "Capability of Current Car-Following Models to Reproduce Vehicle Free-Flow Acceleration Dynamics." IEEE Transactions on Intelligent Transportation Systems 19, no. 11: 3594-3603.

Journal article
Published: 01 September 2018 in Applied Energy
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As of July 2017, the emissions type-approval of light-duty vehicles in Europe is based on the Worldwide Harmonized Light-duty vehicles Test Procedure (WLTP), introduced to replace the old and outdated New European Driving Cycle (NEDC) test procedure. Since some elements of the European Legislation are still based on the NEDC (2020 CO2 emission targets, vehicle labelling, national vehicle taxation policies, etc.) in order to allow sufficient lead time to vehicle manufacturers and national authorities to adapt to the new procedure, a simulation-based approach was chosen to calculate CO2 emissions and fuel consumption according to the NEDC regime in the period 2017–2020. To achieve this objective without significantly increasing the cost and duration of the certification procedure, existing regulation foresees that vehicles are tested over the WLTP for CO2 emissions, the test results are used as input in a simulation model that then calculates the corresponding CO2 according to the NEDC test protocol. A dedicated vehicle simulation model (CO2MPAS) was developed for the purpose and is currently used for the type-approval of new vehicles in Europe. The development specifications of CO2MPAS were challenging, as it had to be highly accurate, exhibit fast operation, and function with a limited number of input data. This paper presents the development principles and process followed, details of the physical models employed in CO2MPAS, and provides information regarding its accuracy, validity and in use operation. CO2MPAS achieves low errors in the prediction of the NEDC cycle that in the controlled sample used for its development are of the order of 1% with a standard deviation of 3%, while the respective in-use numbers are of the order of 1.5% and 5%. In parallel, random sampling and testing of a 10% of the type-approved vehicles also occurs in order to guarantee the quality of the CO2MPAS results and the validity of the process. It is concluded that CO2MPAS can be used to accurately estimate emissions of conventional vehicles within a ±4% accuracy range, even when limited input data are available. In addition, the in-use data analyzed suggest that the use of the tool enables the certification of about 2/3 of the new vehicle models without the need of additional experimental tests. This is an important achievement as it reduces the costs and time necessary to certify light-duty vehicle CO2 emissions during the transitional period. Finally, it can be concluded that the use of CO2MPAS does not affect the declared CO2 emissions of vehicles over NEDC conditions.

ACS Style

Georgios Fontaras; Víctor Valverde; Vincenzo Arcidiacono; Stefanos Tsiakmakis; Konstantinos Anagnostopoulos; Dimitrios Komnos; Jelica Pavlovic; Biagio Ciuffo. The development and validation of a vehicle simulator for the introduction of Worldwide Harmonized test protocol in the European light duty vehicle CO2 certification process. Applied Energy 2018, 226, 784 -796.

AMA Style

Georgios Fontaras, Víctor Valverde, Vincenzo Arcidiacono, Stefanos Tsiakmakis, Konstantinos Anagnostopoulos, Dimitrios Komnos, Jelica Pavlovic, Biagio Ciuffo. The development and validation of a vehicle simulator for the introduction of Worldwide Harmonized test protocol in the European light duty vehicle CO2 certification process. Applied Energy. 2018; 226 ():784-796.

Chicago/Turabian Style

Georgios Fontaras; Víctor Valverde; Vincenzo Arcidiacono; Stefanos Tsiakmakis; Konstantinos Anagnostopoulos; Dimitrios Komnos; Jelica Pavlovic; Biagio Ciuffo. 2018. "The development and validation of a vehicle simulator for the introduction of Worldwide Harmonized test protocol in the European light duty vehicle CO2 certification process." Applied Energy 226, no. : 784-796.

Research article
Published: 14 March 2018 in Transportation Research Record: Journal of the Transportation Research Board
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There is increasing evidence suggesting that real-world fuel consumption and CO2 improvements in the last decade have been much less than those measured during type-approval tests. Scientific studies have found that the offset between officially reported values and real-world vehicle CO2 emissions in Europe has constantly increased over the last years. The difference between officially reported and actual CO2 emissions of vehicles has three main implications: (i) it undermines the effectiveness of CO2 regulations in reducing greenhouse gas emissions in Europe; (ii) it distorts competition between vehicle manufacturers; (iii) it undermines innovation. As a fundamental step to deal with this issue, the European Commission has already replaced the old and outdated test procedure used so far in the emission type-approval of vehicles with the worldwide harmonized light vehicles test procedure (WLTP). Being a lab-based test procedure, the WLTP, by its nature, can only cover part of the CO2 gap. There is therefore increasing pressure to integrate the current type-approval system with additional measures based on real-world measurements. One of the options under discussion is to use the CO2 emissions measured during the real driving emission test. The objective of the present paper is to assess the validity of this proposal and to propose other possible ways to deal with the CO2/fuel consumption gap. In particular, the paper presents experimental evidence on the variability of the CO2/fuel consumption of a vehicle, questioning the idea that a single central estimate of these quantities may be sufficient.

ACS Style

Jelica Pavlovic; Konstantinos Anagnostopoulos; Michaël Clairotte; Vincenzo Arcidiacono; Georgios Fontaras; Iker Prado Rujas; Victor Valverde Morales; Biagio Ciuffo. Dealing with the Gap between Type-Approval and In-Use Light Duty Vehicles Fuel Consumption and CO2 Emissions: Present Situation and Future Perspective. Transportation Research Record: Journal of the Transportation Research Board 2018, 2672, 23 -32.

AMA Style

Jelica Pavlovic, Konstantinos Anagnostopoulos, Michaël Clairotte, Vincenzo Arcidiacono, Georgios Fontaras, Iker Prado Rujas, Victor Valverde Morales, Biagio Ciuffo. Dealing with the Gap between Type-Approval and In-Use Light Duty Vehicles Fuel Consumption and CO2 Emissions: Present Situation and Future Perspective. Transportation Research Record: Journal of the Transportation Research Board. 2018; 2672 (2):23-32.

Chicago/Turabian Style

Jelica Pavlovic; Konstantinos Anagnostopoulos; Michaël Clairotte; Vincenzo Arcidiacono; Georgios Fontaras; Iker Prado Rujas; Victor Valverde Morales; Biagio Ciuffo. 2018. "Dealing with the Gap between Type-Approval and In-Use Light Duty Vehicles Fuel Consumption and CO2 Emissions: Present Situation and Future Perspective." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 2: 23-32.

Journal article
Published: 13 October 2017 in Energies
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Although Hybrid Electric Vehicles (HEVs) represent one of the key technologies to reduce CO2 emissions, their effective potential in real world driving conditions strongly depends on the performance of their Energy Management System (EMS) and on its capability to maximize the efficiency of the powertrain in real life as well as during Type Approval (TA) tests. Attempting to close the gap between TA and real world CO2 emissions, the European Commission has decided to introduce from September 2017 the Worldwide Harmonized Light duty Test Procedure (WLTP), replacing the previous procedure based on the New European Driving Cycle (NEDC). The aim of this work is the analysis of the impact of different driving cycles and operating conditions on CO2 emissions and on energy management strategies of a Euro-6 HEV through the limited number of information available from the chassis dyno tests. The vehicle was tested considering different initial battery State of Charge (SOC), ranging from 40% to 65%, and engine coolant temperatures, from −7 °C to 70 °C. The change of test conditions from NEDC to WLTP was shown to lead to a significant reduction of the electric drive and to about a 30% increase of CO2 emissions. However, since the specific energy demand of WLTP is about 50% higher than that of NEDC, these results demonstrate that the EMS strategies of the tested vehicle can achieve, in test conditions closer to real life, even higher efficiency levels than those that are currently evaluated on the NEDC, and prove the effectiveness of HEV technology to reduce CO2 emissions.

ACS Style

Claudio Cubito; Federico Millo; Giulio Boccardo; Giuseppe Di Pierro; Biagio Ciuffo; Georgios Fontaras; Simone Serra; Marcos Otura Garcia; Germana Trentadue. Impact of Different Driving Cycles and Operating Conditions on CO2 Emissions and Energy Management Strategies of a Euro-6 Hybrid Electric Vehicle. Energies 2017, 10, 1590 .

AMA Style

Claudio Cubito, Federico Millo, Giulio Boccardo, Giuseppe Di Pierro, Biagio Ciuffo, Georgios Fontaras, Simone Serra, Marcos Otura Garcia, Germana Trentadue. Impact of Different Driving Cycles and Operating Conditions on CO2 Emissions and Energy Management Strategies of a Euro-6 Hybrid Electric Vehicle. Energies. 2017; 10 (10):1590.

Chicago/Turabian Style

Claudio Cubito; Federico Millo; Giulio Boccardo; Giuseppe Di Pierro; Biagio Ciuffo; Georgios Fontaras; Simone Serra; Marcos Otura Garcia; Germana Trentadue. 2017. "Impact of Different Driving Cycles and Operating Conditions on CO2 Emissions and Energy Management Strategies of a Euro-6 Hybrid Electric Vehicle." Energies 10, no. 10: 1590.

Proceedings article
Published: 04 September 2017 in SAE Technical Paper Series
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ACS Style

Jelica Pavlovic; Alessandro Tansini; Georgios Fontaras; Biagio Ciuffo; Marcos Garcia Otura; Germana Trentadue; Ricardo Suarez Bertoa; Federico Millo. The Impact of WLTP on the Official Fuel Consumption and Electric Range of Plug-in Hybrid Electric Vehicles in Europe. SAE Technical Paper Series 2017, 1, 1 .

AMA Style

Jelica Pavlovic, Alessandro Tansini, Georgios Fontaras, Biagio Ciuffo, Marcos Garcia Otura, Germana Trentadue, Ricardo Suarez Bertoa, Federico Millo. The Impact of WLTP on the Official Fuel Consumption and Electric Range of Plug-in Hybrid Electric Vehicles in Europe. SAE Technical Paper Series. 2017; 1 ():1.

Chicago/Turabian Style

Jelica Pavlovic; Alessandro Tansini; Georgios Fontaras; Biagio Ciuffo; Marcos Garcia Otura; Germana Trentadue; Ricardo Suarez Bertoa; Federico Millo. 2017. "The Impact of WLTP on the Official Fuel Consumption and Electric Range of Plug-in Hybrid Electric Vehicles in Europe." SAE Technical Paper Series 1, no. : 1.

Journal article
Published: 01 August 2017 in Applied Energy
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Common approaches to assess the evolution of CO2 emissions from road vehicles are usually based on (a) estimates of future fleet composition, where most approaches consider vehicles at a rather aggregated level, and (b) emission factors, which are either based on CO2 certification data or statistically-provided functional relationships obtained from real world test data, or a combination of the two. This approach has certain limitations in capturing the effect of new technologies on CO2 emission related policy initiatives. The present study proposes a new method for the detailed calculation of the European light duty vehicle fleet CO2 emissions, which could help to overcome such limitations, achieve better results when making CO2 emissions projections and better support future policies. Simulation at individual vehicle level is combined with fleet composition data, retrieved from the official European CO2 emissions monitoring database, and publicly available data regarding individual vehicle characteristics in order to calculate vehicle CO2 emissions and fuel consumption over different conditions and vehicle configurations. The methodology is applied to analyse and assess the impact of the introduction of the new certification procedure, the Worldwide Light duty vehicle Test Procedure (WLTP), on the European car fleet CO2 emissions. Results show an average WLTP to NEDC CO2 emissions ratio of approximately 1.2. The increases in CO2 emissions are higher for cars exhibiting lower NEDC emission values (additional 29 and 25 gCO2/km for vehicles emitting 100 and 119 gCO2/km, respectively). At higher emission levels (about 250 CO2 g/km) WLTP and NEDC present comparable results. Three possible scenarios for the translation of projected NEDC CO2 emissions to WLTP-based ones are quantified.JRC.C.4-Sustainable Transpor

ACS Style

Stefanos Tsiakmakis; Georgios Fontaras; Biagio Ciuffo; Zissis Samaras. A simulation-based methodology for quantifying European passenger car fleet CO 2 emissions. Applied Energy 2017, 199, 447 -465.

AMA Style

Stefanos Tsiakmakis, Georgios Fontaras, Biagio Ciuffo, Zissis Samaras. A simulation-based methodology for quantifying European passenger car fleet CO 2 emissions. Applied Energy. 2017; 199 ():447-465.

Chicago/Turabian Style

Stefanos Tsiakmakis; Georgios Fontaras; Biagio Ciuffo; Zissis Samaras. 2017. "A simulation-based methodology for quantifying European passenger car fleet CO 2 emissions." Applied Energy 199, no. : 447-465.

Conference paper
Published: 01 June 2017 in 2017 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems (MT-ITS)
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Increasing penetration of connected and automated vehicles on the road, which is expected in the near future, could lead to a complete transformation of surface transport. From the political perspective, there is an increasing expectation that this transformation would help make transport systems more efficient from an economic, environmental and social perspective. Researchers in the traffic community are therefore called to follow this process and provide assessment tools able to capture the effect of such technologies. As a first step, since many new technologies have an impact on vehicle dynamics, traffic models should be able to better reproduce the microscopic vehicle behavior (and not only the behavior of the traffic). The present paper tries to contribute to this evolution by showing the limitations of different well-known car-following models in reproducing the vehicle acceleration dynamics. The findings raise concerns about the capability of current traffic models in assessing the effect on traffic and on the environment of technologies having an impact on the vehicle dynamics. They also highlight the need for a deeper integration of traffic and vehicle models in order to explicitly take into account the way in which vehicle technologies operate in their interaction with the driver.

ACS Style

Michail Makridis; Biagio Ciuffo; Georgios Fontaras; Tomer Toledo. Free flow acceleration: Humans and car-following models. 2017 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems (MT-ITS) 2017, 262 -267.

AMA Style

Michail Makridis, Biagio Ciuffo, Georgios Fontaras, Tomer Toledo. Free flow acceleration: Humans and car-following models. 2017 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems (MT-ITS). 2017; ():262-267.

Chicago/Turabian Style

Michail Makridis; Biagio Ciuffo; Georgios Fontaras; Tomer Toledo. 2017. "Free flow acceleration: Humans and car-following models." 2017 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems (MT-ITS) , no. : 262-267.

Journal article
Published: 01 May 2017 in Progress in Energy and Combustion Science
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Official laboratory monitoring data indicate a progressive decline in the average fuel consumption and CO2 emissions of the European passenger car fleet. There is increasing evidence to suggest that officially reported CO2 values do not reflect the actual performance of the vehicles on the road. A reported difference of 30-40% between official values and real-world estimates was found which has been continuously increasing. This paper reviews the influence of different factors which affect fuel consumption and CO2 emissions on the road and in the laboratory. Factors such as driving behavior, vehicle configuration and traffic conditions are reconfirmed as highly influential. Neglected factors (eg side winds, rain, road grade) which may have significant contributions are also identified. Results show that the certification procedure margins can account between 10-20% in the gap between the official values and reality which was estimated to be in the order of 40% (47.5gCO2/km) but could range up to 60% or down to 19% depending on traffic conditions. The introduction of a new test protocol is expected to bridge about half of the present divergence between laboratory and real world. Despite the substantial research found on the topic a lack of common test procedures, analysis tools and methods and most importantly coordinated activity across different countries has been identified. Additional research is needed in order to accurately reproduce real world vehicle operation and propose targeted actions for CO2 reduction. In-use fuel consumption monitoring could be used in order to assess the gap on a continuous basis.JRC.C.4-Sustainable Transpor

ACS Style

Georgios Fontaras; Nikiforos-Georgios Zacharof; Biagio Ciuffo. Fuel consumption and CO 2 emissions from passenger cars in Europe – Laboratory versus real-world emissions. Progress in Energy and Combustion Science 2017, 60, 97 -131.

AMA Style

Georgios Fontaras, Nikiforos-Georgios Zacharof, Biagio Ciuffo. Fuel consumption and CO 2 emissions from passenger cars in Europe – Laboratory versus real-world emissions. Progress in Energy and Combustion Science. 2017; 60 ():97-131.

Chicago/Turabian Style

Georgios Fontaras; Nikiforos-Georgios Zacharof; Biagio Ciuffo. 2017. "Fuel consumption and CO 2 emissions from passenger cars in Europe – Laboratory versus real-world emissions." Progress in Energy and Combustion Science 60, no. : 97-131.

Proceedings article
Published: 28 March 2017 in SAE Technical Paper Series
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ACS Style

Claudio Cubito; Luciano Rolando; Federico Millo; Biagio Ciuffo; Simone Serra; Germana Trentadue; Marcos Garcia Otura; Georgios Fontaras. Energy Management Analysis under Different Operating Modes for a Euro-6 Plug-in Hybrid Passenger Car. SAE Technical Paper Series 2017, 1, 1 .

AMA Style

Claudio Cubito, Luciano Rolando, Federico Millo, Biagio Ciuffo, Simone Serra, Germana Trentadue, Marcos Garcia Otura, Georgios Fontaras. Energy Management Analysis under Different Operating Modes for a Euro-6 Plug-in Hybrid Passenger Car. SAE Technical Paper Series. 2017; 1 ():1.

Chicago/Turabian Style

Claudio Cubito; Luciano Rolando; Federico Millo; Biagio Ciuffo; Simone Serra; Germana Trentadue; Marcos Garcia Otura; Georgios Fontaras. 2017. "Energy Management Analysis under Different Operating Modes for a Euro-6 Plug-in Hybrid Passenger Car." SAE Technical Paper Series 1, no. : 1.