ARTICLE IN PRESS Energy Policy 37 (2009) 1083–1094 Contents lists available at ScienceDirect Energy Policy journal homepage: www.elsevier.com/locate/enpol How much do incentives affect car purchase? Agent-based microsimulation of consumer choice of new cars—Part II: Forecasting effects of feebates based on energy-efficiency Peter de Haan , Michel G. Mueller, Roland W. Scholz ETH Zurich, Institute for Environmental Decisions, Natural and Social Science Interface, Universitaetstr. 22, CHN J73.2, 8092 Zurich, Switzerland a r t i c l e in fo abstract Article history: Received 7 August 2008 Accepted 3 November 2008 Available online 30 December 2008 In this paper, we simulate the car market in order to forecast the effects of feebate systems based on an energy-labeling scheme using categories A to G. Very fuel-efficient (A) cars receive a cash incentive, highly inefficient (G) cars pay additional fees. Consumers have different price elasticities and behavioral options to react to feebates. They can switch to a smaller sized car, but as energy-efficiency varies widely within size segments, they can also stick to the preferred size class and choose a more efficient (smaller) engine. In addition, previously owned cars influence the next car to be chosen. We use an agent-based microsimulation approach particularly suited to predict environmental and market effects of feebates. Heteorogenous agents choose from a choice set drawn from a detailed fleet of new cars. Incentives of h2000 for A-labeled cars induce an additional rated CO2 emission decrease of new car registrations between 3.4% and 4.3%, with CO2 abatement costs between h6 and h13 per ton, and otherwise little undesired market disturbance. The risk of rebound effects is estimated to be low. After adopting the frequencies of consumer segments to a given country, the model presented is applicable to all European car markets. & 2008 Elsevier Ltd. All rights reserved. Keywords: Energy-efficiency policy Consumer behavior Policy analysis 1. Introduction Exhaust gas after treatment and emission limits in OECD countries have actually reduced the load of most regulated exhaust pollutants (nitrogen oxides, hydrocarbons, etc.) or will do so in the near future (particle emissions from diesel engines). Still increasing however, is fossil energy demand for transportation (IEA, 2006), and resulting CO2 emissions. So after having learnt, within the course of one generation, how to burn fuel in a clean manner, we now face the challenge of using less of it. This challenge is different in nature, as it will call for both, new technical solutions, and changes in human behavior, and might take double the time it took to control regulated pollutants. Among all efforts to reduce our oil dependency, the reduction of fuel use for transportation is unique in many respects. Road transport is the second-largest sector of energy consumption in OECD countries (IEA, 2006), and is the only sector—together with air transport—with still growing energy demand. Energy-efficient cars are available, but market success is often at risk. The reduction potential is large; along with steady technological improvements, behavioral changes (smaller engines and smaller Corresponding author. Tel.: +41 44 632 49 78; fax: +41 44 632 10 29. E-mail address: dehaan@env.ethz.ch (P. de Haan). 0301-4215/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2008.11.003 cars) offer large possible savings. DeCicco and Mark (1998) argue that a large potential for improvement in energy-efficiency persists in increasing consumer adoption of energy-efficient cars. This delineates the mechanisms of consumer behavior in general and of car purchase behavior in particular as decisive factors in reducing energy consumption. However, as average car weight and average power still increase in all car markets, it is evident that a widespread shift of consumers towards energy-efficient cars is still in its beginnings. Feebate systems combine rebates awarded to products with good environmental performance with additional fees for products which have above-average environmental impact. Rebates might also take the form of cash incentives or tax refunds. Fees might be either surplus taxes or a separate registration fee that is billed separately from any other existing type of tax. Feebate systems offer various advantages compared to measures like fuel economy standards or fuel taxes (see Greene et al., 2005; Johnson, 2006, 2007), for example their public acceptance, the possibility to match feebates to specific car types, and hence the potential of feebates to target car purchase decisions. Feebate systems therefore are widely considered (Greene et al., 2005) and have become implemented in various European countries in recent years. While a lack of real-world experience still exists, various studies have modeled effects of feebates (Jansen and Denis, 1999; Langer, 2005). BenDor and Ford (2006) investigate feebate systems and ARTICLE IN PRESS 1084 P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 analyze possible changes in purchasing behavior regarding various fuel types (gasoline, alcohol, electricity and compressed natural gas). Johnson (2007) proposed refunded tax schemes as possible solution to the dilemma between cap-and-trade instruments on the one hand and emission taxes on the other. In the following we argue that under feebates consumers have different options to react in car purchase behavior, but that current practice simulation tools do not fully capture several of these options. Consumers may react by changing to smaller cars, by changing to smaller (i.e., more energy-efficient) engines, by changing fuel type, or by changing powertrain type. If given both options, consumers are more likely to change to smaller engines than to decrease in car size. For example, Peters et al. (2008) report for a mail-back survey of Swiss car buyers (n ¼ 1247), on a 5-rank scale from 1 ¼ ‘‘do not agree at all’’ to 5 ¼ ‘‘do fully agree’’, that 35% of respondents indicated they would change to a smaller car size in exchange for a h1350 feebate (sum of ranks 4 and 5), compared to 40.1% that would change to a smaller engine, mean ranks being significantly different (one-sample two-tailed T test, P ¼ 0.000). This corresponds to a two-stage decision process when purchasing a new car. Hence in feebate simulation models it is crucial to account for all different engine combinations within a given car model and size class. Most car purchase forecast models operate on a more aggregated level; they can, following de Jong et al. (2004), be divided into three categories: Aggregated models (total car stock of a country depending on GDP), cohort models (same target variable as aggregated, but single cohorts can be followed), and disaggregated micro-economic models which operate on the household decision level. The latter can be classified into static (describing household car fleet at a given point of time using discrete choice models) and dynamic approaches (vehicle transaction models, duration models, etc.). However, at present most car purchase models give forecasts only for very few vehicle size classes. For example, Berkovec (1985) has fuel costs as a model parameter to predict car choice, but uses 13 size classes, and fuel cost is assumed being constant per size class. The year 1989 Facts model from the Netherlands Economic Institute, as cited in de Jong et al. (2004), differentiates between three fuel types (gasoline, diesel, LPG) and three weight classes. Golob et al. (1997) present a car choice forecasting model based on a stated preference survey, where fuel cost only differed per car size class and fuel type, but different engine sizes were not investigated. Brownstone et al. (2000) operate with 12 car body sizes and 4 possible fuels, and equally assume that operating fuel costs only differ between car size classes, but not within. The model of Hayashi et al. (2001) uses a car choice model predicting which out of 4 car size classes will be chosen. Mohammadian and Miller (2003) have six car size classes, and treat fuel costs as constant for each of these classes. The vehicle type choice model of Choo and Mokhtarian (2004) distinguishes nine car size classes. A model using a more detailed vehicle fleet is the DVTM (de Jong, 1996), where households choose from 20 out of 1000 makemodel-age class combinations. However, this model does not regard the different engines being available; from an energyoriented point of view, the within-class CO2 variance therefore still remains large. Mannering et al. (2002) distinguish 175 vehicle types, but do not account for differences in energy-efficiency for a given vehicle type. Hocherman et al. (1983) even differentiate between 950 vehicle types, which are characterized by make, size, age, and fuel type, but not by engine size or powertrain. All above mentioned models run at risk not to fully capture the behavioral option of changing to smaller engines while keeping to the car model. This behavioral option, however, is likely to be the most important. In order to capture all behavioral options that car buyers have under feebate systems, it seems beneficial to use a decision model using a two-stage decision model, and using a highly detailed fleet of car models. The paper is structured as follows. In the following section we sketch three different routes towards energy-efficient cars, the EU’s strategy to reduce CO2 emissions from cars, and the resulting need for fiscal policy tools to influence consumer behavior when purchasing new cars. In Section 3 we specify the class of policy tools under investigation, partial and full feebate systems. Section 4 defines four feebate systems and presents results from the microsimulation, i.e. consumer reactions, financial volume, and environmental benefits. We discuss these findings in Section 5. Section 6 assesses the risk for occurrence of rebound effects, and Section 7 concludes. 2. Fiscal measures to reduce CO2 emissions from passenger cars 2.1. Three routes to energy-efficient cars Increasingly stringent tailpipe emission standards in the US, Europe, and Japan, and the need for higher fuel-efficiency, have made the development of engines and powertrains for passenger cars more costly. Accelerated by the globalization of the automotive industry, powertrains and car platforms are therefore often used for various makes and models on all major car markets. In particular, the European car market, historically characterized by strong home brands, and different legislation per country, can today be considered as homogeneous, where all makes and models, and almost all engine configurations, are offered on the various national markets. On the demand side heterogeneous preferences and constraints still lead to remarkable differences between countries regarding the resulting fleet of new registrations. Therefore, all national car markets in Europe can be analyzed using the same simulation model, if data on consumer segments is available. Over the last 30 years, the European car market has seen annual increases in curb weight and rated power of approximately 20 kg and 1.5 kW, respectively (see Fig. 1; note that while relative increase since 1995 for Switzerland is lower than for EU, new car registrations in Switzerland still show highest average weight and rated power of all of Europe). The increase in power partly (but not to full extent) was called for by the surplus in vehicle mass to ensure constant driving characteristics. We therefore use relative power, being the quotient of rated power and curb weight, as yardstick for perceivable engine power. On average for the period 1995–2006, relative power in Europe increased annually by 1.28%, or 0.4 kW/ton. While in principle a strong relationship between car weight and fuel consumption holds, today the variety in engine power (and energy demand) is very large throughout all car size segments. With car model we mean the traditional make-model concept (VW Golf, Chrysler Neon, etc.), whereas a model version is a unique technological choice with respect to body type and powertrain (driveline, engine size, fuel type, and transmission type). An analysis of car models with high sales numbers in Europe (here we use the 15 best-selling passenger car models in Switzerland, which account for over 25% of total sales in 2007), yields an average difference of 94 g CO2/km between the most and the least efficient version of the same passenger car model (Fig. 2). Assuming an average total run distance of 1,60,000 km, this amounts to 15 ton CO2. Therefore, we distinguish three routes to increase energy-efficiency of cars: (a) Switch to lower relative power, i.e. to less powerful engines, for unchanged car size; (b) Switch to smaller sized cars (with proportional decrease in rated power so that relative power remains unchanged); ARTICLE IN PRESS P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 rated power (ACEA) rated power (Switzerland) empty weight (ACEA) empty weight (Switzerland) relative power (ACEA) relative power (Switzerland) 1085 relative change (1995 = 100%) 130% 120% 110% 100% 1995 1996 1997 1998 1999 2000 2001 2002 2004 2004 2005 2006 Fig. 1. Temporal evolution of rated power, curb weight, and relative power for the European car market 1995–2007 (1995 ¼ 100%). Data source: Association of European Car Manufacturers (ACEA). Renault Clio Fiat Punto Peugeot 307 Ford Focus Audi A3 Toyota Yaris Audi A4 Opel Zafira VW Polo VW Touran Opel Astra Skoda Octavia VW Passat BMW 3 Series VW Golf 100 150 200 250 300 CO2 [g/km] Fig. 2. Range of CO2 emissions for all different engine/gearbox combinations on the market for the 15 most-sold car models in Switzerland in 2007. Also shown are 5th, 50th, and 95th percentile of CO2 emissions (126, 187.4, and 273 g CO2/km, respectively) of new car models on sale 2007 in Switzerland. a route b c rated power [kW] car weight [kg] relative power [kW/kg] costs [ ] Fig. 3. Main effects from three different routes to increase fuel efficiency of new car registrations (for further explanation see text). (c) Introduction of new technology to increase energy-efficiency, i.e., hybrid powertrains, lightweight materials, etc. route. Most literature focuses on the supply side (Johnson, 2007, IEA, 2006), as already discussed in Peters et al. (2008). Route (b) achieves its goal at the cost of decreasing car size, which is, for itself, not a target. Route (c) uses more advanced technology to maintain both average car size and average relative power, which is costly. We argue that route (a) is superior in that no decrease in car size is called for and that energy-efficient cars in fact are cheaper. The energy reduction potential of route (a) is substantial, as illustrated by the wide range of CO2 emissions for given car models (Fig. 1), and given that the car market in the last 10 years has shown an increase in average relative power (Fig. 2). We further discuss behavioral implications of route (a) in Section 2.3. 2.2. Current EU strategy As illustrated in Fig. 3, each route finally increases energyefficiency of new car registrations. While (a) and (b) are demandsided, behavioral routes, (c) is the supply-sided technological The strategy of the European Union to reduce CO2 emissions from cars (EU, 1995) consists of three pillars, the first one being ARTICLE IN PRESS 1086 P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 agreements with manufacturers to decrease average CO2 emissions of new car registrations to 140 g/km in 2008 (European car makers) or 2009 (Korean and Japanese car makers). The strategy’s second pillar is consumer information (including booklets reporting fuel consumption of all car models in the market, and compulsory information posters at the point of sale), with the most important part being compulsory energy-labels for all new cars being on display for sale. These labels must contain fuel consumption and CO2 emissions; on a voluntary basis member states may also prescribe additional information where the car in question is rated or ranked in a certain category (see Section 3.1). The strategy’s third pillar consists of fiscal measures that aim at influencing the behavior of consumers when purchasing new cars. The mid-term target of the European Commission is 120 g CO2/km. As the observed progress slowed down from over 1% CO2 reduction annually (from 1995 to 2003) to 0.6% annually (since 2004), this target would not be reached before 2020. Therefore the European Commission wants to introduce additional, fiscal measures (EU, 2007). The present paper investigates one widely debated type of measure that complies with the EU strategy’s third pillar. smaller cars reported higher willingness for behavioral changes. This is investigated further in Peters et al. (2008). 2.5. Effects of incentive schemes In this paper we distinguish and discuss the following impacts of incentive schemes: (a) direct change of demand due to monetary effects (price elasticity), i.e. higher demand for those fuel-efficient cars that are eligible for incentives; and (b) indirect change of demand as incentive schemes also have a normative impact, causing changes in the norms and attitudes of consumers. There is a variety of possible actions to reduce energy demand, conditional to given sets of criteria. Industrialized countries may either reduce domestic energy demand, or pay for reduction efforts in other countries. Energy demand reductions might either be sought within the transportation sector or in other economic sectors. The transportation sector comprises of individual motorized mobility, commercial traffic, public transport, and transport of goods. We defined three routes to reduce energy demand from individual motorized mobility in Section 2.1. Switching to alternative fuels would be another option regarding CO2 emissions, but here we focus on lowering energy demand. We limit ourselves to revenue-neutral feebate systems to decrease domestic energy demand from individual motorized mobility. The income side of such incentive schemes covers the administrative and transfer costs, and cash incentives. Other policy tools (technical standards, higher taxes, voluntary agreements with manufacturers, information campaigns, etc.) are not the scope of the present paper. Feebate systems are a suitable policy tool for route (a)-type reductions in energy demand. Buyers of cars with high energyefficiency would be eligible to a cash incentive. The efficacy of any such feebate system depends on the elasticity, i.e. how consumers change their purchase behavior for a given financial incentive. In addition, long-term impacts on the supply side occur as manufacturers adapt their research and production allocation and ultimately bring new vehicle technology to the market. This aspect is dealt with using macro-economic approaches and in innovation science. Using only the economic concept of price elasticity may be inadequate to predict consumer reactions, since the normative character of punishments and incentives is neglected (Langer, 2005). Our modeling approach accounts for this in part by incorporating psychological effects which may increase the effect of an incentive. We do not model behavioral changes due to changes in norms or attitudes. To the authors’ knowledge there is no literature on quantitative modeling of (b), except from Steg et al. (2001), who use a regression model approach to assess the potential of motivational factors in the reduction of car use. Apart from the monetary effect, feebates based on energylabeling might take effect simply because of the information provided. The availability of thousands of different model versions at present might keep many consumers from informing themselves about recent advances in energy-efficiency. Feebates could draw more attention to the underlying energy-label, and allow consumers to choose cars that better meet their preferences. In addition, growing awareness for energy issues might cause part of new car buyers to change their attitudes towards more efficient vehicles. Most visible at present is the success of hybrid cars, which are being bought by consumers that previously owned larger cars (de Haan et al., 2006, 2007). This is in line with the framework from Coad et al. (submitted) that the information part of feebates, i.e. the energy-label for cars, may be effective in encouraging intrinsically motivated consumers to adopt green cars, while the financial part may be more persuasive for extrinsically motivated consumers. 2.4. Acceptance of feebate sytems 2.6. Possible benefits and drawbacks We conducted a mail-back survey among Swiss households on car purchase behavior, results of which are reported in Peters et al. (2008). A sample of 3920 households was drawn from the phone book, with a response rate of 40.3% (n ¼ 1581). Feebate systems yielded acceptance rates equal to those for pure informational measures (energy-labeling), being the most accepted policy measure tested for. Acceptance on a scale from 1 (‘‘not reasonable at all’’) to 5 (‘‘very reasonable’’) was 3.40 (SD ¼ 1.5), significantly higher than for the purchase of CO2 emission certificates (2.46; SD ¼ 1.4; n ¼ 1424; P ¼ 0.000 for two-sided one-sample Student’s t-test) or higher fuel prices (2.08, SD ¼ 1.36, n ¼ 1445; P ¼ 0.000). Willingness of respondents to change to smaller engines was significantly higher than willingness to change to a smaller car, which is in support for route (a). Larger households, younger people, lower-income households and households preferring Incentive schemes have various impacts on the new car market and, intentionally, on the environmental load of new car registrations. Along the advantages is the internalization of external costs of road transport, which in principle leads to economic gains according to the external cost concept. Other advantages are the promotion of fuel-efficient vehicles (the direct, intended effect) and of environment-friendly individual behavior. The latter may also influence consumer behavior in other energyrelevant consumption field, through increased perception of energy and climate issues (the indirect effect) in general (Wüstenhagen et al., 2007). However, incentive schemes in principle also have disadvantages. There is more governmental regulation with corresponding administrative costs, and every governmental intervention on the market economy runs at risk of lowering the efficiency of the market segment in question. 2.3. Feebate sytems as energy policy tool ARTICLE IN PRESS P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 Moreover, market actors experience adaptation costs, and any regulation is exposed to the risk of not being able to adapt fast enough to technological changes (Nilsson, 2007). Another potential disadvantage is information overload of consumers, if other incentive schemes are active at the same time. 3. Definition of feebates systems 3.1. Energy-labeling of cars Energy-labeling is an information tool, part of the Community Strategy’s second pillar (Section 2.2). The label is similar in appearance to the one for household appliances in Europe. Several European countries use this type of label for passenger cars (United Kingdom, Belgium, Denmark, Netherlands, France, Spain) or consider to do so (Portugal, Germany). It shows seven arrowshaped bars labeled from A (best fuel-efficiency) to G (lowest fuelefficiency), color-coded from green (A) to red (G). Since 2003 this label is also used in Switzerland. Several countries now also the energy-label as basis for incentive schemes (United Kingdom, Netherlands, Portugal) or introduced feebates based on energy demand or CO2 emissions (Belgium, Austria, Denmark, Sweden, Italy, France, Luxembourg, Cyprus). The case study for which we investigate the effects of feebate systems (Section 4) corresponds to a proposed legislation for Switzerland. Due to the market’s homogeneity on the supply side, most aspects of this case study will apply to all national car markets in Europe. 3.2. Relative energy-efficiency vs. absolute energy consumption While there is a certain degree of uniformity on the side of the appearance of the labeling system, every country has its own basis on which classification into categories A to G takes place. Under the ‘‘absolute’’ notion of energy-efficiency, only the absolute level of rated CO2 emissions of the car in question determines its energy-efficiency label (e.g., United Kingdom, Belgium, Denmark, France, each using different bounds between classes). Alternatively, a ‘‘relative’’ energy-efficiency may be computed using the ratio of rated CO2 emissions (or fuel consumption in mass units, as we do not regard alternative low-carbon fuels) to car size. Car size may be operationalized by vehicle floorspace (e.g., Netherlands and Spain) or by curb weight (e.g., Switzerland). This is in line with Johnson (2007), who argues that political acceptability of feebates might be affected by distributional effects, and suggests distributing incentives in proportion to vehicle mass. In the case of Switzerland energy-efficiency, ee, is defined as ee ¼ FCm m0 þ ma where FCm is fuel consumption in mass units (for gasoline we assume an average density of 745 kg m3, for diesel 829 kg m3), m0 ¼ 600 kg is a constant in mass units, m is curb weight, and a ¼ 0.9. The m0 constant is introduced to compensate for the fact that small engines cannot reach the same thermodynamic efficiency as large engines. After choosing a policy base (absolute energy or relative energy-efficiency), also the size of each of the categories of the energy-label has to be defined. In Switzerland, by definition oneseventh of all car model versions being on sale is categorized as A. In total six ee values define boundaries between categories A to G. These boundaries are periodically adjusted in order to account for technological progress, and to ensure that always one-seventh of all model versions has an A label. We used the Swiss energy-label boundaries for the period 2006–2008. 1087 3.3. Other requirements Feebate systems can be designed in a variety of ways, general aims being effectiveness and equity at the lowest possible transaction and implementation costs. Careful consideration should be given to simplicity and fairness in program design, compatibility and coordination with other local vehicle technologyrelated and tax-related programs, the likelihood of ‘‘leakage’’ and, most importantly, the potential for realizing significant emissions benefits. In most cases (DeCicco et al., 1993; BenDor and Ford, 2006), feebate systems are revenue-neutral, i.e., the fees should amount to the sum of implementation costs and total volume of rebates. Apart from only targeting energy(-efficiency), feebates’ policy base can also include other greenhouse gases [GHG] expressed in CO2 equivalents, or emissions of criteria atmospheric pollutants (CAP) like hydrocarbons, oxides of nitrogen, and carbon monoxide (de Haan and Keller, 2000). In the case of the latter, weights have to be given to CAPs and GHGs (this is non-trivial, as there are inherent trade-offs). This makes the calculation slightly more complicated, but also rewards consumers of otherwise ‘‘clean’’ cars. 4. Microsimulation of full and partial feebate systems 4.1. Simulation model The car market microsimulation model described by Mueller and de Haan (2008) is employed. Following a two-stage car purchase decision process, in a first step out of several thousand make-model-engine combinations a choice set is selected, from which in a second step the car to be bought is chosen using a discrete choice model. The latter model is taken from literature and has originally been developed for European Commission’s Directorate General for Environment (COWI, 2002). For a detailed description refer to Mueller and de Haan (2008). We simulate 1 million new car sales, from which aggregated statistics of the fleet of new passenger car registrations are computed. In order to apply the model to a European country other than Switzerland, only the frequencies of consumer segments have to be adapted, followed by a model validation. The model is static in the sense that car choice parameters, demographic data of the population, and the car fleet being on sale do not change. For the simulations in this paper, the commercial consumer group from COWI (2002), that was not regarded in Mueller and de Haan (2008), is included. Retention rates for fuel type, car size class and gear type do not apply to commercial agents, as we do not have market observations from which retention rates for commercial agents could be retrieved. Following the model validation presented in Mueller and de Haan (2008), we calibrated the model. This was done to facilitate communication with stakeholders as the calibrated model closely reproduces 2005 market data that is well known to them. The validated model shows slight underestimations of market shares of inefficient vehicles, and overestimations for efficient vehicles, especially for diesel cars. We interpret this as a persisting bias of consumers against the smallest diesel engines being available. For calibration purposes, weighting coefficients for trunk space were modified. Trunk space as a car utility parameter has become illdefined with new body types like sport-utility vehicles, family vans, and cross-overs. Moreover, trunk space is not recorded in the official type approval data base and has to be parameterized, which is imprecise. Fig. 4 depicts results for the calibrated vs. the original simulation model. Using the statistical performance metrics (for definition see Mueller and de Haan, 2008) normalized ARTICLE IN PRESS 1088 P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 market share 25% 0% CO2 emission categories {<100, <120, <140, <160, <180, <200, <220, <250, <300, ≥300 g/km } 20% market share 0% curb weight cat. {<1000, <1100, <1200, <1300, <1400, <1500, <1600, <1700, <1800, ≥1800 kg } market share 25% 0% rated power categories {<60, <80, <100, <120, <140, <160, <180, ≥180 kW } amount paid out depends on the simulated total sales volume for ‘‘A’’-labeled cars and thus has to be determined based on iterative simulation, ensuring revenue-neutrality. A general purchase tax already is in force, its increase does not lead to additional implementation costs. Administrative costs comprise of transaction costs (estimated at h10 per cash incentive) and fixed costs of 0.8 mio. h annually. Partial feebate system with absolute policy base: same as above, but here cars are categorized based on (absolute) energy consumption. The change from relative to absolute policy base means that some heavier car models leave category A and some smaller car models with only moderate fuel-efficiency are admitted. The changed composition of category A leads to changes in its sales volume. By iteration, revenue-neutrality therefore leads to a slightly different cash incentive amount. Full feebate system with relative policy base: those 15.3% of new registrations having lowest fuel-efficiency pay a fee of h2000 each (the amount of h2000 is fixed here; revenue-neutrality is enforced by slight changes to the size of the A and G categories). This allows for cash incentives to those 14.7% of new registrations having highest fuel-efficiency, and to cover transaction costs of h10 per incentive and h20 per fee (accounting for debit losses). Full feebate system with absolute policy base: same as above, but again cars are categorized based on their (absolute) energy consumption. Again, the changed composition of category A (and G) makes slight modifications to A and G boundaries necessary in order to achieve revenue-neutrality. The model employed is steady-state, i.e. we regard the relative difference between reference run and a policy run. Our main target parameter is the reduction in rated CO2 emission of the fleet of new car registrations, expressed as percentage of the rated CO2 emission for the reference run. To quantify this relative reduction into absolute terms for Switzerland (2005 population: 7.45 mio.), we also report total CO2 reduction, assuming that 2,60,000 new cars are sold per year and that on average each car runs 1,60,000 km. That is, we match an incentive scheme with implementation duration of 12 months to the total life-time effect of the cohort of cars newly registered during those 12 months. Fig. 4. Comparison of validated and calibrated simulation model. For further explanations see text. 4.3. Results for partial feebate systems mean absolute error, NMAE, mean fractional bias, MFB, and correlation coefficient, COR, calibration improves MFB for forecasted CO2 (from 18.06% to 2.46%), curb weight (1.29% to 0.56%), and rated power (1.06% to +1.15%), whereas no significant changes for NMAE and COR occur. 4.2. Definition of reference run and policy runs In the following we compare the reference run to the outcomes under four feebate systems (see Table 1 for details), all having the same ‘‘carrot’’ component (cash incentives), but different ‘‘stick’’ components, and different policy base: Reference run (no incentive scheme): simulation of the Swiss car market for the year 2005. Partial feebate system with relative policy base: purchase tax is increased by 3% of list prices. This on average generates approx. h770 per new registration (annual total for Switzerland being 200 mio; using a CHF/h exchange rate of 1.5). This tax revenue (‘‘stick’’) is refunded by means of cash incentives to A-labeled cars based on their relative energy-efficiency. The exact cash We employ two indicators. Policy efficacy is the relative reduction in rated CO2 emissions, efficiency is administrative costs per abated ton CO2. In addition, market disturbance is assessed by relating efficacy to changes in the curb weight and relative power distributions of new registrations. Table 2 lists selected market statistics and environmental effects. An inherent advantage to the microsimulation approach is that any other statistic could also be computed out of the total of simulated car purchase decisions. The model also simulates effects on emissions of regulated pollutants like nitrogen oxides and particulate matter (Table 2), however their importance is in decline and will show further decline in the future (de Haan, 2009). Fig. 5 shows histograms of market parameters for the reference and both partial feebates runs. Iterative simulation yielded cash incentives of h2550 and h2670 per A-labeled car based on relative energy-efficiency and absolute energy consumption, respectively. The partial feebate systems lead to reduced CO2 emissions of new registrations of 3.1–3.3%. Most notable is a shift towards car models fitted with the smallest available diesel engine. The market share of ‘‘A’’-labeled cars increases, as expected, compensated by only minor market share reductions for categories B to G. The share of diesel cars increases. Due to low implementation ARTICLE IN PRESS P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 1089 Table 1 Definition and aggregated financial figures of the simulated runs. Reference run Partial feebate system Relative base Full feebate system Absolute base Relative base Absolute base Stick component Purchase tax 3% for all categories h 2000 tax surplus for ‘‘A’’ cars (15.3% of sales) Carrot component h2550 incentive for ‘‘A’’ cars h2670 incentive for ‘‘A’’ cars h 2000 incentive for ‘‘A’’ cars (14.7% of sales) Policy base Relative (fuel consump./curb weight) Absolute (fuel consump.) Relative (fuel consump./curb weight) Absolute (fuel consump.) Cash incentive volume (106h/a) Fee volume (106h/a) Purchase tax increase (106h/a) Administration costs (106h/a) 0.0 0.0 0.0 0.0 195.5 0.0 196.8 1.5 190.8 0.0 192.2 1.5 78.0 82.2 0.0 4.2 79.2 83.5 0.0 4.2 Reduction CO2 emissions new reg. (%) CO2 effect (1000 ton) per cohort (total)a Costs per abated ton CO2(h/ton CO2) 0.0 0.0 2.8 221.9 6.9 3.3 260.7 5.9 3.9 304.1 13.7 4.3 337.5 12.5 a Effect over vehicle life (1,60,000 km) of 2,60,000 new cars ( ¼ policy in force during 12 months). Table 2 Environmental and market effects of the simulated runs, relative to reference run. Market statistic Reference run Relative changes induced by feebate systems Partial feebate system Full feebate system Relative base (%) Absolute base (%) Relative base (%) Absolute base (%) Share of diesel passenger cars (%) Microcars market share (%) Subcompact (%) Compact (%) Mid size (%) Full size (%) Luxury (%) Minivan (%) Family van (%) 4WD w/o SUV (%) SUV (%) Cabriolet (%) Sports (%) Curb weight average (kg) Engine capacity average (ccm) Fuel consumption average (L/100 km) Fuel consumption (gasoline only) (L/100 km) Fuel consumption (diesel only) (L/100 km) CO2 emissions average (g/km) NOx emissions average (g/km) Particle emissions average (mg/km) Noise level average (dB(A)) 28.53 3.4 18.0 22.0 21.2 8.5 0.9 8.1 5.3 5.9 3.9 1.0 1.5 1467 1983 7.69 8.10 6.65 188.5 0.104 0.61 72.1 5.2 +1.0 +1.1 +0.6 0.6 0.2 +0.0 +0.0 0.5 0.7 0.4 0.1 0.1 0.8 1.6 3.1 1.1 4.7 2.8 +8.5 +16.5 0.0 2.0 +0.8 +1.5 +0.5 0.8 0.3 0.0 +0.1 0.4 0.7 0.4 0.1 0.1 2.1 3.2 3.3 2.6 4.1 3.3 +2.4 +5.8 0.0 4.7 3.4 18.0 22.0 21.2 8.5 0.9 8.1 5.3 5.9 3.9 1.0 1.5 1.3 3.3 4.1 3.3 3.5 3.9 +8.0 +15.3 0.0 2.0 3.4 18.0 22.0 21.2 8.5 0.9 8.1 5.3 5.9 3.9 1.0 1.5 2.7 4.6 4.2 3.8 4.6 4.3 +1.0 +6.3 0.1 Sales price oh13,500 (%) oh20,000 (%) oh26,500 (%) oh33,500 (%) Xh33,500 (%) 13.3 27.9 24.5 13.3 21.1 +1.3 +0.6 0.3 0.5 1.1 +3.8 +1.2 2.0 1.4 1.6 +0.5 +2.8 0.1 0.8 2.4 +2.3 +3.0 0.5 1.1 3.6 costs, these incentive schemes have abatement costs of h6 per ton CO2. Differences between relative and absolute policy bases are present but not dominant. The absolute basis allows for slightly higher CO2 reductions and hence offers lower CO2 abatement costs. As can be seen from Fig. 5, changes in curb weight distribution are more pronounced for the absolute policy base, while changes in relative power do not show major differences between relative and absolute policy bases. Hence the absolute feebate system reaches its environmental effects at the cost of a higher market disturbance. Other environmental effects (emissions of particles and nitrogen oxides, and noise level) exhibit only very small changes, which are fully due to the higher share of diesel cars. ARTICLE IN PRESS 1090 P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 20% 15% 10% 5% 0% < 1000 < 1100 < 1200 < 1300 < 1400 < 1500 < 1600 < 1700 < 1800 >= 1800 curb weight classes [in kg] 20% 15% 10% 5% 0% < 100 < 120 < 140 < 160 < 180 < 200 CO2 emission [g/km] < 220 < 240 < 300 30% 25% 20% 15% 10% 5% 0% <40 40-50 50-60 60-70 70-80 80-90 90-100 100-110 110-120 >120 relative power classes [kW/t] reference run partial feebates/rel. policy base partial feebates/abs. policy base Fig. 5. Distribution of new car market along curb weight classes (top panel), engine capacity classes (middle), and rated CO2 emission classes (bottom panel), for the reference run (Swiss car market for the year 2005) and two partial feebate system runs. 4.4. Results for full feebate systems Fig. 6 shows histograms of market parameters for the reference run and both full feebates runs. Aggregated market parameters are listed in Table 2 (two right-most columns). In contrast to the partial feebate approach, the full feebate system clearly punishes ‘‘G’’-labeled ‘‘gas-guzzlers’’. This causes a clear drop in market share for the ‘‘G’’ category. Being more selective in its steering effect both when charging fees and when awarding rebates allows for a higher efficacy: average CO2 emissions of new car ARTICLE IN PRESS P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 1091 20% 15% 10% 5% 0% < 1000 < 1100 < 1200 < 1300 < 1400 < 1500 < 1600 < 1700 < 1800 >= 1800 curb weight classes 20% 15% 10% 5% 0% < 100 < 120 < 140 40-50 50-60 < 160 < 180 < 200 < 220 CO2emission [g per km] < 240 < 300 30% 25% 20% 15% 10% 5% 0% < 40 60-70 70-80 80-90 90-100 100-110 110-120 >120 relative power classes [kW/t] reference run full feebates/rel. policy base full feebates/abs. policy base Fig. 6. Same as Fig. 5, but for two full feebate system runs. registrations drop by 3.9% and 4.3% on a relative or on a absolute policy basis, respectively. Note that this higher efficacy is also in part due to the psychological effects incorporated into the simulation model (fees are perceived stronger than rebates, see Mueller and de Haan (2008)). Due to higher implementation costs, however, the abatement cost, at h13.6–12.3 per ton CO2, while still low, is inferior to the one for partial feebate approaches. As in the case of partial feebates, the absolute policy basis appears to be superior in the case of full feebate systems as well. The resulting CO2 reduction effect differs by 10%. Again, the absolute policy base achieves its CO2 reductions at the cost of a higher market disturbance (more pronounced changes in curb weight distribution, see Fig. 6). ARTICLE IN PRESS 1092 P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 5. Discussion To assess the simulated environmental and market effects of feebates, we use policy efficacy (amount of abated CO2) and efficiency (costs per abated ton CO2), and analyze changes in curb weight and relative power distributions to operationalize market disturbance. There are two main findings: We observe high policy efficacy. Cash incentives seem to be able to outweigh utility losses, at least for part of the consumer groups. This is due to the fact that staying with the same car model, while switching to a less powerful engine, causes utility loss only for the acceleration time parameter, but utility gains in sales price, fuel costs, plus the utility of receiving a cash incentive. We observe low market disturbance: In order to become eligible for a cash incentive, consumers are not forced to switch to a smaller car. This can been seen from Figs. 5 and 6, where the relative power histogram reveals more policy-induced changes compare to the curb weight histogram. Fig. 7 illustrates this in more detail for the example of the full feebate run with relative policy base: Gains in market share occur for market segments with lower relative power. If within a car size class enertyefficient engines are available, total market share remains unaffected, but within-class shifts towards lower relative power occur. Decreases in market share do occur for those car size classes for which no engine with A-rated energyefficiency is available (sport/luxury cars, SUV). For the simulation run from our Swiss case study, a high policy efficiency results. As a flat rate purchase tax already exists, partial feebate systems have no administration costs for the ‘‘stick’’ component. A full feebate system means introducing a new tax, which is costly. But full feebate systems have the advantage that both the fee and the rebate have a steering effect, where the ‘‘stick’’ component of partial feebates does not differ between efficient and inefficient cars. Overall, partial feebates are more efficient, but full feebate systems are more effective. magnitude of 20–25% (Spielmann and de Haan, 2008). As a firstorder assumption both inefficient and efficient cars have the same amount of CO2 emissions from these pre- and post-operations life cycle phases. In relation to the total lifecycle CO2 emission of cars, therefore, the reduction effect will be lower than reported here. As GHG emissions have important externalities, the overall economic effect of incentive schemes will be positive. As concluded by Peters et al. (2008), the comparison of efficiency for absolute and relative policy bases calls for detailed microsimulation of car markets, distinguishing different car buyer groups and using a highly detailed fleet of new cars being on offer. The simulation model employed here fulfills these requirements and is hence capable of analyzing differences in changes of consumer behavior under relative and absolute incentive policies. We simulated both partial and full feebate systems on a relative as well as on an absolute policy basis. While having same administrative costs, absolute systems have a 5–10% higher effect in CO2 reduction and hence a 5–10% better policy efficiency. While this effect is clear within the framework of our simulation model, it should be called in mind that acceptance and transparency of policy measures are crucial to their success, as also discussed in Peters et al. (2008). With regard to reliability and validity of our modeling approach, the validation of the model with 2005 Swiss market data on an array of different market statistics (for details, see Mueller and de Haan, 2008) ensures a high level of robustness of the model results. As with all model forecasts, we use past consumer behavior to predict behavorial changes under a future policy instrument, and hence assume that the norms, attitudes, preferences and decision making strategies of new car purchases will not change. As we only investigated incentive schemes that can be implemented immediately, and that are already in force in several countries, and since the financial incentives typically do not exceed 10% of car sales prices, we believe to be well within the area of model applicability. 6. Assessment of potential occurrence of rebound effects The method of agent-based microsimulation that allows us to employ a highly disaggregated fleet of over 2000 car versions on sale is a prerequisite to account for within-model behavioral changes. These changes are the driver of the two above findings. Our simulation results should be regarded as minimum effect; indirect effects as sketched in Section 3 are likely to give rise to even higher effects. On the other hand, the manufacturing and scrapping (Giannouli et al., 2007) of cars also causes significant CO2 emissions within a lifecycle perspective in the order of Car Size Class Sports Car/Convertible Luxury + SUV Fullsize Mid-Size + Van Minivan Compact Subcompact Micro sum sum -0.7% -1.8% -0.2% -0.6% +0.4% +0.7% +1.5% +0.6% Rebound effects are defined as increases in demand induced by efficiency gains (Saunders, 2000). Here we only address potential direct rebound effects (more vehicles being purchased; increase in average car size; more miles being driven) and neglect indirect rebound effects (increased consumption of other goods). Hybrid cars and other technological means to increase fuel-efficiency, corresponding to route (c) from Section 2.1, are characterized by higher investment costs that roughly outweigh the reduced fuel Changes in market share of car size/relative power segments for relative full feebate run +0.2% +2.2% +2.1% <40 40-50 50-60 +0.1% -0.7% -0.8% -0.8% 60-70 70-80 80-90 90-100 relative power categories [kW/t] -1.1% -0.7% 100-110 110-120 -0.6% >120 Fig. 7. Changes in market share of market segments defined by car size class and relative power class. The sum row and sum column give accumulated change in market share for the respective relative power class and car size class. Single, double and triple plus signs indicates market share changes of that specific cell of 0.1–0.2%, 0.2–0.3%, or 40.3%, etc. Reading example: Compared to reference run, full feebate system with relative policy basis leads to 1.8% less luxury vehicles+SUV sales, and to +2.23% market share of model versions with 40–50 kW/ton relative power. Total market share of sub-compact cars with 40–50 kW/ton relative power increased by more than 0.3%. ARTICLE IN PRESS P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 bill (de Haan et al., 2006, 2007), so overall, rebound effects are not likely to occur. However, feebates, that correspond to route (a), induce a switch to more efficient, and less powerful, engines. Consumers will thus have a reduced fuel bill, without needing to invest more. Moreover, while on the one hand an engine with higher energy-efficiency is more expensive to build, on the other hand reduced rated power means lower sales prices in current car markets. In combination, reductions in CO2 of 3.1% and 3.9% (Table 1) are associated with 2.0% and 3.0% reductions (Table 2) in average sales price, respectively. So overall, both purchase price and fuel bill will decrease slightly. If rebound effects would occur, our assumption that total car sales are not affected would not hold. We argue that revenue-neutral feebate systems will not induce significant rebound effects for the following reasons: (1) Incentives of h2000 roughly correspond to the price difference between the cheapest gasoline engine and the most energyefficient diesel engine for car models with high sales volume. So the incentive covers additional investment costs for the most efficient engine. (2) Due to revenue-neutrality, average car price does not change. Of course, as second-order effect, buyers of smaller cars have higher price elasticity (for the 40 consumer groups from the COWI (2002) study used in our simulation model, income group and weighing coefficient for sales price show negative correlation), so an asymmetric market reaction might occur where increased sales of promoted cars are not compensated in full by decreased sales of the cars being punished. However, truly price-sensitive consumers can be expected to buy second-hand cars. (3) If (smaller, low-margin) efficient cars sell more, on the long run car sellers will adjust their profit margins in order to maintain profitability. This would increase prices of A-labeled cars. From a long-term perspective it is desirable, and to be expected, that the car market will learn to earn money with efficient cars rather than powerful cars. Johnson (2007) also argues that one of the main benefits of feebate systems would be the creation of a stable environment towards cars with higher efficiency. (4) To large parts, the demand for car travel in industrialized countries is not cost-constrained, but time-constrained (Schafer and Victor, 2000). Hence savings in time (e.g. through new highways or high-speed trains) potentially have much higher rebound potential (Spielmann et al., 2008), while changes in car price have not. This is supported by total fuel demand in Europe that showed almost no short-term elasticity with regard to pronounced fuel price increases since the year 2005. This is different in North America, where the majority of households has more than one car and can shift to the more efficient vehicle as short-term reaction to fuel price increases. 7. Conclusions In order to reduce the still growing greenhouse gas emissions from individual motorized transport, policy instruments to influence car purchase behavior are among the most discussed. Such policies have been implemented in several countries already. We presented results from an agent-based microsimulation representative for European car markets for partial and full feebate systems. The benefit of employing this model is threefold. First, the method of microsimulation proved to be very successful for communication with stakeholders (Creedy, 2001). Since we use a highly detailed fleet of make-model-engine configurations, there is no need to use disputable car classes or 1093 ‘‘average’’ vehicles. This reduces potential misunderstandings, and has proven to be beneficial for the level of trust that the stakeholders had towards to simulation model. Microsimulation also enables to represent the full complexity (Creedy, 2001) of the policy to be investigated. In stakeholder interaction, this allowed us to implement any thinkable classification criterion (‘‘incentives should only be paid out to diesel cars having particle filter systems’’, ‘‘sport-utility vehicles should be banned from efficiency category A altogether’’, etc.) and to show simulated effects almost immediately. Second, in real-world policy evaluation often the indicators that will be used to compare alternative policies are not yet known at the time of model specification. While the environmental effect in total CO2 reduction and the financial effect in administrative costs were known, the two relative indicators for policy efficiency (taken as costs per reduced ton of CO2) and for market impact (taken as relative power) where put upfront only towards the end of the research project. At any time, microsimulation enables us to compute additional indicators out of the simulated microdata. We illustrated this strength by reporting various indicators on market and environmental impacts. Third, microsimulation allowed for the investigation of detailed effects and therefore to distinguish between similar but yet different tax base definitions. We simulated both feebate approaches based on relative energy-efficiency and based on (absolute) energy consumption. Regarding the simulated results for our Swiss case study, all feebate systems are suited to obtain substantial reductions in energy consumption and CO2 emissions without significant market disturbance, i.e., the statistical distribution of curb weight (being a proxy for car size) remains merely unaffected, whereas relative power shows more pronounced changes (Table 2). This illustrates that car purchasers for the bigger part stay with their preferred car size class, and change their purchase behavior by switching to a more energy-efficient engine (Fig. 7). We expected this based on survey results (Section 2.3). Only with a high level of detail in car model versions, and by using different consumer groups, it is possible to reveal such ‘‘within-car model’’ changes in purchase behavior. A coarser vehicle fleet would have lead to an underestimation of the overall policy effect. On the difference between absolute and relative policy bases, simulated performance is slightly better for feebates based on absolute energy consumption. However, we consider the difference to relative feebates as minor in comparison to the importance of public acceptance. Relative policy bases might reduce distributional effects and increase political acceptability (Johnson, 2007). We therefore conclude that as results from microsimulation do not yield a clear picture on this question, policy makers should be advised to adopt either a relative or a positive policy base, depending on which will ensure higher public acceptance. Feebates for energy-efficient cars have a high public acceptance (Section 2.3), possible reasons being its revenue-neutrality, low CO2 abatement costs, and the fact that CO2 reductions are achieved without pronounced market disturbance. CO2 reductions caused by direct monetary effects (Section 2.4) will decrease as soon as most car purchasers have been subject to the scheme for the first time. CO2 reductions due to indirect effects (changes in consumers’ norms and attitudes) will then gain in importance. Acknowledgements We acknowledge project sponsorship by auto-schweiz (autosuisse), Erdöl-Vereinigung (Union Pétrolière) and the Swiss Federal Office of Energy. The second author is funded by the Swiss National Science Foundation (Grant 105212-105573). ARTICLE IN PRESS 1094 P. de Haan et al. / Energy Policy 37 (2009) 1083–1094 References BenDor, T., Ford, A., 2006. Simulating a combination of feebates and scrappage incentives to reduce automobile emissions. Energy 31, 1197–1214. 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