The rebound effect of design alternatives

The graphical presentation of the EVR of a product reveals the fundamental differences between two (or more) alternative designs. Two examples from the automotive industry are shown here to explain the EVR model in further detail, and to explain the “rebound effect” which stems from consumer behaviour.

The first design alternative: reducing fuel consumption by reducing the weight of a car.
One of the strategies of reducing the environmental impact of cars throughout the lifecycle is the reduction of fuel consumption. This can be achieved by making cars lighter.

Fig. 4.3a shows the result of calculations on costs (market value) as well as ecocosts for middle class German cars (Audi) and for European fuel prices 1999. The left hand side of the two lines relate with the production (the end-of-life phase included) of a specific

part of the coach-work of the car. The right hand side of the two lines depicts the effect of the fuel consumption related to that specific part of the coach-work (0.305 litre fuel per 100 km and 100 kg; reduction of weight approx 16 kg).
At a total lifetime of 250,000 km, the solution with SMC (a polymer) is break even with steel from the economic point of view (economic savings on the fuel equal the extra costs of the coach-work),. However, the solution with the polymer coachwork is much better from the environmental point of view.
Note: It is good to mention here that the change in cost structure (from energy costs towards product costs) has a serious impact on the marketing of the product. When the aforementioned example of coach-work is applied to the total car (a hypothetical case), the price of the car will go up with nearly a factor two-and-half, which may only be marketed via total lease concepts (for the total lifetime of the car).