Cost-constrained measures of environmental efficiency: a material balance approach

Joint cost-environmental efficiency analysis based on the material balance principle (MBP) has an important short-coming, in that the measures of allocative efficiency it produces do not fully integrate environmental and economic outcomes. Their limitation lies in their failure to take into account some decision-making units (DMU) use a combination of inputs that is more environmentally-harmful than that of the least-cost unit, or, more rarely, more costly than that of the least-polluting unit. Input substitution can therefore bring both environmental and economic benefits. This paper develops a method for differentiating between environmental allocative efficiency gains that involve an economic trade-off and those that do not. Drawing insight from the literature on multi-criteria analysis, we extend the MBP approach to new measures of cost-constrained environmental efficiency using data envelopment analysis (DEA). The proposed approach is illustrated by an application geared to assessing the efficiency of a sample of greenhouse horticultural production units in Almeria, Spain. The results for this case show that it is possible to increase environmental allocative efficiency by up to 34 % on average without incurring additional costs.