This paper investigates a rather neglected issue regarding the impact of Energy Efficiency Technologies (EETs) on firms' productive performance. Possible influences may arise in the context of internal cost of adjustment, learning by doing effects and the capital vintage. A unique dataset was used which has resulted from a survey carried out among a sample of Greek EET adopters in the manufacturing sector. An econometric framework based on nested non-neutral frontiers, was developed to estimate the influence and the decomposition of EETs on firms' productive performance. The empirical findings reveal that the EETs affect positively the firms' technical efficiency and negatively the deterministic part of the frontier. Significant variations among industries and size groups appear to be present. Some policy implications are derived based on the empirical evidence supporting a mix of energy and technology directions.
