It is known that distributed antenna systems (DAS) using radio-over-fiber (RoF) links are able to increase coverage and to improve energy efficiency compared to traditional wireless access networks. In this paper, we focus on the energy efficiency of 802.11n RoF DAS architectures and we provide a methodology based on ns-3 to evaluate and optimize energy consumption in those environments. Our results confirm that there exists an optimal number of distributed antennas for a given scenario. Furthermore, we show that aggregation mechanisms included in IEEE 802.11n enable to further improve the energy efficiency in RoF DAS. Finally, we demonstrate that media access control protocol data unit aggregation techniques outperform media access control service data unit aggregation schemes in providing higher end-to-end throughput and a better energy efficiency in IEEE 802.11n RoF DAS.