Narrowband IoT (NB-IoT) is a Low Power Wide Area Network (LPWAN) radio technology standard that uses a subset of the Long-Term Evolution (LTE) specification issued by the 3rd Generation Partnership Project (3GPP). NB-IoT focuses specifically on extended coverage, long battery life and support for a large number of connected devices. Since the ns-3 simulator is already a popular platform for LTE research purposes, it can be adapted for NB-IoT simulations. In this paper, we present the ns-3 design and implementation details of power saving schemes for NB-IoT to evaluate the device’s energy consumption and latency. The important features of power saving schemes include Power Saving Mode (PSM), extended Discontinuous Reception (eDRX) and Idle mode paging. We have validated our implementation by running and analyzing various experiments. The implemented code is available as open source.