The building sector has a large environmental footprint that contributes to current global GHG emissions. Implementing energy efficiency measures in the building sector will assist in reducing energy consumption and has the potential for substantial CO2 reductions. There is an increased interest for net zero energy buildings to reduce the high energy demands associated with buildings. This paper investigates the techno-economic feasibility of implementing a net zero energy retrofit for a multi-unit residential building (MURB) in Halifax, Canada. An existing and modern 100+ unit MURB was selected and modeled in its current state using a building energy performance software. Iterations of energy efficiency modifications were implemented until the total annual energy consumption was reduced to a level that would allow for the building to achieve net zero energy status by incorporating renewable energy capacity. This paper presents the methodology, the retrofit technologies and renewable energy installation used, and their economic implications. The results show the economic feasibility constraints for a MURB retrofit to achieve net zero status in the cold climate of Halifax.