Following the Paris Agreement, several governmental bodies in the United Arab Emirates (UAE) started working on further initiatives to improve the energy efficiency of buildings. Some of these hope to target net-zero carbon for new and existing buildings. As in most countries, the stock of existing buildings represents the bigger challenge for this target. In particular, existing affordable housing is the most challenging segment of the building stock. The limited access to expertise and financial resources makes it more difficult for owners of these buildings to retrofit them. Therefore, there need to be appropriate guidelines on how to achieve net-zero carbon in such building typology. This paper identifies both the technical and the financial challenges when trying to develop such guidelines within the context of the UAE. It also discusses the possible solutions that can be used to overcome some of these challenges. The technical challenges include the variation in construction systems, and the quality of construction for these buildings. It also includes energy modelling challenges such as selecting relevant weather data, and defining the patterns of using electricity for the different functions. The financial challenges include the subsidized price for electricity, the cost estimation for various energy conservation methods, and the payback for installing local renewable energy sources. Finally, the paper suggests a path for research activities to address these challenges and to develop the guidelines.