Against the background that buildings in general and residential buildings in particular impact on the environment, this paper used the life cycle energy and CO2 assessment framework to estimate the primary energy and CO2 emissions content of public housing in Lagos, Nigeria with a view to using the estimate to project for a future housing provision scenario. The importance of life cycle energy assessment (LCEA), a streamlined version of the ISO life cycle assessment (LCA) environmental management tool was highlighted and applied in the study area characterized by poor data conditions for full LCA. Specifically, the operational and embodied energy of the buildings and associated carbon dioxide emissions were addressed. Survey method was used to ascertain household characteristics especially household energy consumption while building materials inventory was obtained from contract documents complemented by observation and interviews. International energy and emissions protocols were used for operational energy and carbon estimation while the ICE database was used for embodied energy and carbon estimation. The study found that at 21,570 MJ/m2, life cycle operational energy intensity dominated embodied intensity which was 7,378 MJ/m2. Also, with life cycle operational and embodied carbon intensities of 1806kg/m2 and 589kg/m2 respectively, the carbon emissions scenario exhibited a similar pattern to the energy scenario. The study also found that while direct fuel combustion dominated operational energy and carbon intensities, initial and recurring materials accounted for the bulk of embodied impact. The above findings imply that in order to ensure sustainability of the housing stock, energy efficiency and carbon mitigation strategies targeted at both the operational and embodied aspects of the buildings should be pursued. In this respect the resort to renewable energy for building operation and low impact building materials for the embodied aspect become very necessary