The increasing number of elderly people (over 65 years of age), long-term home care policies and the generally higher energy demand of houses inhabited by elderly people will pose an energy challenge for the built environment. The paper analyses the benefits of poly-generation technologies, focusing on the case of hard to heat homes in Northern Ireland. The energy consumption of a test house that is representative of 28% of Northern Ireland housing stock and of a house with elderly inhabitants has been monitored without any intervention. An optimization procedure has been developed to identify the optimal mix of poly-generation technologies. The technologies considered are micro-combined heat and power, heat pump and photovoltaic systems with possible integration of thermal energy storage systems. Six scenarios based on different energy tariffs and technology incentives have been presented. In the best case scenario, the combination of photovoltaic, heat pump and thermal energy storage provides 26% reduction in carbon dioxide emissions and 80% savings in the energy bill compared to standard energy generation. The investment required would be in the order of 11,000 pound. In Northern Ireland, 307,000 households (79.1% more than in 2012) will have elderly inhabitants by 2037. The adoption of poly-generation technologies in the older housing stock could lead to 8% reduction of carbon dioxide emissions of the entire residential sector, with 150 GWh increase in the electricity generation from renewable energy without affecting the electricity distribution network.