Renovation at district scale is a key strategy to reduce CO2 emissions and energy consumptions by optimising the implementation of renewable energy sources and taking advantage of economies of scale. In this context, this paper focuses on assessing the positive impacts and difficulties after the energy rehabilitation of thermal envelopes in two buildings that belong to two different District Heating systems. The methodology is based on the comparative analysis of indoor temperatures data and energy consumption data of 17 monitored dwellings. The results showed a significant association between the improvement of envelopes and the increase of indoor temperatures in winter (ß=0,644). Due to some technical and social barriers, the heating system was not regulated after the rehabilitation, so energy consumption was unnecessarily high, there were situations of indoor overheating in winter (maximum average indoor temperatures between 24-26°C) and these issues produced dissatisfaction on neighbours. In order to avoid these negative consequences, some recommendations are provided, such as informing neighbours about expectations in each step of the long rehabilitation process, reconsidering payments to promote the envelope rehabilitation but maintaining a fixed cost to protect vulnerable groups, and promoting post-occupational studies that contribute to the viability and up-date of this kind of District Heating systems.