Because the energy costs will increase for housing tenants, and these costs will cover an increasing part of the total income of these tenants in the future, research has been done after the challenge to get the social housing stock sustainable. In this research, it´s about the dwellings in the stock of housing association Trudo. There are several policy frameworks which they have to cope with and various improvements for the construction which can be implemented in social existing houses. For six reference dwellings, several interventions for improving the dwellings’ sustainability have been analyzed. For some dwellings it is possible to achieve an increase in two energy labels, for others there are more options. However, applying such interventions is costly. Besides the technical opportunities, there are solutions on the social field, for example through informing the residents about possibilities to save energy.