Today, the building industry of Ukraine has gone beyond the limits of sustainable development more than in other parts of the world. This phenomenon has developed from many factors, including Russian aggression, the legacy of the inefficient economy of the USSR, the deterioration of the housing stock, the low incomes of most of the population, and many others. Due to the acute socio-economic crisis, new demands for a return to a steady state can hardly be met. In the opinion of the authors of this article, one of the possible solutions to the problem may be the development of step-by-step strategies for the regeneration of the buildings in the cities. The main problem is determining the optimal pace of social, environmental and economic changes in achieving a sustainable state for the city. Too rapid changes will inevitably lead to an aggravation of the socio-economic crisis. Slow changes will negatively impact the sustainability and ecology of the region. For this reason, in this article, the authors have developed an innovative tool for the evaluation of the optimal value of the speed and acceleration of the modernization of buildings of the city based on the indicator of the ecological path of buildings and the indicator of sustainable availability of life goods for the population that limits the rate of change to a socio-economic acceptable level. This research is a development of the scientific and technical direction «Program complex for modelling a city as a dynamic system».