Non-urbanized areas (NUAs) play an important role in reducing the effects of climate change by providing both carbon storage and sequestration. Urban areas are responsible for the emission of 60% of global greenhouse gas, 50% of which are produced by buildings. During the past decades, increasing urban growth and sprawl processes produced several urban layouts characterized by different morphological features and a common lack of sustainable energy and environmental solutions. Investigating the relationship between urban morphology, energy demand and carbon emission/sequestration represents a relevant topic for urban planning practices implemented to face urban climate change effects. This study proposes a method for a transformability assessment aimed at investigating the transformation suitability of different urban morphology types. The case study is the metropolitan area of Catania (Italy), characterized by an impressive urban growth since the 1960s. The proposed method identification of limits and options for increasing sustainability of urban areas considering the contribution of both NUAs and built-up areas. This approach allows to identify appropriate planning tools for new layouts of urban fabrics while increasing the objectivity of the decision process. In the framework of climate change mitigation and adaptation, the outcomes of this research may lead to innovative urban planning practices.