Environmental feasibility of heritage buildings rehabilitation

Rehabilitating a building is a unique opportunity to reach higher levels of environmental performance and reduce energy consumption and CO2 emissions required for its operation. In contrast to the activities of demolition and construction of new buildings, rehabilitation brings environmental and economic advantages. When applied to buildings with cultural significance, architectural rehabilitation also promotes an important social capital - the built heritage. However, rehabilitation activities have an environmental load in themselves. Even the interventions aiming to improve the performance of existing buildings can have a negative effect on the environment. The prospect of environmental indicators to evaluate the feasibility of architectural rehabilitation has been the focus of interest in this research. An extensive literature review on the subject addressed studies from the 1970s to the most recent works, finding that the concept of avoided environmental impact is a relevant approach. In this concept, the feasibility of rehabilitation can be determined from the comparison between the environmental impacts involved in the rehabilitation and use of an existing building and those arising from the demolition of a building followed by the construction and use of a new equivalent building. As for establishing indicators based on the concept of avoided impact, studies of excellence rely on life cycle assessments. The life cycle assessment is a unique method to assess the environmental performance of buildings and in decision-making in building projects. Rehabilitated buildings have their usage value restored and their obsolescence reversed. The use value of a building can be determined in terms of environmental, social and economic indicators. To be effective in restoring the use value, the building rehabilitation should be feasible in those three aspects. The ability to demonstrate the environmental benefits in conserving buildings of cultural value brings new alternatives to preserve that heritage.