Holistic model for the assessment of restoration projects of heritage housing. Case studies in Lisbon

Abstract

Abstract In urban centres across Europe, a large number of old dwellings, some of which are heritage buildings, fail to meet the current habitability standards. In order to achieve sustainable urban restoration, it is necessary to act from social, economic, and environmental standpoints, and also to promote socio-cultural sustainability and to prevent depopulation. The environmental assessment is a particularly complicated task in restoration projects of heritage buildings. Economic control, however, is often carried out, especially in publicly funded projects. The model proposed simultaneously enables the economic-environmental assessment of rehabilitation actions carried out on heritage housing. Three case studies of heritage housing in Lisbon (Portugal) are evaluated. The tool proposed is based on standardisation criteria and on conversion factors of work actions that transform them into cost and environmental impact. New work units related to seismic reinforcement are included, due to Lisbon’s history of earthquakes. The model also compares restoration costs to those of demolition and new construction; the cost is only 5–15% lower, but the environmental impact is 70 % lower than in a new construction. Furthermore, a reduction of over 50 % in annual CO2 emissions and 80 % in energy consumption for heating and cooling are also verified. The model evaluates the rehabilitation of heritage buildings from a holistic perspective in order to assist in the future planning and definition of urban political strategies.