Adaptive reuse of buildings: Eco-efficiency assessment of retrofit strategies for alternative uses of an historic building

Abstract Adaptive reuse is a process of retrofitting old buildings for new uses. Existing residential buildings in European cities are often being retrofitted to be adapted as office buildings whilst keeping its historical value. The main goal of this article is to perform an eco-efficiency assessment for a historic building to assess alternative retrofit strategies and uses, including investigate how occupancy influences the economic and environmental life-cycle performance of retrofit strategies. A life-cycle model was implemented to a single-family house from the beginning of the 20th century retrofitted to be used as an office building. Nine occupancy scenarios combined with alternative insulation levels were defined. The occupancy scenarios are defined by level of occupancy (office use, and low and high residential occupancy) and set-points (18 °C, 20 °C and 22 °C for heating combined with 23 °C, 25 °C and 27 °C for cooling). The insulation levels comprise alternative roof insulation levels (0, 40, 80 and 120 mm) and exterior-wall inside insulation levels (0, 40 and 80 mm). Eco-efficiency assessment shows that higher comfort conditions result in better eco-efficient results in all types of occupancy. Retrofit strategies with more than 80 mm of roof insulation are not eco-efficient. In summary, different retrofit strategies should be adopted to maximize savings and minimize environmental impacts depending on the type of use and occupancy level. Therefore, it is crucial to take into account both the economic and environmental perspective to support a comprehensive retrofit decision process.