Precast Concrete Building Construction and Envelope Thermal Behavior: A Case Study on Portuguese Public Social Housing

A considerable part of Southern European countries building stock was constructed before the implementation of national thermal regulations, and as such, it is currently exposed to challenges such as energy poverty and climate change. Portuguese public social housing presents a significant variety of construction systems and applied typologies. Among them, the "Novobra NK1", a precast concrete construction system that exploits some innovative features in envelope components, has been used in several projects. Considering the importance of retrofitting to improve and adapt the thermal behaviors of buildings to face the aforementioned challenges, this article aims to provide an understanding of the behavior of a NK1 thermal envelope of a dwelling located in Covilha, Portugal, and the impact of some constructive envelope retrofit measures applied. Results show that existing opaque envelope elements and glazed areas present characteristics that are no longer able to provide proper responses to contemporary building constructive requirements. External insulation was identified as a key retrofit measure, window replacement also being an advised solution for rigorous heating seasons. Improvements from the internal side of windows, such as roller shades, may provide few benefits during cooling seasons, and applying solar films is not advised without a proper thermal repercussion analysis.