Abstract
The building envelope is critical to reducing operational energy in residential buildings. Under moderate climates, as in South-Western Europe (Portugal), thermal operational energy may be substantially reduced with an adequate building envelope selection at the design stage; therefore, it is crucial to assess the trade-offs between operational and embodied impacts. In this work, the environmental influence of building envelope construction with varying thermal performance were assessed for a South-Western European house under two operational patterns using life-cycle assessment (LCA) methodology. Five insulation thickness levels (0–12 cm), four total ventilation levels (0.3–1.2 ac/h), three exterior wall alternatives (double brick, concrete, and wood walls), and six insulation materials were studied. Insulation thickness tipping-points were identified for alternative operational patterns and wall envelopes, considering six environmental impact categories. Life-cycle results show that, under a South-Western European climate, the embodied impacts represent twice the operational impact of a new Portuguese house. Insulation played an important role. However, increasing it beyond the tipping-point is counterproductive. Lowering ventilation levels and adopting wood walls reduced the house life-cycle impacts. Cork was the insulation material with the lowest impact. Thus, under a moderate climate, priority should be given to using LCA to select envelope solutions.
Highlights
Households represent around 27% of the European Union’s (EU) final energy consumption.To address this, EU regulatory efforts have been enacted to promote energy efficiency, and the new EUGreen Deal roadmap aims to encourage that EU building stock become energy and resource efficient
Life-cycle assessment (LCA) has been extensively used to study residential buildings [1,2], building options [3,4], and building construction [5]; most studies have focused on primary energy and/or CO2 emissions, disregarding other environmental impacts
LCA methodology [35] was used to assess the environmental impact of building envelope alternatives for a new South-Western European house located in a mild Mediterranean warm climate in Coimbra, Central Portugal (1460 heating degree days)
Summary
Life-cycle assessment (LCA) has been extensively used to study residential buildings [1,2], building options [3,4], and building construction [5]; most studies have focused on primary energy and/or CO2 emissions, disregarding other environmental impacts. Studies covering cold climate houses in developed countries have concluded that the operational phase has a preponderant weight in the total life-cycle of the building [1,10]. Studies of conventional buildings in different countries (Sweden [11], Kazakhstan [12], Alaska, USA [13], Spain [14], Portugal [15]) have showed that operational energy is dominant, representing 60–90% of the total environmental impacts. A study that provided an LCA benchmark for dwellings in North Italy and Denmark [16] showed that, in North
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