The LCA study serves as an essential tool for decision-making regarding material selection from economic and environmental perspectives.
Buildings generate environmental impacts throughout their lifecycle stages, from raw material extraction to transportation, production-related environmental aspects, material transport to the site, construction, building use and maintenance, and ultimately, demolition and waste management at the end of their life cycle.
Evaluating a building’s environmental behavior considering its lifecycle identifies construction solutions, minimizing impacts across all stages, starting from the design phase.
This is precisely what the CIRCE technological center has done, commissioned by Zaragoza Vivienda, for the 80 supported housing units located at the intersection of Fray Luis Urbano and María de Aragón streets in the Las Fuentes neighborhood of the Aragonese capital. In this way, CIRCE has conducted an assessment of the building’s environmental behavior using innovative software and tools developed within the framework of the European projects NEED4B and Buildheat.
Specifically, impacts were assessed on a characterization level, considering impact assessment categories of global warming potential, primary energy demand, and water demand. For both the completed construction and the planned project, an analysis was conducted, encompassing earthworks, foundation and horizontal sanitation, structure, roofing, masonry, continuous coverings, paints, carpentry and glass, ventilation, heating and air conditioning, electricity, plumbing, and site and exterior development.
The ground floor of the project includes communal facilities linked to a green area and surface parking. The housing units are distributed from the first to fourth floors.
The foundation is deep, and the structural system consists mainly of reinforced concrete columns and waffle slabs. The building envelope features a ventilated facade finished with cellular polycarbonate, except for the ground floor where brickwork is plastered and finished with exterior resins. The main roof is an inverted system finished with gravel. Lastly, internal compartmentalization is achieved using plastered concrete partition walls and/or dry partitions formed by auxiliary metal structures with incorporated insulation, faced with gypsum board.
Study Results and Conclusions
The results of this initial study reveal that, considering the complete building lifecycle, the two most relevant stages in terms of impact are the production phase and the use phase, which together account for 90% of the total impact in terms of equivalent CO2 emissions. Regarding the production phase, reinforced concrete used in the structure contributes to 16% of total equivalent CO2 emissions, followed by cellular polycarbonate used in the coverings, accounting for 14%.
For the use phase, electrical consumption constitutes 81% of total equivalent CO2 emissions, followed by natural gas (16%) and network water consumption (3%).
When considering the building’s four lifecycle stages (production, construction, use, and end of life), reinforced concrete represents 7.4% of the total emissions, while cellular polycarbonate in the facade accounts for 6.7%. Concerning the latter, changing the material, instead of cellular polycarbonate, would notably affect the production phase. However, altering the facade might impact the building’s energy demand during the use phase. Thus, after conducting the analysis, it’s evident that material selection must consider not only emissions and embodied energy but also necessitates a detailed energy simulation study of the building, accounting for potential modifications.
Furthermore, the analysis revealed that reducing the impacts of the use phase due to electrical grid consumption can be achieved by increasing the contribution of renewable energy (primarily photovoltaics). Finally, to quantify the improvements achievable through different options aimed at reducing the product and use phase impacts of the building, the project recommends evaluating these solutions from a lifecycle perspective, preventing an improvement in the use phase from causing an increase in the product phase impacts and vice versa.
Sustainable construction combines quality and long-term efficiency at an affordable cost, maintaining a commitment to environmental care.
Following the conclusions and recommendations provided by CIRCE in this initial study, Zaragoza Vivienda has decided to make certain modifications to the building’s design, aiming to reduce the environmental impacts stemming from its construction and contribute to the decarbonization strategy of the building sector. Actions have focused on eliminating cellular polycarbonate throughout the project, enhancing the building envelope through increased insulation and improved windows, discontinuing the use of natural gas for heating, and incorporating hybrid solar panels (thermal + photovoltaic).
The lifecycle analysis of the modifications revealed a 16% reduction in equivalent CO2 emissions during the production phase and an 11% reduction during the use phase. This translates to an annual emissions reduction of 24.6 tons of equivalent CO2.
This project, executed by CIRCE, demonstrates that lifecycle analysis is an essential step towards sustainable construction. While conventional construction practices prioritize short-term economic considerations, sustainable construction aligns quality and long-term efficiency at a manageable cost, maintaining a commitment to environmental care.