Economic vs environmental isocost and isoperformance curves for the seismic and energy improvement of buildings considering Life Cycle Assessment

Abstract

A methodology to quantitatively assess the improvement of seismic and energy performance of masonry buildings through retrofitting interventions is here proposed. The approach is developed at mesoscale level, considering entire façades with openings and taking into account Life Cycle Assessment (LCA). The costs of retrofitting interventions that couple effects of seismic and thermal improvement (called integrated interventions/approaches) are different whether only the construction phase or the entire life cycle of the building is considered. Therefore, it is necessary to estimate at what extent it is correct to neglect LCA in the analysis of integrated approaches. In this paper, the analysis of three masonry façades is performed with and without LCA. Traditional (insulating panels, diatons, ferro-cement) and more innovative interventions (carbon and glass fiber reinforced polymer composites) are considered. For the comparison, isocost and isoperformance curves, which determine both the economic (Euros) and environmental costs (kg CO2eq) for each intervention, are discussed. The comparison shows the necessity of always considering LCA for a reliable assessment: some retrofitting interventions are the most expensive in the construction phase but they result the most convenient in economic terms and in the amount of CO2eq emissions.

Reduction of Housner’s Coefficient of Restitution for Masonry Walls Under One-Sided Rocking

“…We call "experimental ratio of coefficient of restitution" the term: (5) in which is the experimental value of the coefficient of restitution and the analytical value as defined by Housner [12] and recalled in Eq. (2).…”

“…The appropriate types of analysis that can be carried out on masonry buildings under earthquakes depend on the degree of connection between walls and between walls and horizontal diaphragms, including arches, vaults and roofs [1]- [3]. Seismic retrofitting interventions are generally needed to ensure the box-type behavior; nowadays, seismic consolidation techniques are coupled with low-impact solutions also from an environmental point of view [4], [5]. Nevertheless, when the connection is poor, only local analyses are meaningful for a proper seismic vulnerability assessment.…”

Environmental and Economic Impact of Retrofitting Techniques to Prevent Out-of-Plane Failure Modes of Unreinforced Masonry Buildings

“…The thermal transmittance can be computed referring to the relevant international standards, such as EN ISO 6946:2017 [48] for thermal resistance values and EN ISO 10077:2017 [49] for thermal transmittance of glass panels. Indeed, when openings are present, the thermal transmittance of glass panels should be considered, as explained in [13,14]. The thermal transmittance of walls with openings can be synthetically represented by a unique averaged unit value, U, which takes into account all the relevant parameters: the thermal transmittances of the wall, A m •U m , the thermal transmittance of the windows, A w •U w , and the heat flux through the thermal bridges, l•Ψ.…”

“…The methodology was then updated in [13] to consider openings with equivalent transmittance parameters. In a further stage of research, iso-performance curves were proposed as a decisional tool also including life cycle cost analysis (LCCA) and life cycle assessment (LCA) [14]. Analogous design procedures were recently proposed in [15] for reinforced concrete existing buildings.…”

Literature Review of the In-Plane Behavior of Masonry Walls: Theoretical vs. Experimental Results

“…), masonry buildings can collapse or have relevant damage for two main groups of mechanisms: ‘local’ and ‘global’ failure modes. The loss of stability of parts of the structure determines local failure mechanisms [ 1 , 2 , 3 , 4 , 5 ], while all the crises related to the in-plane behavior of masonry walls can be addressed to the global ones. Focusing on the second group, the failure mechanisms are called ‘global’ because they can occur only if the whole structure reacts as a box, according to the so-called ‘box-behavior’.…”