Influence of refurbishment and service life of reinforced concrete buildings structures on the estimation of environmental impact

Abstract

Service life strongly affects results of building LCA and is considered equivalent to that of its structure. Quantitatively obtaining this parameter is a complex task that remains unsolved in the literature. This paper provides a methodology to estimate the service life of a building and quantitative data related to the environmental impact of demolition plus new construction and refurbishment, considering the potential service life and the ability of refurbishment to extend it. This paper focuses on reinforced concrete structures, specifically on beams, as service life of buildings is taken as that of its structure. Firstly, a methodology to estimate the service-life value to conduct the LCA is provided. The applied methodology is based on the definition of different scenarios that include four different approaches to reinforced concrete beam interventions in the long term. The methodology can be extended to a complete building structure. Secondly, LCA of demolition plus new construction and refurbishment in different scenarios are carried out. Finally, the complete methodology is applied to a case study. Concrete structures have a potential service life much longer than the minimum value prescribed in the codes, in this case study, more than five times. Reinforced concrete is subject to degradation and aging with time and several models existing to assess the effects. In addition, a structure can be refurbished, which strongly affects its service life. These different strategies when applied to a case study result in differences of up to 65% in non-renewable primary energy consumption in a 250-year period. Embodied energy and CO2 per year of buildings which are not constant values. The appropriate strategy for a specific case study must be taken into account to select the value of service life in LCA. Reinforced concrete is a highly impacting material, but also a material with a long potential service life. This durability is not considered in the LCA if the service life value is restricted to the minimum one prescribed in the codes. Demolishing a structure (and therefore, a building) that can last 250 years after just 50 or 80 is a highly impacting action. Refurbishment can ensure this durability and even extend it.