Abstract
The durability of components is characterized by uncertainty, and, consequently, their estimated service life is critical for building project evaluation. Data on the durability of components used as life cycle cost analysis (LCCA) model input are able to influence model construction, model outputs, and residual value calculations. This implies dealing with uncertainty in cost estimates, according to the real estate market dynamics and the economic trends of the construction sector, and in service life estimates during the project time-horizon. This paper acknowledges the methodology presented in previous studies, based on the stochastic global cost calculation. The aim is to propose a methodological step forward by introducing flexibility over time in model input, through a stochastic approach to the Factor Method (FM). This represents an advancement in respect to the FM normed by ISO 15686—part 1:2000. Two different frames, timber and aluminum, as components of a glass façade of an office building project (located in Turin, Northern Italy), are proposed as a case study. The results give full evidence of the capacity of lifespan variables to affect the global cost calculation, overcoming the effects of environmental and financial elements, in contrast with the consolidated literature. The study demonstrates that beta and gamma distributions are preferable when introducing flexibility over time during the building construction processes, confirming the literature on the topic. The methodology adopted is demonstrated to be an effective tool when in presence of alternative investment options, enforcing decision-making in a temporal perspective.
Highlights
Economic and environmental sustainability analyses, in conjoint applications, are recognized to be a fundamental support in decision-making among alternative projects characterized by technical options
ISO 15686:2008 Buildings and constructed assets—Service-life planning, part 5—Life-Cycle Costing [3] indicates life cycle cost analysis (LCCA) as a tool for defining preferable projects according to the economic sustainability viewpoint, through global cost calculation [4]
Where CGEnEC is the life cycle cost, including environmental and economic indicators expressed in stochastic terms; CI is the stochastic investment costs; CEE is the stochastic costs related to embodied energy; CEC is the stochastic costs related to the embodied carbon; Cm is the stochastic maintenance cost, Cr is the stochastic replacement cost; Cdm is the stochastic dismantling cost; Cdp is the stochastic disposal cost; Vr is the residual value; t is the year in which the cost occurred; N is the number of years of the entire period considered for the analysis; and r is the stochastic discount rate
Summary
Economic and environmental sustainability analyses, in conjoint applications, are recognized to be a fundamental support in decision-making among alternative projects characterized by technical options. From the discussion on the results of the mentioned step of research, it emerges that facing a twofold level of uncertainty implies difficulties during the LCCA modeling phase, and during the critical input calculation preliminary to the LCCA application Starting from these premises, in the present research it is assumed that the durability of components and their relative service lives can influence both the model construction and, the model results, and, even more important according to an estimative viewpoint, are able to influence the estimated residual values. The aim of this work is to present a methodological proposal to treat uncertainty related to the variability of the cost items amount, and related to the service lives of the project technical components, or their durability, by introducing flexibility over time.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
