Parametric Life-Cycle Costing for Buildings in Early Design Stages

Abstract

Construction companies often try to minimize construction cost while neglecting the total life-cycle costs of a building, yet the cumulated costs for operation, repair and maintenance of a building may even exceed the construction cost over time. Hence, the inclusion of these neglected costs is paramount to an optimized use of scarce financial resources. Inscribed in holistic life-cycle approaches, this thesis operationalizes the concept of life-cycle costing and presents a newly developed parametric life-cycle costing tool that provides valuable means to calculate and evaluate life cycle costs (LCC) of buildings in the Swiss context at an early design stage. The design-oriented tool is based on the visual programming language (VPL) Grasshopper (McNeel & Associates and Rutten 2009) embedded in the Rhino 3D (McNeel & Associates 2018) CAD software.

The idea behind the tool is to facilitate the calculation of total LCC at an early design stage, before the most influential decisions have already been made. As a consequence, cost evaluations in the early design stages offer a high potential to influence future operation costs. A methodology was developed as a basis for the tool development. Based on the international standard ISO 15686-5 (2017), the Swiss standard SIA 480 (2016b) and methodological guidelines authored by the CRB (2012a), costs for construction, repair, replacement and energy supply are taken into account. To calculate the energy costs, a Grasshopper component (Tamvakera 2018) based on the heating demand calculation of SIA 380/1 (2016a) was used. The design-oriented tool therefore creates a novel link between LCC calculation, architectural 3D modelling and quasi steady-state building performance simulation and acts as a prototype for a decision aid and guidance tool. The tool aims to help architects, engineers and real estate developers to make more informed decisions as early as possible in a life-cycle oriented holistic design approach. Its dynamic and parametric nature provides the user with clearly visualized results, fast feedback times and high flexibility in parameter variations related to the choice of building materials, building systems and economic boundary conditions. A case study was conducted to evaluate the capabilities of the parametric life-cycle costing tool. It exemplified the tools possible applications and the importance of changes in the model parameters.