The Course of Cost Variability During the Execution of Sustainable Construction Projects

The article presents the results of research on the course of variability of planned and actual cost during the implementation of sustainable construction projects. The correlation of cost-time parameters in implementation in a group of 41 investment tasks, classified into five typologically homogeneous construction sectors in Poland, completed in the years 2006 – 2025, was examined. All of these enterprises have been designed and carried out within sustainable requirements and all fulfilled either platinum or gold LEED certification. The logistic centres have been executed in line with BREEAM certification. The course of cost volatility and the functions of the cost trend during the implementation of sustainable investment tasks were determined. Proven managerial tools were used, well described scientifically – the S-curve and the EVM method. The result of the research achievement is to confirm the correctness of the main thesis of the research: cost and time of implementation are not completely interdependent parameters and show great variability during the implementation of typologically diverse, although uniformly balanced construction projects. Finally – as regard sustainability – there is no correlation between sustainable design with execution and cost course of construction projects. Deep analysis of construction costs variability of sustainable diverse enterprises led to the main conclusion: design and construction of sustainable projects in accordance to LEED or BREEAM certification do not guarantee execution projects in line with their planned cost, no matter what sector the project belongs to.