The article presents the ideas of flexible design in the construction sector. Flexibility in the construction sector was discussed and defined between typical and flexible approaches to design. The idea applied during the economic effectiveness analysis of construction projects was introduced. The issue of flexibility was discussed based on the example of construction of a sports facility - The National Stadium in Warsaw. An effectiveness analysis was applied for variant solutions.

In the early 1990s, the first questions began to arise about the legitimacy of large-scale projects, made on a grand scale for sports events, lasting only a short period. Doubts were not only raised about the organizers’ budgets and the debts often left behind, but also about the impact of these projects on the environment and society. During this time, the word ‘legacy‘ also appeared — in academic discourse, defining the remnants of these competitions. The two most recent editions of the Summer Olympics in Europe were analysed, which did not differ in scale, but due to being played over a longer interval, differed in the awareness of the organizers and the knowledge of how to plan projects more sustainably. The purpose of this work is to demonstrate that the design of Olympic venues in the context of the idea of an Olympic legacy should take into account elements of a strategy for the duration of these venues over time. It is only over a longer period of time that one can assess whether these original assumptions were correct, and the region gained valuable spaces for recreation, or whether they led to the creation of costly unfunctional sports facilities.