Establishing a new building is generally believed to be quite difficult. Therefore, exceptionally in case of the most demanding buildings there are many people who are responsible for the organizing of the whole process. For example many work that has to be put into this process has to be divided in time and among various employees.
When spring has already arrived, we are ready to perform far more actions then in the time of colder months. We are doing any exercising on the open air, having a picnic on the grass, traveling with a bike. Beside, if we were earlier planning to perform some renovation, this is the best term.