113 Architectural questions - In which planning phase are the costs determined?
In which planning phase are the costs determined?
The main cost-determining decisions are made at the beginning of the planning phase - sometimes even before.
The search for a project site can have a significant impact on project costs due to framework conditions such as the building ground, groundwater, emissions, etc.
Even during the planning stage, the earlier in the process the more far-reaching the decisions. It is also possible to control the costs at the beginning, but towards the end of the planning and especially towards the end of the realisation, only ever smaller ranges can be made through planning decisions.
For example, the shape of the structure and the structural framework have a very high influence on the costs, as does the foundation concept. Once these planning decisions have been made, it is very difficult to deviate from them at a later stage and this would result in extensive re-planning.
The proportion of windows, the decision on the type of façade and the decision on the energy concept must also be made relatively early on and, if possible, not changed.
In addition, the operating and life cycle costs are also determined at a relatively early stage in the planning process.
This principle can be figuratively compared to a "cost funnel" or a "cost trumpet". The wide range of a cost estimate also reflects the extent to which costs can be influenced by planning decisions. In the cost calculation, the uncertainty is low - not only because the planning has far fewer quantitative unknowns at this stage, but especially because the qualitatively cost-relevant decisions have been made.
In any case, the better the planning, the fewer cost-relevant surprises there will be during realisation!
