Damage risks in historic buildings are often connected to moisture level, in turn related to temperature. Hence, when damage risk is being assessed, the risk at the points in the geometry of the building where the heat flow is the largest, for instance by the thermal bridges, is of crucial interest. In practice, such assessments may often be based on simulated average conditions of the room air, instead being made for the risk-prone points where the damages are most likely to occur. The reason is that the whole-building simulation tools are generally one-dimensional in their calculations, and unable to deal with the multidimensional heat flows at the thermal bridges. Hence the actual damage risk remains unknown, and may be under-estimated to an extent that is impossible to evaluate, without further investigations. Subsequent investigations can be performed for assumed risk-prone points, using two- or three-dimensional simulation tools, but in order to know what points that needs to be scrutinized it would be of value to get a first risk assessment directly in the whole building simulation process. In this article a method, based on the use of equivalent wall-parts, mimicking the performance of the most extreme points of the thermal bridges, is presented. It is displayed how the use of the wall-parts may provide an overview of the risk levels already in the whole-building simulation.