As the environmental impacts of the energy usage of the world today becomes more and more evident, enhancement of energy performance of the already existing building stock becomes more urgent. Buildings belonging to the cultural heritage are often the ones that are most difficult to deal with in this context.

The subject of this thesis is the use of building simulation of historic buildings. The task here is to identify and when necessary develop simulation tools and methods that are suitable for planning of retrofitting strategies in historic buildings, and to identify and analyze what demands such tools and methods would have to fulfill, in what contexts different simulation strategies are suitable, how the demands on the tools might be met and what results and how the results would facilitate the decision making process in the most optimal way. A powerful means to acquire such analyses is the use of whole-building simulation. In the case of historical buildings there are several aspects to take into consideration, determining the choice of simulation tool and method.

This thesis includes

• Investigation of the variability of the demands on simulation tools and methods that the historic buildings pose, and its implication on complexity of the simulation process, and suggestion of a complexity index tool.
• Investigation of the whole-building simulation process and how it complies with the demands identified, and how the exergy concept can be used, exemplified by a case study.
• Identification of a need for a tool and method for a large amount of cases not easily covered by abundantly available tools and methods
• Suggestion of a tool and method to address these cases, and presentation of a case study where the suggested tool and method have been applied, with good agreement between the simulated and measured values.

One important feature of the suggested tool is the Very Small Wall-part Method, that includes the assessment of especially damage prone points into the whole-building simulation model, otherwise unable to accommodate these points. Another is the damage risk assessment feature where a mould risk prediction tool is presented.