The goal of the thesis was to investigate what should be considered in the planning of renovation to ensure the manageability of building pressure conditions. The employer of this thesis was Oulu Building Control, and the goal was to create a guideline about the subject for their website. While the final guide was not completed during the work, the actual content of the information for the guide was compiled.

The information for the thesis was gathered from literature sources and through email interviews. The theoretical basis consists of topics related to building physics phenomena, such as the behavior of air pressure, air impurities, and the behavior of water vapor in the air. In addition, the theoretical basis addresses the air tightness and moisture technical performance of structures, as well as the operation of various ventilation systems. Information from various sources was combined and tied to practical design cases so that those planning renovation construction could easily understand what aspects need to be considered.

As a result of the work, it was noted that building pressure conditions are a highly complex entity influenced by building characteristics, building usage, and surrounding conditions. Pressure differences cannot be eliminated, so in the design, attention should be paid to minimizing their disadvantages and keeping the used solutions as fault tolerating as possible. Continuous monitoring of pressure conditions after renovations is recommended.

For structures, the most crucial factor in pressure condition management is the air tightness of the structures. Poor air tightness allows air leakage through the building, increasing the magnitude of stack effect, wind, and the pressure difference caused by ventilation.

The design and proper adjustment of the ventilation system play a significant role in building pressure conditions. Correct dimensioning of make-up and transfer air routes is essential to ensure that air travels through safe routes. In a supply air ventilation system, it is important to pay attention to both the overall air mass balance and to where the supply air is directed, ensuring it does not lead to room-specific overpressure.