Indoor pressure is generally similar to outdoor pressure, but there can be slight differences due to factors like ventilation and air-tightness of the building. In an air-tight room, the pressure can vary significantly from the outside, especially if air is removed or added. If indoor pressure is lower than outdoor pressure, it can lead to structural issues or air movement into the building. Conversely, higher indoor pressure can cause air to escape, affecting energy efficiency. Understanding these dynamics is crucial for building design and environmental control.