Which factor is not relevant in determining the size or type of lightning protection needed for a building?

The choice regarding the building's paint color is not relevant in determining the size or type of lightning protection needed for a building. Lightning protection systems primarily focus on the physical and environmental characteristics of a structure that influence how lightning strikes might occur and how the electrical discharge can be effectively managed.

Factors such as the building's height play a significant role because taller structures are more likely to be struck by lightning due to their increased exposure to atmospheric electrical activity. Similarly, geographical location is essential, as certain areas may have a higher frequency of thunderstorms or lightning strikes, necessitating stronger protection measures. The presence of tall trees nearby can also influence the risk profile; while they may attract lightning strikes themselves, their proximity to the structure can affect how lightning behaves in the surrounding area and consequently influence the design of the protection system.

In contrast, the paint color of the building has no impact on the likelihood of being struck by lightning or the effectiveness of the protection system. Therefore, it is not a consideration in designing a lightning protection strategy, making this answer valid.