Two factors that cause hardwood floors to fade are sun exposure and the finish that is applied to the floor.
Installing your hardwood floors in an area that has direct sunlight can cause your hardwood floor to fade overtime. This is very similar to how skin reacts when exposed to sunlight. You could prevent the floors from fading by moving furniture periodically to limit that exposure.
The second factor is the finish applied to the floor. Oil-modified finishes will give the floor a slightly yellow appearance over time. In contrast, water-based finishes generally will remain clear over time.