There is only one file type that uses the .P5D extension:
Planner 5D Project
A P5D file is a project created by Planner 5D, a 2D and 3D home design and interior decor program. It contains a home design project, which includes the layout of the house, construction materials, furniture, and appliances. P5D files may also store objects located around the exterior of the home such as paths, trees, plants, and pools.
Updated: October 14, 2016