Mechanical, electrical, and plumbing (MEP) refers to these aspects of building design and construction. In commercial buildings these aspects are often designed by an engineering firm specializing in MEP. MEP design is important for design decision-making, accurate documentation, performance and cost-estimation, construction planning, managing and operating the resulting facility.
As with other aspect of buildings, MEP drafting, design and documentation were traditionally done manually. Computer-aided design had some advantages over this, in some instances including 3D modeling. Building information modeling provides holistic design and parametric change management of the MEP design.