It's good easy to learn to use for MEP Drawings Brics CAD can use Cad & BIM extension file DWG # Philemon _Dubai
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
iCADMac - User friendly 2D/3D CAD software for MAC OS X, which reads and writes DWG format drawing files.
SketchUp - 3D for Everyone
AutoCAD LT - AutoCAD LT is a drafting tool to create 2D drawings.
FreeCAD - An open-source parametric 3D modeler
progeCAD - progeCAD is DWG/DXF-native CAD software, built for professional drafting.