CAD, or computer-aided design and drafting (CADD), is the use of computer technology for design and design documentation. CAD software replaces manual drafting with an automated process. CAD programs have different features depending on whether your design process involves 2D vector-based graphics or 3D modeling of solid surfaces. Most 3D CAD programs let you apply multiple light sources, rotate objects in three dimensions, and render designs from any angle.
This is what might be considered as CAD drafting in its basic form but none the less, accuracy is a very important part of the process. Taking existing record drawings and using traditional and conventional drafting methods, the existing drawings are completely redrawn in CAD. This method should not be confused with raster to vector scanning, both methods have there uses. These drawings are scaled from the original documents and the results are a cleaner, more accurate and usable electronic CAD file.
As 3D visualisation is fast becoming the norm for developers and architects, its imperative that building services engineers and contractors are also able to demonstrate their expertise through 3D models of the services they are designing or installing. Using 3D services models to develop coordination drawings, ensures that the design can be visualised and developed to assist and improve the installation process. Using these models can also provide a great opportunity to visualise and consider future maintenance and plant replacement scenarios where space is limited.