Design development is used to ensure that all the important aspects of a project are clearly defined and developed. This means that elements of the project such as the interior layouts, room size, and materials are defined. This will allow engineers to continue to plan for HVAC, plumbing, and electrical systems properly, allowing for efficient building services engineering.
The deliverable from a design development is a detailed set of drawings, far more detailed than the schematic phase, and includes a specification book. The specification book is a detailed booklet that indicates materials selected, the installation instructions, quality control requirements as well as other technical information.