The design development phase, both for interior and exterior, is the most important part of the project. The architect will revise the drawings with more specificity and detail than in Schematic Design. Engineering will commence on the structure, plumbing, electrical, heating/ventilation systems, energy analysis and any other project specific systems. At the end of design development, a good deal of product selection and systems design should be progressing. This phase concludes when the interior and exterior design of the building is locked in by the owner and architect. Below is a 3D rendering of a house at completion of design development. The following image is a diagram of the house showing some of the systems and materials in place.