An interior layout is important to space plan as this is the key which impacts on how functional the workspace will be.
Consideration needs to be given to how the workspace or room will be used and what will the look and feel ultimately be. Look at ergonomics, traffic flow efficiency, privacy, colour and overall room lighting as all these will greatly help with overall functionality and can make everyone feel better.
Space planning is especially important in construction and refurbishment as mistakes can be costly. It is important that your requirements are well thought out so as to create a layout that is practical and actually works, this will also ensure that there is no wastage.