The client’s intended use for the space, “efficiency,” is a while common approach to any building, is a terrible idea for how to layout the space for its intended users. An office building should be spacious and allow for views and light for natural light to reach the users. My approach to solving this problem would be express my concern for the “efficient” approach and to design for opportunities that are beneficial to the users, such as ways to bring in more natural light.
A bit of information that I would ask of the client is the amount of employees do they intend to have working. As well if they would want any additional programming other than work space.
These issues need to be discussed as soon as possible. So they should be discussed during the programming stage of the process. Having these problems discussed with the client early on will give more time to plan for this effectively and efficiently.