Designing usable space will change based on the needs of the building. An office building needs to fit multiple cubicles into a shared area but not pack them so tightly as to decrease productivity. A department store needs space for window displays, as well as space for merchandise, trying on clothes, and purchasing counters. Restaurants need kitchens, and the dining rooms should have enough tables to make a profit but not so many as to create an unpleasant dining experience. The interior designer is in charge of utilizing space in the most effective way.