A suggestion may be made regarding some of the principles upon which some buildings are planned Among these are economy of construction, economy of operation, a maximum of rentable space and facilities to attract and retain tenants. In apartments, the location of stairs, elevators, and dumb-waiters must be considered; the rooms of each apartment must be conveniently arranged; there must be sufficient privacy but there should not be too much space devoted to halls. A steam heated apartment will be arranged differently from one in which the tenant heats his own rooms. In the latter the kitchen is often the most important room.

Factory and loft buildings are planned so as to have each floor receive as much light as possible. Plumbing facilities and elevators are placed so that if floors are sub-divided each tenant will be supplied.