 Tenants and rental income were essential to the financial success of any skyscraper, as even the largest skyscrapers and those founded by prominent companies rented out much of their office space.Owners could charge significantly more for office space close to the main windows, making it most efficient to build skyscrapers with as much premium office space as possible, even if this cost slightly more to construct in the first instance.As a result, a standard pattern for office units in both New York and Chicago emerged, with either a single rectangular office adjoining an exterior wall, or a "T" shaped design, with a reception room giving way to two windowed offices, separated by glass partitions.