Daylight as a zoning device for midtown

Since 1960, New York City's Midtown district has experienced an office building boom with the construction of seventy million square feet (650 300 m²) of new office space in one hundred eleven buildings. During this period it became increasingly clear that this new generation of superscale office towers, such as AT & T and IBM, were overpowering their context by dramatically diminishing the daylighting available to the public streets, parks, plazas, and neighboring buildings.The prime cause of this environmental dilemma was the permissive and subjective manner in which the City Planning Commission reviewed Midtown buildings. The waiving of the rigid as-of-right or automatic height and setback regulations for a negotiated review, conceived to encourage good architecture, resulted in daylighting conditions which were measurably worse than those that, in part, led to the call for zoning to protect public access to “light and air” in 1916. The as-of-right zoning regulations which were enacted to guarantee an adequate level of solar access had been superceded by negotiated or discretionary zoning and in the process one of the original goals of zoning was lost.Responding to the defined need for procedural certainty, public accountability, and design and development flexibility, the consultants proposed a performance system of as-of-right zoning based on objective criteria and measurement techniques. The centerpiece of the new building bulk regulations is a modified Waldram Diagram on which the daylighting performance of a building is evaluated against a threshold and standard. The threshold and standard were systematically derived from an analysis of the sixty-year historical expectation for daylight in Midtown. The performance system as adopted by the City is presently being programmed for computer evaluation.