On April 30, 2012, the City Council approved a text amendment to the Zoning Resolution of the City of New York (“Zone Green”) to remove certain impediments to the construction of green buildings and the retrofitting of existing buildings in New York City. Zone Green was proposed by the Department of City Planning (“DCP”) and was based on a set of recommendations issued by the Green Codes Task Force, a group of leading practitioners convened by the Urban Green Council at the request of Mayor Bloomberg and Council Speaker Quinn. City Planning Commission Report and Resolution No. N 120132 ZRY, dated March 28, 2012 (the “CPC Report,” available at http://www.nyc.gov/html/dcp/html/greenbuildings/index.shtml discusses the consideration behind Zone Green. The changes effected by Zone Green are applicable in all zoning districts, except those changes concerning solar energy systems and wind turbines as discussed below.
Zone Green removes impediments in the Zoning Resolution to facilitate the retrofitting of existing buildings with certain green technologies and to ensure that their inclusion in new buildings is not penalized. This summary focuses on the most significant technologies supported by Zone Green, each of which is discussed below: energy-efficient building walls, sun control devices and awnings, solar energy installations, rooftop equipment such as green roofs, rooftop greenhouses, and wind turbines. This summary does not necessarily provide all of the specifications or limitations concerning any particular technology and this discussion is not exhaustive of all of the changes that constitute Zone Green.
Energy-efficient Building Walls
According to the CPC Report, well-insulated exterior building walls are a green building feature that can markedly reduce heating and cooling demands and costs by up to 20 to 50 percent.
Prior to Zone Green, because the Zoning Resolution includes wall thickness in its calculation of floor area and measures lot coverage to the exterior face of exterior walls, the application of external insulation to existing buildings was prohibited if the building was built to its maximum allowable floor area or height, or up to its limits for setbacks, yards and open space. Zone Green allows for the addition of external insulation to buildings existing on or before April 30, 2012 (“Existing Buildings”) by exempting up to eight inches of exterior wall thickness from the floor area calculations and building height limits, and by including exterior wall thickness as a permitted obstruction within yards, setbacks and open areas. Any exempt exterior wall thickness must have a thermal resistance (i.e., the measure of the wall’s ability to retard heat flow) of at least 1.5 per inch.
For buildings constructed after April 30, 2012 (“New Buildings”), Zone Green allows for up to 8 inches of wall thickness to be exempted from the calculation of floor area to encourage high-performance buildings without decreasing the amount of usable space in the building. This exemption applies where above-grade exterior walls exceed the thermal envelope requirement of the New York City Energy Conservation Code by a prescribed percentage. Unlike for Existing Buildings, energy-efficient walls in New Buildings may not project into required yards, setbacks or open areas.
Sun Control Devices and Awnings
Sun control devices and awnings are horizontal or vertical projections that prevent heat gain and provide glare-free natural light, thus reducing cooling and lighting demand and costs. Prior to Zone Green, the Zoning Resolution did not allow for certain of these devices to project over required yards, setbacks and open areas.
Zone Green amended the list of permitted obstructions within required yards, setbacks and open areas specifically to allow sun control devices and awnings above the ground floor to project up to 2 feet 6 inches over these open areas, so long as solid portions of the devices cover no more than 30% of a building’s façade when viewed in elevation.
Solar Energy Installations
The CPC Report states that solar energy is a leading source of renewable energy that has the advantage of incurring relatively low operating costs. Zone Green intends to promote and allow the placement of solar photovoltaic panels and solar thermal systems in places where they have the greatest potential for collecting sunlight: roofs, building setbacks, and building walls that have good sun exposure. Prior to Zone Green, such placement had the potential to violate zoning regulations for maximum building height and required setbacks and yards. Zone Green removes these impediments by allowing solar energy systems as permitted obstructions in the following locations:
Above building setbacks, above the building height limit, and above the roof of Existing Buildings (including those that exceed the height limit), subject to the following limitations:
- On flat roofs, solar panels up to a height of 4 feet are permitted without restriction anywhere below the parapet, regardless of building height. Portions exceeding 4 feet in height may not exceed 25% of the roof area and must be set back at least 6 feet from the street wall. In R1 through R5 districts and in commercial overlays within these districts, the maximum height is 6 feet; in all other districts, the maximum height is 15 feet.
- On sloped roofs, solar energy systems may not exceed 18 inches, as measured perpendicular to the roof surface.
- On top of bulkheads, roof water tanks and other mechanical equipment, provided that the solar energy system does not exceed 6 feet above the surface of the equipment.
- On walls of Existing Buildings, by allowing a projection into a required yard, setback or other required open area, provided that the projection does not exceed 10 inches and does not occupy more than 20% of the surface area of the wall (as viewed in elevation).
- On top of sheds, parking structures and other accessory structures permitted in rear yards, provided that the solar energy system does not exceed 18 inches in height, measured perpendicular to the roof surface or, if located above a permitted commercial or community facility use within a required yard, 4 feet above the structure.
Bulkheads and Other Rooftop Equipment
Rooftops are increasingly being used for purposes ranging from energy conservation (by installation of “green roofs”), storm water management (by installation of “blue roofs,” which are storm water detention systems that control the flow of storm water), and recreational activities (by installation of decks or other surfaces for recreational activities). In addition, rooftops are essential for the placement of certain building systems, such as elevator and stair bulkheads and water tanks, and other mechanical equipment that contributes to energy efficiency, such as boilers or co-generation plants. The existing bulkhead provisions are often too restrictive to accommodate a rooftop configuration that allows for the inclusion of these rooftop systems and/or equipment.
Zone Green addresses these limitations in two basic ways. First, the text amendment includes vegetative roofs, blue roofs and decks as permitted obstructions atop New Buildings with flat roofs, up to a height of 3 feet 6 inches as measured from the maximum building height limit, or atop Existing Buildings (including those that exceed the maximum permitted height) up to a height of 3 feet 6 inches as measured from the roof level. These obstructions are also permitted within a rear yard of a property containing commercial and community facility uses. On sloped roofs (greater than 20 degrees), vegetative roofs are permitted so long as they do not exceed a height of 12 inches, measured perpendicular to the roof. For safety reasons, Zone Green permits guardrails up to a height of 3 feet 6 inches above the accessible roof surface, which may not be more than 30 percent opaque.
Second, Zone Green loosens the bulkhead regulations within certain zoning districts by increasing the volume above the height limit which may be occupied by stair bulkheads, elevator bulkheads, roof water tanks and other accessory mechanical equipment. The new regulation increases the permitted volume, from a surface area limited to 4 times the street wall width, to a surface area that may be 8 times the street wall width. The same has been done in many special districts and in the recently created R5D zoning district. Zone Green extends this formula to medium- and higher-density residential districts, commercial districts and manufacturing districts. Alternatively, a bulkhead may cover 20 percent of the lot coverage of a building, limited to a height of 25 feet where the building height limit is 120 feet or 40 feet where the building height limit exceeds 120. These bulkheads are required to set back more than 20 feet from a wide street line or 25 feet from a narrow street line and all permitted mechanical equipment must be screened on all sides.
According to the CPC Report, one purpose of Zone Green is to encourage the creation of smaller greenhouses associated with schools for educational purposes and larger greenhouses for local food production, especially in industrial areas. Previously, the potential for the construction of rooftop greenhouses was often limited in the event a building was built to its maximum bulk and height.
Zone Green allows, by certification from the Chair of the City Planning Commission, rooftop greenhouses located on top of buildings that do not contain residences or other uses with sleeping accommodations to be exempt from floor area calculations and height limits. Such a greenhouse must only or primarily be used for the cultivation of plants when accessory to a community facility use (such as a school), must have roofs and walls that are at least 70% transparent (except with respect to any permitted storage or office portion not to exceed 20% of the floor space of the greenhouse), may not exceed 25 feet in height and must set back at least 6 feet from all roof edges. In addition, the greenhouse must contain a rainwater collection and reuse system in order to limit water consumption. The Chair certification for a rooftop greenhouse is available in all zoning districts.
Wind energy generation is most effective at high altitudes near the waterfront, where winds are generally steady. Thus, Zone Green allows wind turbines to exceed building height limitations for the first time.
On buildings taller than 100 feet, Zone Green permits wind turbine assemblies to rise up to 55 feet above the rooftop, so long as they are set back at least 10 feet from any zoning lot line.
Additionally, on waterfront blocks in R6 through R10 residential districts and equivalent commercial districts, and in manufacturing districts except M1-1 districts, rooftop turbines are allowed on all buildings at a height of up to half the height of the building or 55 feet, whichever is less. Free-standing turbines are allowed in certain commercial and manufacturing areas on waterfront blocks. All wind installations must comply with specific Department of Buildings requirements.
Zone Green allows greater flexibility for the location of air conditioning condenser units in single- and two-family residences. These central air and ductless mini-split systems are significantly more efficient than air conditioning units installed in windows or through-wall sleeves. Prior to Zone Green, these units were allowed as permitted obstructions in rear yards of single- or two-family residences, but due to noise pollution, they were required to be located at least 8 feet from all lot lines. Zone Green allows air conditioning condenser units to be located in rear and side yards without any setback from lot lines, as they are quieter and smaller in their current iteration, and ductless mini-split units are now a permitted obstruction in a front yard if located within 18 inches of the front building wall and screened from the street by vegetation.
Zone Green also clarifies rules for electric vehicle charging or battery swapping facilities and solar energy generation. It allows electric vehicle charging in all parking facilities and allows charging or battery swapping facilities as Use Group 7D uses, similar to automobile tire or glass establishments, in certain commercial and manufacturing districts. It also specifies that solar energy generation is allowed as accessory to any primary use or as a free-standing commercial Use Group 6D use , permitted in certain commercial and manufacturing districts, similar to electric or gas utility stations, subject to height and setback limits.
Finally, to accommodate high levels of foot traffic generated by schools, Zone Green allows permeable pavement as an alternative to required sidewalk planting strips in lower-density districts.