Rules for light and air in rooms and buildings

(a) Natural light and ventilation. (1) All guest rooms and habitable rooms within a dwelling unit or congregate residence must be provided with natural light by means of windows or skylights with an area of not less than one-tenth of the floor area of the rooms with a minimum of 10 square feet. Not less than one-half of the required window or skylight area must be openable to provide natural ventilation. (2) All bathrooms, water closet compartments, laundry rooms, and similar rooms must be provided with natural ventilation by means of windows with an openable area not less than one-twentieth of the floor area of the rooms with a minimum of 1.5 square feet. (b) Origin. (1) Required windows must open directly onto the public way or a yard or court located on the same lot as the building. Exception: required windows may open into a roofed porch or lanai where the porch or lanai: (A) Abuts a public way, yard, or court; (B) Has a ceiling height of not less than 7 feet; and (C) Has the longer side at least 50 percent open and unobstructed. The area of fixed openings in open guardrails of minimum height may be credited for this requirement. (2) A required window in a service room may open into a vent shaft that is open and unobstructed to the sky and not less than 4 feet in least dimension. No vent shaft may extend through more than two stories. (3) For the purpose of determining light and ventilation requirements, any room may be considered as a portion of an adjoining room when at least one-half of the area of the common wall is open and unobstructed and provides an opening of not less than one-tenth of the floor area of the interior room or 25 square feet, whichever is greater. (c) Mechanical ventilation. (1) In lieu of required openable windows for natural ventilation, a mechanical ventilation system may be provided for all spaces except bedrooms. (2) Mechanical ventilation systems for bathrooms containing a bathtub or shower or combination thereof, laundry rooms, and similar rooms, must provide not less than five air changes per hour and must be connected directly to the outside. The point of discharge of exhaust air must be at least 3 feet from any opening that allows air entry into occupied portions of the building. (3) Mechanical ventilation systems for all habitable rooms, except bedrooms, and public corridors must be capable of providing not less than two air changes per hour. At least one-fifth of the air supply must be taken from the outside. (4) All bathrooms, lavatories, and toilet compartments that are ventilated by mechanical ventilation must have fixed openings, from adjacent rooms or corridors or from other approved sources, that are sufficient to provide an inflow of air necessary to make exhaust ventilation effective. The exhaust air from bathrooms, lavatories, and toilet compartments may not be recirculated. Exhaust duct systems for toilet compartments and bathrooms must be separate from the exhaust duct systems for other portions of a building. (5) Toilet compartments, bathrooms, and kitchens ventilated in accordance with this subsection may be provided with artificial light. When a water closet in a bathroom or toilet compartment is completely enclosed by partitions, the enclosure must be separately lighted and ventilated. (6) Systems of mechanical ventilation installed to comply with this code must be kept in good working order and in continuous operation at all times during occupancy of the room served by the system. All openings to ventilators must be rat-proofed. (d) Hallways. All public hallways, stairs, and other exitways must be adequately lighted at all times in accordance with the building code. (e) Applicability. Except as provided in this subsection, this section does not apply to the retrofitting and repurposing of nonresidential buildings or structures for multi-family dwelling purposes; provided that: (1) “Multi-family dwelling” has the same meaning as defined in § 21-10.1; (2) The retrofitting or repurposing does not include the rehabilitation of any existing dwelling units other than those allowed by way of this section; (3) Every space intended for human habitation must comply with the natural light or artificial lighting standards and requirements of the International Building Code; (4) Each dwelling unit must be provided with natural ventilation or mechanical ventilation in accordance with the standards and requirements of the International Building Code; (5) In the event of a power outage, for dwelling units exclusively reliant on mechanical ventilation, the fresh air supply system must maintain the delivery of outdoor air to the dwelling units pursuant to the ventilation requirements of the International Building Code. Dwelling units meeting the openable window ventilation requirements of Chapter 16A or the natural ventilation requirements of the International Building Code are not required to be equipped with or utilize a backup emergency power and fresh air supply system; (6) The multi-family dwelling owner or manager, as applicable, shall develop and maintain an evacuation plan; (7) Any purchase or rental agreement for a dwelling unit reliant on mechanical ventilation must include notice that the unit is mechanically ventilated with non-openable windows; and (8) The retrofitting or repurposing is exempt from park dedication or additional off-street parking requirements; provided that: (A) The number of the building’s existing off-street parking spaces satisfies at least 50 percent of the city’s off-street parking requirement; and (B) The building’s floor area, height, and setbacks do not change as a result of adaptive reuse, except for the purpose of providing outdoor amenities for the residential use or activating the street frontage of a ground floor commercial area. ) Editor’s note: In accordance with Ord. 25-3 , the amendments made to § 16A-4.4 do not affect any building permits issued prior to January 1, 2025. All building permit applications received prior to January 1, 2025 and deemed complete for processing by the Department of Planning and Permitting must be processed in accordance with § 16A-4.4 as it read prior to January 1, 2025.