Every habitable room shall have at least one
window or skylight facing directly to the outdoors. The minimum aggregate
window or skylight area available to unobstructed light shall not
be less than 10% of the floor area of such room or 12 square feet,
whichever is greater. The window or skylight shall either open to
45% of the required area or be supplied with a mechanical ventilation
system of sufficient capacity provided with proper openings for incoming
or outgoing air to assure comparable ventilation. Openings for ventilation
shall include windows, skylights, louvers, monitors or other openings,
provided that all such openings are easily operable by the occupants.
Every bathroom and water closet compartment shall be adequately ventilated with openable area as described in §
159-123, totaling 1 1/2 square feet, or by comparable mechanical ventilation.