Section 27-2062. Lighting and ventilation in one- and two-family dwellings

a.
    Required windows. Every living room shall have  at  least  one  window
  open  to  a street, public place or an open and unobstructed yard, court
  or other required open space on the same lot as the dwelling.
    b. Size of windows; substitutes for windows. (1) The total area of all
  windows in the room shall be at least one-tenth the floor area  of  such
  room, or twelve square feet, whichever is greater.
    (2)  Skylights,  opening  directly  to  the  outer air, transparent or
  translucent panels or doors, or other natural light  transmitting  media
  may  be  substituted for window openings, subject to the approval of the
  department, if they provide  an  equivalent  amount  of  light  to  that
  transmitted  through  the  window area required in paragraph one of this
  subdivision.
    (3) At least forty-five percent of the required window area,  skylight
  or other openings shall be openable to provide natural ventilation. If a
  mechanical  ventilation  system  provides  forty  cubic  feet of air per
  minute, the openable area may be reduced to twenty-five percent.
    c. Noncomplying rooms. (1) A living  room  in  a  one-  or  two-family
  dwelling  constructed after January first, nineteen hundred thirty-eight
  which meets the minimum room size requirements of article four  of  this
  subchapter  but  does  not comply with subdivision a of this section may
  not be occupied unless it has a single unbroken opening of not less than
  sixty square feet into an immediately adjoining room. The adjoining room
  shall have at least one window opening to the outer air and such  window
  shall be not less than one-tenth of the combined floor area of the room.
    (2)  In  a  one-  or  two-family dwelling constructed prior to January
  first, nineteen hundred  thirty-eight,  an  opening  shall  be  required
  between a room without a window and an immediately adjoining living room
  with  at  least  one  window.  Such opening shall have a minimum size of
  thirty-two and one-half square feet.