BILL NUMBER: S10200A
SPONSOR: KAVANAGH
 
TITLE OF BILL:
An act to amend the multiple dwelling law, in relation to energy effi-
ciency improvements and certain alterations to multiple dwellings
 
PURPOSE:
This bill would update the window lighting and ventilation requirements
under the Multiple Dwelling Law to accommodate the installation of ener-
gy efficient windows and HVAC equipment to make residential buildings
more comfortable for residents and more energy efficient.
 
SUMMARY OF SPECIFIC PROVISIONS:
Section 1 of the bill amends Section 4 of the Multiple Dwelling Law to
add a definition for "HVAC equipment."
This bill adds three provisions in various sections in the Multiple
Dwelling Law regarding a window's minimum light and ventilation require-
ment as it relates to the replacement of an existing window with a new
window assembly and the installation of HVAC equipment in a window:
1. When an existing window is replaced with a window assembly that has a
lower coefficient of heat transmittance, the new window's allowable
minimum light and ventilation may be reduced by not more than 25% below
the currently required minimum.
2. When HVAC equipment is installed in an existing window, the window's
allowable minimum light and ventilation may be reduced by not more than
25% below the currently required minimum.
3. When an existing window is replaced by a window assembly that has a
lower coefficient of heat transmittance and is installed with 11VAC
equipment, the new window's allowable minimum light and ventilation may
be reduced by not more than 33% below the currently required minimum.
Section 2 of the bill amends Subdivision 5 of Section 30 of the Multiple
Dwelling Law to add these provisions for an existing window in any room,
public hall, or stairs.
Section 3 of the bill amends Paragraph (a) of Subdivision 8 of Section
30 of the Multiple Dwelling Law to add these provisions for windows in
every room, except a water-closet compartment, bathroom, or cooking
space less than eighty square feet in floor surface area.
Section 4 of the bill amends Subdivision 4 of Section 31 of the Multiple
Dwelling Law to add these provisions for dining bays with a floor area
of fifty-five square feet or less.
Section 5 of the bill amends Paragraph c of Subdivision 3 of Section 33
of the Multiple Dwelling Law to add these provisions for windows in
kitchenettes constructed after July 31, 1949.
Section 6 of the bill amends the Opening Paragraph and Paragraph d of
Subdivision 1 of Section 34 of the Multiple Dwelling Law to add these
provisions for windows in multiple dwellings erected after April 18,
1929.
Section 7 of the bill amends Subdivision 1 of Section 36 of the Multiple
Dwelling Law to add the provision on window replacement for public hall
windows in multiple dwellings erected after April 18, 1929.
Section 8 of the bill amends Paragraph h of Subdivision 1 of Section 76
of the Multiple Dwelling Law to provide that when an existing window in
a water-closet compartment, bathroom and general or public toilet room,
and every other room containing one or more water-closets or urinals is
replaced with a window assembly that has a lower coefficient of heat
transmittance, the new window's allowable window area may be reduced to
2 and 1/4 square feet.
Section 9 of the bill amends Paragraph f of Subdivision 2 of Section 107
of the Multiple Dwelling Law to provide that a window in a vestibule or
hall that is readily accessible to the outer air to the extent of at
least 5 and 1/2 square feet of its area, no vent flues need to be
provided within a distance of 40 feet from each side of the window if it
has a glazed area or at least 12 square feet and at least 1/10 of the
superficial floor area of the vestibule or hall. It further provides
that when a window in a vestibule or hall is replaced with a window
assembly that has a lower coefficient of heat transmittance, the new
window may be reduced to the greater of a glazed area of at least 10
square feet or at least 1/12 of the floor area of the vestibule or hall.
Section 10 of the bill amends Subdivision 4 of Section 148 of the Multi-
ple Dwelling Law to add the provision on window replacement for windows
at every stair at every story that is not an interior enclosed stair
separated from and directly accessible to the public hall by a self-
closing fireproof door.
Section 11 of the bill amends Paragraph b of Subdivision 2 of Section
171 of the Multiple Dwelling Law to add all three provisions for windows
in a converted dwelling.
Section 12 of the bill amends Subdivisions 1, 2, and 3 of Section 173 of
the Multiple Dwelling Law to add all three provisions for windows in a
living room and for windows in every living room, bathroom, water-closet
compartment, kitchen and cooking space of a basement permitted to be
occupied for living purposes. Section 12 further sets guidelines for the
height of the top edge of the glazed area and for how much the window
may be opened for every window in basements permitted to be occupied for
living purposes.
Section 13 of the bill amends Subdivision 2 of Section 214 of the Multi-
ple Dwelling Law to add all three provisions for windows in dining bays
of tenement and apartment dwellings containing three or more rooms.
Section 14 of the bill amends the Opening Paragraph and Paragraph 1 of
Subdivision 2 of Section 216 of the Multiple Dwelling Law to add all
three provisions for windows in a basement and cellar of a tenement
dwelling permitted for living purposes. Section 14 also sets guidelines
for the height of the top of each window and for how much the window may
be opened for windows in a basement and tenant dwelling permitted for
living purposes.
Section 15 of the bill amends Paragraph d of Subdivision 3 of Section
216 of the Multiple Dwelling Law to add the provision on window replace-
ment for windows in a basement and cellar of a tenement dwelling permit-
ted for living purposes, and adds that a window's opening may not have
less than nine square feet of clear openings for ventilation.
Section 16 of the bill amends Paragraph b of Subdivision 4 of Section
216 of the Multiple Dwelling Law to add the provision on window replace-
ment for windows in a basement and cellar of a tenement dwelling permit-
ted for living purposes, and adds that a window's opening may not have
less than nine square feet of clear openings for ventilation.
Section 17 of the bill amends Subdivision 5 of Section 217 of the Multi-
ple Dwelling Law to add all three provisions for windows in every public
hall in a tenement erected after April 12, 1901.
Section 18 of the bill amends Paragraph a of Subdivision 11 of Section
248 of the Multiple Dwelling Law to add all three provisions for windows
in rooms for sleeping purposes.
Section 19 of the bill amends Subdivision 7 of Section 277 of the Multi-
ple Dwelling Law to add all three provisions for windows in the living
room of joint living-work quarters for artists and general residential
portions of lofts or manufacturing and commercial buildings altered to
residential use. Section 19 also adds that for kitchens located in
dwelling units having a floor area of 80 square feet or more in joint
living-work quarters for artists and general residential portions of
lofts or manufacturing and commercial buildings altered to residential
use, if a window is replaced with a window assembly that has a lower
coefficient of heat transmittance, the new window's minimum width may be
reduced to no less than 10 inches, the minimum area no less than 2 and
1/4 square feet, or reduced to 1/12 of the floor area of the space,
whichever is greater.
Section 20 of the bill sets forth the effective date.
 
JUSTIFICATION:
The Multiple Dwelling Law (MDL) was enacted in 1929 and governs various
aspects of building standards for multiple dwellings, defined as build-
ings "occupied as the residence or home of three or more families living
independently of each other." The MDL currently applies only in New York
City and the City of Newburgh.
This bill addresses the allowable minimum light and ventilation require-
ments of windows within various types of multiple dwellings, with the
intent to update the MDL's window standards that were not designed for
energy efficiency and meeting climate targets when the law was first
enacted. By reducing a window's minimum glazed area (the surface area
made of transparent materials that lets in light) and ventilation
requirements (the openable area of a window) when a high-efficiency
window or an in-window HVAC unit such as a heat pump is installed, the
MDL amendments proposed under this bill would remove outdated barriers
that keep a building from reaching decarbonization.
One example is New York's Clean Heat For All initiative, a joint-part-
nership established in 2023 between the New York City Housing Authority
(NYCHA), the New York Power Authority (NYPA), and the New York State
Energy Research and Development Authority (NYSERDA) to install in-unit
heat pumps for sustainable heating and cooling, along with new windows
and heatpump-based domestic hot water systems, in NYCHA buildings and
apartments. After a successful 36-unit pilot at NYCHA's Woodside Houses
that saw an 87 percent reduction in energy use from units that received
in-window heat pump units, and with a $38.4 million commitment by New
York City announced in February 2026 that added to Clean Heat For All's
initial $70 million investment by project partners in 2023, NYCHA
expects to upgrade 10,000 of its public housing apartments with heat
pumps and new windows by 2030.
However, under current MDL requirements, for certain existing windows,
installing an in-window heat pump unit, which is larger than an in-win-
dow air conditioner and is not intended to be removable (heat pumps
provide both heating and cooling year-round), and replacing an apart-
ment's existing windows with high-efficiency windows with less glazed
and ventilation areas, would result in violating the MDL's minimum
lighting and ventilation requirements. This limits where NYCHA may
install heat pumps in existing windows and takes away an available tool
to stem energy loss with windows that offer better insulation.
To facilitate NYCHA's efforts to provide reliable heating and cooling to
residents and reduce carbon pollution caused by outdated and inefficient
systems powered by fossil fuels, and to encourage similar efforts in
other multiple dwellings, the MDL must be modernized to accommodate
higher efficiency windows and HVAC equipment.
 
LEGISLATIVE HISTORY:
This is a new bill.
 
FISCAL IMPLICATIONS:
None
 
EFFECTIVE DATE:
This act shall take effect immediately and shall apply to all buildings
in existence on or constructed after such date.

Statutes affected:
S10200: 4 multiple dwelling law, 30 multiple dwelling law, 30(5) multiple dwelling law, 30(8) multiple dwelling law, 31 multiple dwelling law, 31(4) multiple dwelling law, 36 multiple dwelling law, 36(1) multiple dwelling law, 107 multiple dwelling law, 107(2) multiple dwelling law, 148 multiple dwelling law, 148(4) multiple dwelling law, 171 multiple dwelling law, 171(2) multiple dwelling law, 214 multiple dwelling law, 214(2) multiple dwelling law, 216 multiple dwelling law, 216(3) multiple dwelling law, 216(4) multiple dwelling law, 217 multiple dwelling law, 217(5) multiple dwelling law, 248 multiple dwelling law, 248(11) multiple dwelling law
S10200A: 4 multiple dwelling law, 30 multiple dwelling law, 30(5) multiple dwelling law, 30(8) multiple dwelling law, 31 multiple dwelling law, 31(4) multiple dwelling law, 36 multiple dwelling law, 36(1) multiple dwelling law, 107 multiple dwelling law, 107(2) multiple dwelling law, 148 multiple dwelling law, 148(4) multiple dwelling law, 171 multiple dwelling law, 171(2) multiple dwelling law, 214 multiple dwelling law, 214(2) multiple dwelling law, 216 multiple dwelling law, 216(3) multiple dwelling law, 216(4) multiple dwelling law, 217 multiple dwelling law, 217(5) multiple dwelling law, 248 multiple dwelling law, 248(11) multiple dwelling law