September 25, 2020

Passive House for a Multi-Family Condominium

We enthusiastically await Charlotte of the Upper West Side’s arrival at 470 Columbus Avenue in Manhattan. The building is poised to become an integral part of a landmarked historic district while looking decidedly toward the future.

The Passive House Institute (PHI) certified design of 470 Columbus Avenue, aka Charlotte of the Upper West Side, aims to set a new standard for energy performance, occupant comfort, and indoor air quality for residential buildings in New York City.  Charlotte’s namesake is a real child; the building’s focus on sustainability, health and wellness, and occupants’ peace of mind is a purposeful endowment toward Charlotte and her generation’s future.  In order to invest in Charlotte’s future, we chose to utilize, and even enhance, PHI design standards in the design of her home. PHI design aims to vastly reduce heating and cooling demand in buildings, resulting in greatly reduced energy use while providing quiet interiors with excellent thermal comfort, regardless of season or exposure. To accomplish those goals, PHI design relies on a nearly airtight building envelope, with robust insulation and triple-glazed windows (and in 470 Columbus’s case, street-facing windows with 4 panes of glass).  Filtered fresh outdoor air will be constantly supplied to every habitable room by a separate ventilation system, distinct from the heating and air conditioning system, substantially raising the indoor air quality inside the residences.  And, importantly in our age of increased invisible air-borne health risks, Charlotte of the Upper West Side will be one of the first residential condominium buildings in New York to introduce Ultraviolet C (UVC) energy throughout its mechanical system to irradiate germs and viruses.


There are many documented health benefits of higher indoor air quality, including a reduced risk of respiratory issues, better sleep, higher productivity, and an overall feeling of wellbeing.  To increase the indoor air quality inside every home at 470 Columbus, filtered fresh air will be supplied by a Swiss engineered Zehnder energy recovery ventilator (ERV) dedicated to each home.  Exhaust air will be continuously extracted and ducted from every bathroom and utility room to balance the continuous fresh air coming in, facilitating a complete exchange of all the air inside each apartment 13 times a day. This exchange rate can be increased 220% under boost mode, controllable by a smartphone app or wall-mounted pads. The street lobby, as well as the amenity area on the lower level, will also be served by dedicated ERVs; like those in the residential units above, the ERVs will be equipped with MERV 13 filters, made of pleated untreated natural material offering 30 times the efficiency of standard fiberglass filters.  MERV 13 filters also remove bacteria, viruses, tobacco smoke, pollen, dust, and dander, while not promoting bacteria, mold, or mildew growth.  Also within every ERV, as well as any supply air component of the HVAC or kitchen makeup air systems, high energy germicidal UVC light systems will be installed, emitting energy at 253.7 nanometer wavelength for optimal germicidal anti-virus irradiation.

Consistent thermal comfort for occupants within each apartment of 470 Columbus will be achieved by the building’s highly insulated exterior walls, its heroically scaled and externally shaded triple glazed thermally broken windows, and a complete ERV ventilation system dedicated to each home treating the incoming fresh air differently according to the season. In winter, the high performance ERV system will remove heat from outgoing stale air and mix it with cold filtered fresh air from the outside; the opposite will occur in the summer to cool the incoming air.  Also, in winter, the ERV’s humidity recovery feature will retain heat and moisture to prevent interiors from feeling dry. In summer, it will extract heat and humidity from incoming fresh air before entering one’s home.  This will help maintain a more stable environment for furniture and art sensitive to changes in humidity and temperature.  The constant indoor temperature induced by the building’s high performance systems and envelope will help minimize the impact of energy cost spikes or power outages, and reduce reliance on sometimes environmentally harmful external energy sources.

Charlotte of the Upper West Side’s energy performance, occupant comfort, and indoor air quality will hopefully set a new benchmark in multi-family residential design, scalable and repeatable anywhere.