Greenwich Passive House Renovation

Photos by Conor Harrigan

Our clients asked us to take an existing 1930’s house on 4.3 acres in Greenwich, CT and transform it into a modern oasis. The goals for this project were not only to modernize a second home and haven for the young New York City family, but to create a gathering and entertainment place for friends, family and kids to have fun. These desires – along with the clients’ sophisticated modern aesthetic - influenced the design significantly and led us, as architects, toward ‘breaking open’ the existing traditional structure to reveal spaces that are open, light filled and playful.

Given that our team - clients, architects, and builders - are all highly invested in sustainable building, our directive was also to turn the old leaky home into an energy efficient, sustainable home. We set our sights on achieving Net Zero and Passive House certifications (Both represent the most stringent energy efficient standards in the world. We are awaiting final certifications.)

With the sustainability goal in mind, we gave ourselves the challenge of keeping as much of the existing house as possible. In the end, the house grew from 8,200 sf existing to 9,000 sf and we:

  • did not add to the footprint

  • rebuilt part of the roof for a third-floor space including media room, bar and pool table

  • fully relocated the kitchen to the center of the house so that it could take full advantage of the private view and swimming pool access

  • created a dining room onto itself that is at once formal and fun enough for everyday use

  • created a spa like primary suite

  • gave every room a light filled, sculptural and spatially flowing atmosphere.

Ultimately by embracing these challenges we transformed a tired duckling into a peaceful, fun and lovely swan while also helping the planet.

SPECIFICATIONS

Energy Modelling led us to double stud walls with 10” thickness filled with mineral wool batts, in addition to 3” of continuous Comfortboard insulation; our typical wall assembly. Wall: R-52

The existing 2x12 roof was insulated with 6.5” of Demilec Heatlock Closed Cell Spray Foam and 4 3/4” of Dense Pack Cellulose. Roof 1: R-55

The new Roof was insulated with 18” of dense pack cellulose. Roof 2: R67

The basement walls are insulated with a combination Demilec Heatlock Closed Cell Spray Foam. 4” of EPS insulation board were placed over the existing slab-on-grade.  Basement: R-25

A continuous air barrier, insulated window bucks and Triple Pane European windows complete the energy efficient envelope. 

BLOWER DOOR TEST   0.6 ACH @ 50pa

The house is 100% electric (except for the gas stove in the kitchen and one gas fireplace.)

Mitsubishi Heat Pumps heating and cooling, Sanden heat pump water heater, Zehnder ERVs and Make up air system comprise the houses mechanical systems.

Solar panels on the roof generate much of the home’s power needs; plans to expand the solar array in the future will help achieve a Net-Zero home.