Park Slope Townhouse
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Retrofit of a townhouse to Passive House Standard. Park Slope, Brooklyn, NY.
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Architect:
Prospect Architecture
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For up-to-date info see Passive House BKLYN
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Material
Facades 2x3 offstanding stud wall with 3" closed cell SPF. Foam carried back three feet at party walls to mitigate thermal bridging.
Party Walls StoGard for air tightening (both to neighbors and to outdoors - party wall can act as a plenum for air leakage).
Foundation 3" SPF
Roof 12 to 36 inches loose fill cellulose over air-tight drywall ceiling
Windows Optiwin 2-Wood. Custom manufactured for front facade for historical preservation. Fixed upper sash, tilt and turn lower sash.
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Mechanical
Heating and Cooling Daikin Multisplit. 18 MBH FXSQ ducted indoor unit for top three floors, 7 MBH ductless for rental apartment in basement.
Ventilation Zehnder ComfoAir 350. One unit for top three floors, another for basement and cellar.
Hot Water Flat plate solar collectors with natural gas backup. A glycol system is used because, due to historic preservation issues, adequate collector tilt for drainage could not be attained without the collectors being visible from the street.
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My work for this project has, more than any other, proven to be a true collaboration: with Jeremy Shannon of Prospect Architecture, with Robert and his contractors, with Ed Palone the HVAC contractor, with product vendors, and (as for all of my projects) with Marc Rosenbaum. This is especially relevant in a retrofit project, where the complexity of the existing condition unfolds as we go; for instance, rerouting duct work around structure that we didn't know was there, or redesigning insulation details in the absence of structure that we had thought was there.

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2D thermal analysis at party wall
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18 MBH for 2,400 sf
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Solar access survey for DHW