

ALONE HOUSE
Single Family Residential
New Construction
2,450 SF
Philadelphia, PA: Northern Liberties
This small citadel developed through the owner’s desire for a house-as-retreat. For the better part of a decade, the occupants of this single-family house experienced rapid change in their Philadelphia neighborhood: gritty artist studios and open green lots were infilled with mass residential development and large-scale construction. The project fortifies the residents from the changing environment.
As opposed to traditional rowhome construction where neighbors share a “party” wall, the building pulls away from its masonry neighbors to produce two buffer yards. This eliminates noise infiltration from adjacent properties while offering a continuous belt of outdoor living space. In comparison to the nearly windowless street-facing walls, the house becomes permeable at the rear where maximum solar exposure occurs. Double-stud exterior walls create fourteen inches of sound attenuation between street and interior. Thicker assemblies and air-tight construction provide for smaller mechanical systems, minimal energy bills and indoor air quality that is otherwise rare in an urban setting.

PROJECT STATS
Passive House
Building Geometry
Surface Area to Volume: 0.21 sf/cf
Heat Loss Form Factor: 3.13
Building Metrics
Predicted Energy Use Intensity (pEUI): 4.39 kBtu/sf/yr
Actual Energy Use Intensity (EUI): 1.4 kBtu/sf/yr
Home Energy Rating Score (HERS Index): 14
Airtightness (measured): 0.62 ACH50
Building Envelope
Slab On Grade: R-22.5
Below / Above Grade Walls: R-28 / R-42
Roof: R-72
Windows: Average SHGC .61, average U-Value .21
Skylights: SHGC .49, U-Value .15
Building Systems
Power / Fuel Source(s): All electric
Renewable Energy: Rooftop solar PV (3.78 kW system size; 4,373 kWh est. annual solar production)
Heating & Cooling: Ductless mini-split heat pump
Energy recovery ventilation
Domestic Hot Water: Heat pump water heater
Appliances: Energy-Star
LED lighting
Low-embodied carbon building envelope
Electric car charger ready
Project Team
Design-Builder: Travis Douglas & Team, Future & Sons
Energy Rater/Verifier: David Berg, DSB Energy
Structural Engineer: Larsen & Landis
Solar Provider: Solar States
Photography: Sam Oberter
Awards
2021 AIA Pennsylvania: Honor Award
2020 AIA Philadelphia: General Built, Merit Design Award