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Red Clay Passive


Single Family Residential
New Construction
3,500 SF
Kennett Square, PA

This project investigates the notion of a Shaker farmhouse in a contemporary, low carbon context. Like the barns that dot its agrarian landscape, the house is simple in shape, absent of ornament, and constrained in material expression. 

Its simple, vernacular form steps down with the sloped site and orients its long axis towards the south, maximizing solar exposure during winter months. Exemplifying a New Carbon Architecture, this house and adjacent outbuilding avoid the inconsistencies and waste of conventional ‘stick-built construction' by using an innovative, wood-fiber-based, panelized assembly system; all above grade wall and roof components were prefabricated within seventy miles of the project site.


As evidence of the design's focus on energy efficiency and reduced carbon consumption, the project achieved PHIUS+ 2018 Source Zero Energy Passive House certification.



Passive House: PHIUS+ 2018 Source Zero Energy Certified (Database Listing)

U.S. Department of Energy (DOE) Zero Energy Ready Home Certified


U.S. EPA Indoor airPLUS Qualified Home

Building Geometry

Heat Loss Form Factor: 1.6

Building Metrics

Predicted Energy Use Intensity (pEUI): -1.87 kBtu/sf/yr

Home Energy Rating Score (HERS Index): -11

Airtightness (measured): 0.05 cfm/sf; 0.72 ACH50

Building Envelope

Slab On Grade: R-25

Below Grade Walls: R-25

Above Grade Walls: R-36

Roof: R-53

Windows: Average SHGC 0.5, average U-Value .14

Skylights: Average SHGC 0.19, U-Value 0.19

Modular (panelized) wood-fiber-based wall & roof assemblies (above grade)

Building Systems

Power/Fuel Source(s): All electric

Renewable Energy: Solar PV array (8.76 kW system size) 

Heating & Cooling: Ground-source heat pump

Energy recovery ventilation

Domestic Hot Water: Heat-pump water heater

Appliances: Energy-Star

LED lighting

Project Team

Builder: Hugh Lofting Timber Framing

Energy Modeling / Prefabrication Specialist: Holzraum

Prefabricated Assembly Provider: Blueprint Robotics

Energy Verifier: DSB Energy 

Photography: Sam Oberter

Awards & Recognition

2023 Phius Passive Projects Design Competition: Source Zero Honorable Mention

2023 CONTEXT: Design Profile | Red Clay Passive

2022 AIA Pennsylvania Architectural Excellence COTE Award

2020 AIA Philadelphia COTE: Net Zero Buildings | Red Clay Passive

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