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Citylight Exterior Rendering


Religious Assembly, Early Childhood Education
Adaptive Reuse, Historic Deep Energy Retrofit
30,000 SF
Philadelphia, PA: Manayunk

Built circa 1850 on the banks of the Schuylkill River, the Roxborough Mills building is being transformed into a home for Citylight Church. This project examines the challenges of renovating a 175-year-old building, navigating Federal and Local Historical registers, and marrying these complexities with carbon goals. The building program leaves the ground level unoccupied while the second floor will include a 500-seat assembly worship space, prefunction areas, office space and both adult and early childhood education facilities. The project incorporates building science, life cycle carbon and operational costs into a broad conversation about historic preservation. It is modeled to use one half the embodied carbon of comparable new construction and with a future 66 kW rooftop solar PV array it is modeled to use one fifth the operational carbon compared with the regional average for this typology.

Citylight Axon


Historic Deep Energy Retrofit

Philadelphia and Federal Register of Historic Places

Native landscape restoration

Building Geometry

Heat Loss Form Factor: 2.4

Window to Wall Ratio: 17.4


Building Metrics

Predicted Energy Use Intensity (pEUI): 35 kBtu/sf/yr (as designed)

Predicted Energy Use Intensity (pEUI): 15 kBtu/sf/yr (with addition of future rooftop solar PV array)

Predicted Embodied Carbon (modeled): 393 CO2e (A1-A3 Cradle to Gate)

Building Envelope

Slab on Grade: Existing to Remain

Floor/Ceiling: R-42 Min.
Above Grade Walls: R-23 Min.
Roof: R-30 C.I.

Windows: U-Value 0.20, SHGC 0.32

Skylights: U-Value 0.17, SHGC 0.26


Building Systems

Power / Fuel Source(s): All electric
Renewable Energy: Solar-ready for addition of future 66 kW rooftop solar PV array
Heating & Cooling: Air-cooled, heat recovery, variable refrigerant flow (VRF) heat pump
Ventilation: Centralized Energy Recovery Ventilator system

Hot Water: Heat pump water heater

Low-embodied carbon building envelope
LED lighting

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