Philly TOD Net-Zero Mixed-Income Residential Housing | Philadelphia, Pennsylvania | 2022

Architects: AECOM
Lead Architect: Francis Cooke
General Contractor: Private
Client: Creative Development Partners
Images: Courtesy of the Architects

This design solution is driven by a strong sense of purpose, to create a living arrangement intended to connect our fracturing society.

These tactics of integration and connection are applied to the physical construction itself. By recruiting untapped resources latent within the urban context (sewer main, subway air pressure flow, cast off building materials from local demolition work, etc.) this project provides maximum social benefit with a minimum of carbon expenditure.

It forms an incisive model for the future of development within dense cities. It addresses resiliency and scarcity. It is a truly Social Infrastructure.
Our society is fracturing because we are losing direct, interpersonal experiences with each other. This loss fuels existing alienation and class divisions.
The proposal is driven by clear (research-based) studies of interpersonal space and its effects on creating stronger social connections. The single loaded corridor atrium parti, specifically scaled, connects all residents implicitly.

Explicit connections are made at the level of programming. There are a host of socially focused spaces accessible to all tenants (roof gardens, daycare, community kitchens, maker spaces, etc.) and most impactfully, the mix of unit types is granular with market rate and affordable units equally mixed on each floor.

These social motivations are given their final architectural form through a form finding process driven by analytical energy modeling. The shape, orientation and enclosure are devised to reduce energy demands.

The proposed construction methodologies maximize recycled content of the structure and cladding in addition to utilizing mass timber systems to curtail the building’s embodied energy footprint.

Finally, onsite, latent energy is harvested with a sewer pipe heat exchange system, a forced air atrium ventilation system driven by subway station pressure differentials and a massive deployable fabric sunshade with integrated PVs.

The challenges of our immediate future are also opportunities for progress. This project is driven by an analytical design approach that focuses on delivering net-zero carbon emissions. Both embodied and operational carbon emissions are tracked.

The base-case total carbon emissions are 17 KgCO^2e/m^2/year. Carbon reductions are made in three distinct steps – energy demand reduction, carbon footprint reduction and energy generation.

Energy demand reduction is addressed by optimizing the building massing, articulating the building façade for daylighting, and refining the thermal performance of the enclosure systems. These steps reduce the total emissions to 13 KgCO^2e/m^2/year.

The most impactful reductions are achieved in the carbon footprint reduction step. By aggressively utilizing recycled content in the structure and cladding materials as well as leveraging mass timber for the upper floors of the structure and cladding, the total emissions drop to 4 KgCO^2e/m^2/year, just inside the range of what is achievable for onsite energy generation. In the final energy reduction stage,they tap the latent heat sink available from an adjacent sewer main line.

They also harness the piston effect of the subway station ventilation to drive air into the atrium spaces. A massive deployable fabric PV array pushes the project to carbon neutral with -0.2 KgCO^2e/m^2/year.