Skip To Content
External Article

Faith & Form, Volume 52, Issue 3, “Cathedral of Sustainability,” by Jeffrey Murphy

Cathedral of Sustainability

Faith & Form: The Interfaith Journal on Religion, Art, and Architecture

Published in Volume 52, Issue 3

By Jeffrey Murphy, FAIA

St. Patrick’s in New York adopts state-of-the-art geothermal efficiency while preserving history.

Light is an essential religious metaphor and also an elemental ally in architecture, revealing the intricacies of color, space, and form. An extensive renovation of New York’s St. Patrick’s Cathedral, completed in 2017 (and this year celebrated with national honors from the American Institute of Architects), illuminates how faith and architecture become two hands joined in prayer. Leading a world-class team of experts, our firm MBB (Murphy Burnham & Buttrick Architects) shared a common purpose with the trustees of St. Patrick’s: restoring the iconic architectural work as a global symbol of the Catholic faith while at the same time establishing its modern operations at the vanguard of sustainability.

The story begins in the mid-1800s with John Hughes, the first Archbishop of the Archdiocese of New York, who hired James Renwick, Jr. to design a cathedral on Fifth Avenue that would elevate his brethren to God. At its completion, St. Patrick’s Cathedral stood as the tallest building on Manhattan Island. Today, the building’s spires reach only modest heights in Midtown, yet the landmark’s loftiness has been renewed following its all-encompassing, $177-million-dollar renovation.

Diocesan leaders, workling closely with us, identified a range of significant needs and laid out their comprehensive conservation campaign by 2006. Plaster was peeling. Spalling and joint failure in the masonry were visible, and the roof was leaking. Interior and exterior surfaces were darkened by pollutants, sunlight could barely penetrate the cathedral’s famous but dirty stained-glass windows and oxidized protective glazing. On top of that, an array of new opportunities in worship, visitor experience, and programming were considered desirable aspects for the future of this faith community.

Yet as historic structures often impose, more complications faced the project team. The original architectural plans were incomplete and undigitized, and the existing drawing sets did not accurately describe the finished cathedral. To plan effectively before undertaking the renovation design, the design team undertook a months-long research and documentation process employing laser technology to generate an accurate survey of St. Patrick’s Cathedral as it had been built and improved over the decades. This fairly unobtrusive process revealed a further and (as it turned out) most important challenge: Accommodating in one of America’s best-known houses of worship five million annual visitors, all enjoying an open-door policy.

Designing to Improve the Worship Experience

As a design prerogative, worship enhancement was a core objective of the archdiocese leadership. The renovation concepts were focused on making the worship experience more functional, inspiring, and liturgically current. Collaborating with clergy leadership, our firm faced the tasks of preserving the exquisite marble, slate, metalwork, ornamental plasterwork, decorative woodwork, cast stone, and stained glass. In a miraculous merging of mission and function, these highest-order goals also supported a long-term aspiration for the archdiocese: to make its operations less costly, more efficient, and even a model of resilient, sustainable design for the decades to come.

For example, repairing the masonry structure and eliminating fenestration gaps set the stage for incorporating passive design principles that would minimize moisture infiltration and improve thermal performance. But certain building elements had to be replaced, such as original Tuckahoe marble that the design team ultimately sourced from residential backyards in nearby Westchester County.

Other design initiatives seem less obvious for a historic landmark but proved equally important. For example, in service to the cathedral’s role as a beacon of welcome, openness, and sanctity the design team conceived glass entry doors to couple with massive bronze portals opening the main entrance to Fifth Avenue. The minimalist, quiet sliding doors allow ample visual connection to the exterior while reducing outdoor noise indoors by 80 percent and dramatically increasing interior daylight. Moreover, this retrofit avoids the past practice of leaving the portals open, cutting energy losses and the infiltration of exterior pollutants.

Daylight now floods the interiors thanks to various improvements. The project team added skylights above all side chapels, which significantly illuminate the aisles. Monumental structural glass walls now acoustically enclose the Lady Chapel–an intimate worship space added to the original building that had seen its serene atmosphere diminished by noise from the heavily trafficked nave. Restorations of the magnificent stained glass by leading conservators returned them to their original intended functionality, admitting more filtered and colored daylight inside.

Once the conservation experts repointed the light marble, repaired and repainted the plaster ceiling, and restored new daylighting sources in key areas, light filled the cathedral revealing original details that had long been obscured. Cleaning the interior, restoring the original paint palette, and enhancing daylight in the space returned the look and feel of the lightness described in the New York Times when the cathedral first opened in 1879.

Transformative Planning and Design

In parallel with this work, a mini-revolution was taking place in the conception of St. Patrick’s Cathedral as a place of comfort and as a user of energy. At the project’s 2006 inception, the Trustees tasked us with organizing a full evaluation of the existing heating, ventilation, and air-conditioning (HVAC), and plumbing systems. We saw an opportunity to do this with an eye towards improving facility performance and resiliency, and encouraging leadership in long-term sustainability. During this needs-and-conditions assessment, it became clear that the 1960s-vintage air-conditioning equipment was outdated and beyond its useful life. So too were existing steam heating pipes that clanked during cold mornings, providing inconsistent performance.

A holistic and comprehensive solution was the ultimate objective, with the added challenge that any proposed solution would have to avoid disrupting the historic fabric or daily worship. These were paramount design goals. Yet the team also considered aesthetics, longevity, redundancy, total cost of operations, and green-building opportunities. Ultimately, it became clear that a geothermal system offered the most benefits and the best overall solution, even as it raised thorny questions: Could the wells be drilled on the grounds of this historical landmark? How would the retrofit impact the community and cathedral operations? Could enough redundancy be built into the system in order to ensure performance throughout the year (at the time, only a few established institutions were employing large geothermal systems in the New York metropolitan area)?

The answers looked promising and the potential benefits of this approach became quite clear. For example, a conventional HVAC approach would have necessitated a large fan wall next to the cardinal’s residence on Madison Avenue, exposing mechanical elements to the public and clergy alike. Such an installation would also mean modifying the cathedral architecture, further complicating the city’s Landmarks Preservation Commission’s approvals process. Most concerning, the conventional HVAC changeout would negatively impact the daily experience of millions of visitors.

So with a profound sense of broad-mindedness and foresight, the archdiocesan leadership elected to integrate geothermal technology into the restoration of the cathedral. In conjunction with construction manager Structure Tone, Inc., and working closely with Zubatkin Owner Representation, we and our engineers undertook a detailed feasibility study examining costs, cathedral activities, and the municipal approvals processes. In the end, the trustees and clergy leadership, local community groups and officials, and the Landmarks Preservation Commission supported the design and construction of what has been called the largest geothermal project ever built in Manhattan. Furthermore, this decision reflects a long view of architectural stewardship: Geothermal systems are not only sustainable and resilient, but quiet, low-impact, and promote efficient space allocation. For a long-term owner, they have a low total cost of operation. With an installation cost of $35 million, the investment was deemed appropriate for an institution anticipating its needs for the next 150 years.

The geothermal system also became a key ally in earning a 30 percent reduction in the building’s annual energy use and a variety of honors for design and sustainability achievements, including a recent COTE Top Ten Award from AIA, its most prestigious sustainable design award. The completed system has the capacity to generate 240 tons of air conditioning and 3.2 million BTUs per hour of heating.

Geothermal and Water Conservation

Within this thoughtful, long-range framework of preservation, improvements, and operations, creative construction sequencing helped deliver the work efficiently while reducing up-front costs. A rolling scaffold supported the restoration of stained glass and the plaster ceiling. The nave was always kept clear to allow for 18 weekly masses and other activities.

The geothermal work was designed and staged to minimize impact during and after the work: On both sides of the cathedral, well consultants P.W. Grosser directed drillers Stothoff Engineering to drill 9-inch-diameter spaced boreholes. The ten wells descend to a maximum of 2,250 feet into Manhattan bedrock. Running pipes through the undercroft and unused crawl spaces increased the utility of existing interiors without disturbing historic detailing, millwork, and stone, and important sightlines throughout the spaces. Equally important, the geothermal system designers, Landmark Facilities Group, seamlessly integrated 14 large-coil air-handling units behind custom grilles in the triforium gallery, near the south transept and one of two organs.

Efficient use of both space and energy were critical. Repurposing the former basement boiler room created enough clearance for the geothermal plant’s pumps and compressors. A computer system controls numerous independent thermostats that heat and cool different zones. Moreover, a backup system of gas-fired boilers and an evaporative fluid cooler can supplement the system at peak demand. Component selection reflects a long view of high performance: stainless-steel pumps and high-density polyethylene (HDPE) ground loops mitigate corrosion. Durable titanium-plate heat exchangers and a modular design allow individual units to be taken offline to facilitate easy maintenance and contribute to longevity and resiliency of the equipment.

Since coming online, the geothermal system has been so effective at heating and cooling the cathedral that the backup system has never engaged. Annual energy savings are equivalent to 1.7 million tons of CO2, according to actual utility records. As a secondary benefit, the closed-loop geothermal and mechanical systems also conserve water. The cathedral’s system uses only 300 gallons a year, while a cooling tower, if selected, would have required about 3.8 million gallons of makeup water. A bleeding geothermal system would have used 1.3 million gallons. Impressively, ground-source heat eliminates the condensate losses inherent in district steam. Furthermore, the cathedral’s closed-loop system reduces water requirements and minimizes impacts on groundwater, achieved by a dedicated chiller that cools wells during peak demand.

Other water conservation measures further green the cathedral, including newly efficient domestic water and plumbing systems and sustainable improvements to the builiding’s surrounding landscape and urban habitat. Working with RKLA on a plan for the landscape architecture during the geothermal well drilling, the team removed the compacted soils and dense ivy in the exterior gardens. In their place, improved soils and native plantings and trees were added, creating a new and lush site that needs minimal irrigation and absorbs hardscape runoff. A 600-square-foot green roof on a utility entry structure was added, and bluestone walkways and curbs aid pedestrian access. It’s an entire city block with planted perimeter areas of interest to tourists and horticulturalists alike, with varied blooming species, berry shrubs, and seven mature Hornbeam trees. Varied seasonal blooms, a tree canopy that covers 40 percent of the garden area, and fruit production maximize ecological sustainability and attract sparrows, warblers, and robins. The new gardens offer home for squirrels and a healthy, diverse insect population.

Preserving History, Serving Future Generations

History came first in every decision for the St. Patrick’s Cathedral landscape, restoration, and even its new, state-of-the-art mechanical systems, with every effort made to honor Renwick’s original vision and the unique legacy of the landmark’s life (such as rejointing the Tuckahoe marble with mortar matched to the original). One of 18 small altars within the cathedral depicts St. Joseph, patron saint of laborers. Symbolic of the thousands of people who built, improved, and restored this cathedral, this pious figure also recalls how inspired institutional leadership can harness technology and sustainable architecture in stewardship: The results serve more people and undergird an enduring symbol of the faith for years to come. In more current thinking, the work reinforces the Catholic belief in the sanctity of the planet, as Pope Francis has described: “The entire material universe speaks of God’s love, his boundless affection for us. Soil, water, mountains – everything is, as it were, a caress of God.” What humans create also represents an outgrowth of nature, and St. Patrick’s teaches spirituality, theology, justice, and also lessons in sustainability.

On one of the 75 restored stained-glass windows, the architect Renwick is illustrated handing his architectural plans to Archbishop Hughes. It is a wonderful metaphor of how faith and form are like those hands joined in prayer. In this way, the cathedral creates “a tangible sense of the beyond, of the transcendent, of the reverent,” said his Eminence Edward Cardinal Egan, the late Cardinal and Archbishop Emeritus of New York. Along with a successful architectural and engineering solution to serve contemporary needs, visitors and cathedral staff alike might find themselves closer to their inspirations and more comforted in worship. Indeed, this cathedral that was built to give light and comfort to its flock now better illuminates the world’s architectural heritage, too, one that reaches up to the sky as it embraces the earth.

Jeffrey Murphy is a practitioner in cultural, civic, and institutional architecture. He is a partner at MBB (Murphy Burnham & Buttrick Architects), an international award‑winning architecture firm based in New York City.

Back to News