Photo of the exterior of the Library Company's Ridgway archives

The Library Company’s Ridgway archives, with exterior insulation.

How do you achieve museum-quality environmental conditions and modern energy efficiency in a 1960’s era building?  That was the challenge BWA undertook with our recently completed renovation of the Library Company’s Ridgway building.

The Library Company of Philadelphia is an independent research library concentrating on American society and culture from the 17th through the 19th centuries.  BWA has a long-standing relationship with the Library which began with the renovation and restoration of their Cassatt House, a Frank Furness-designed building on the Philadelphia Register of Historic Places, to provide event space and residences for visiting scholars.  We followed that with a master plan for facilities expansion and archival storage upgrade.

A key objective identified in that master plan was to improve the energy efficiency of the library’s Ridgway building, a 1960’s building designed by Carroll, Grisdale & Van Alen to house a priceless collection of rare books, manuscripts, ephemera, prints, photographs, and works of art dating from the 17th through the 19th centuries.

Insulation and Updated Controls

While studying the existing structure, BWA identified severe envelope deficiencies in the 8-story concrete and brick building.  While attempting to maintain the interior conditions at museum-quality temperature and humidity levels, the perimeter was severely under-performing by today’s standards for air, thermal and vapor barriers.

BWA and the Library Company considered interior insulation and barriers, but found several disadvantages to this design approach.  Insulating the interior surfaces would have required a major disruption of operations,  the relocation of archival materials, and a permanent reduction in usable space.  Additionally, the interior insulation would be discontinuous—allowing energy loss through thermal bridging at the floor slab.

Instead, the project team decided to wrap insulation on the exterior brick and cast stone surfaces to dramatically improve its thermal envelope, an approach BWA had used successfully in earlier projects, (Cyber Village Senior Housing, Connelly House).  In this application, BWA chose to use 5 inches of Expanded Polystyrene (EPS) insulation board to achieve an added R-Value of 21.75

The new insulation wraps completely around the exterior of the building, including the windows, which were significant sources of vapor, thermal and light: all deleterious to archival environments.   Two colors were used in the final surfacing, produced by Sto, to match the existing concrete front and brick sides, honoring the client’s desire to replicate the building’s exterior appearance and complying with the Historic Preservation ACT 106 requirements.

photo of historic text from the Library Company's archives

From the Library Company’s archives

Because the building’s mechanical system was well maintained, the design team decided to take a very careful, custom approach to the HVAC upgrades.  Existing equipment was replaced only if nearing the end of its lifespan or where the payback in increased energy efficiency justified installing new technology.  For instance, in some cases, it made sense to replace motors with VFD (variable frequency drive) capability, assuring immediate savings and better environmental conditions.

The most critical upgrade to the mechanical system was the installation of a new digital control system–controls that will not only improve the system’s efficiency, but also allow the Library Company to optimize the environmental conditions for their valuable archives.   To ensure the resulting HVAC system would meet best practices in preservation, the design team reviewed recommendations from the Image Permanence Institute at the Rochester  Institute of Technology, a leader in sustainable practices for the preservation of images and cultural property.  Then, consulting engineers Bruce E. Brooks & Associates worked closely with mechanical contractor Limbach to integrate a state-of-the-art control system into the upgraded mechanical system.

Though the project was just recently completed, the Library Company has already reported a significant reduction in energy costs for the Ridgway building.