The National Preservation Conference is this week in Tulsa, Oklahoma. Staff members from around the National Trust for Historic Preservation will be blogging from the conference and sharing their experiences. Today, Barbara Campagna, Graham Gund Architect of the National Trust for Historic Preservation, is reporting on one of yesterday’s educational sessions.
We developed an Education Session at the National Preservation Conference specifically to address the intersection between the National Trust’s Sustainability Initiative and its Modernism + Recent Past Initiative. Held on Wednesday morning in Tulsa, “Rehab Solutions for Aging Moderns”, featured case studies on some of the most iconic modern heritage in America. William Dupont, AIA, San Antonio Conservation Society professor and the former Graham Gund Architect of the National Trust discussed the philosophical approaches developed to guide the interpretation and preservation work at two of the National Trust’s modern sites – Mies van der Rohe’s Farnsworth House in Plano, Illinois and Philip Johnson’s Glass House in New Canaan, Connecticut. David Fixler, FAIA, LEED AP, design & preservation principal at Einhorn Yaffee Prescott Architects & Engineers, discussed intriguing approaches to rehabbing the curtain wall for the IUOE headquarters in Washington, DC and some innovative lighting techniques at Hilles Library at Harvard. And Raymond Pepi, president of New York City-based Building Conservation Associates (BCA), discussed the complex details of rehabilitating the Saarinen-designed curtain wall of buildings at GM’s testing center in Warren, Michigan.
Background on the Initiatives – Why They Matter
The goal of the Trust’s Modernism + Recent Past Initiative is to unite emerging popular interest in preserving the recent past with proper preservation practices through the promotion of continued use and sensitive rehabilitation of these structures. And our Sustainability Initiative promotes the reuse of buildings, the reinvestment in older and historic buildings, the greening of the existing building stock and the respect of historic integrity as the means to addressing climate change. The major intersection between these two initiatives is one of the greatest challenges we face – according to a 2003 Department of Energy report, 55% of America’s commercial building stock was built between 1945 and 1990. And the most inefficient buildings are those built during this same period. Given that almost 50% of the greenhouse gas emissions from the US come from the operations and construction of buildings, the only way we are going to make a demonstrable impact to the reduction of greenhouse gas emissions is through the greening of our modern heritage – most of which are not stellar icons like those discussed in this session.
Some Design Ideas That Might Just Help
Glass Houses of the National Trust
Bill Dupont set the stage for the later case studies by discussing the conflicts inherent in developing a conservation philosophy for buildings from the modern era:
Are they different from our traditional buildings and do they deserve a more nuanced approach? A resounding yes -- from both the previous and current Graham Gund Architects!
Are these icons of 20th century International Style architecture treated differently from other types of historic buildings? Yes, they don’t age like other buildings. They don’t look good with patina. Yet patina proves that they were used, meaning people lived in these homes.
Do they have special problems other buildings do not have? Assemblies, details and use of materials tend to be unproven, at least at the time they were built. These structures were created almost in the manner of a prototype; in the automotive world they use the term concept car, and the manufacturer hand builds one to see how it will look and run. Plus, these experimental materials were often hazardous – like plate glass which is a serious life safety hazard.
How flexible are Modernist Buildings for rehabilitation to serve new uses? Many are not so flexible, the designs are quite tight and thus do not do well with even slight visual changes. There is no place to conceal improvements. Change of use is problematic and thus a threat to survival of this architectural type.
The conservation objective at The Glass House is to restore and conserve the property as it appeared during the final years of Philip Johnson’s life as an active architect, approximately 2000 – 2003, and before his years of declining health when he stopped playing an active role in the design and maintenance decisions at the Glass House Estate. Why focus on this period? Why not preserve to 2005? Over the 56 year period of Johnson’s life at the property, the appearance changed dramatically as property holdings were expanded, new buildings added, sculptures installed and removed, and landscape purposefully altered. The choice to display the physical appearance of the site to the 2000 – 2003 period recognizes that the design grew over time, always attaining a higher level of perfection with each change.
The Farnsworth House needs a slightly different approach. Farnsworth Philosophy: Preservation/ conservation treatment to the December 2003 appearance (the date when the house ceased to be privately owned) is the best approach for the historical interpretation of the Farnsworth House because it allows the history of the site, including stories of the two owners, Farnsworth and Palumbo, to be told with clarity and accuracy. The treatment approach recognizes that the whole history of the property prior to December 2003 has significance, while at the same time the approach allows the period of greatest historical significance – Mies van der Rohe’s involvement with the project that culminated in 1951 – to be fully interpreted. The historical significance of Farnsworth House is broad and preservation of it in its current form does not limit significance to any single date in time.
Both of these approaches are controversial. Some have said that the significance of Mies’ intent rather than the house as actually built is more important. We disagree. As the National Trust for Historic Preservation, we believe it is our duty to tell the many-layered stories of our sites as they were built, not as we might wish they were built. These conservation treatment approaches are what we are using today to make decisions about repairs to the curtain walls and the building systems.
Changing a Curtain Wall – Aesthetics & Energy Efficiency
The IUOE Headquarters, designed by John Burgee (Philip Johnson’s partner), received a re-imagined curtain wall, partially because the owner was tired of their old look and partially to improve the energy efficiency of the building. Built in 1957, the building is not a listed landmark and the owner never considered that its design was significant. The architect, EYP A/E, made the case for its importance – in terms of design, sound original technical approach and the inherent sustainability of keeping original well built and designed building fabric. After evaluating many options, including keeping it as is, the curtain wall was updated, but by keeping the original structure, it would seem to be reversible. The internal weeping system was cleaned during renovation. Stainless steel curtain wall cladding was maintained and cleaned. The original 1/4” insulating green glass was replaced with 1’’ insulating glass panels. New stainless steel stops were installed to accommodate 1” stainless steel stops as well as fire safety insulation. And the original ¼” spandrel panels comprised of a metal sandwich system with porcelain enamel finish was replaced with spandrel glass to match the glass panels with porcelain enamel finish. Yes, the look of the curtain wall is different, but the bones of the structure remain and the majority of the original materials remain.
Changing a Curtain Wall – a Tax Credit Project
The rehabilitation of Manufacturing Building B-West at the GM Technical Center was one of the largest tax credit projects ever, at $1 billion. In this case, the curtain wall was replaced largely because of the studies that indicated a new double glazed curtain wall would almost certainly provide a much greater energy savings for the building. And this is one of the key issues that makes modern heritage so inherently un-green. According to the same DOE study referenced above, in our traditional buildings with wood windows, the greater percentage of energy loss is not through the windows, but through the attics, the walls, ductwork and chimneys. Windows account for only 10% of the energy loss. But it’s the reverse with our modern curtain wall buildings. We can insulate the attic or basement to improve energy efficiency in traditionally-designed buildings, but what can be done to improve the efficiency of all glass walls in buildings where there are no attics or basements? So, here we deal with issues of authenticity almost exclusive to the modern era buildings – is it the concept that’s important or the actual fabric? Obviously the National Park Service agreed with BCA that it was the concept and that removal and replacement of the original curtain wall was acceptable.
Each of these case studies is probably worthy of its own book. What they depict is that the questions are complex and probably every answer is controversial in some manner. But each of these decisions was reached with sound preservation methodologies and if one thing is certain in this brave new world of modern heritage preservation it’s that while the materials and assemblies might be experimental, evaluating all of the options may just give you different conclusions than what you would expect with a traditional building. And in the name of energy efficiency and greenhouse gas emissions, authenticity just may have a different definition too.
-- Barbara Campagna