CATHERINE CROFT is director of The Twentieth Century Society, based in London. She was formerly a historic buildings inspector at English Heritage and architectural adviser to The Theatres Trust.

HUBERT-JAN HENKET is an architect from the Netherlands. He is founding chairman of Docomomo International and a winner of the World Monuments Fund Knoll Modernism Prize.

JOHANNES WIDODO is co-director of Tun Tan Cheng Lock Centre for Asian Architectural and Urban Heritage at the National University of Singapore and a member of modern Asian Architecture Network (mAAN).

They spoke with SUSAN MACDONALD, head of Field Projects at the Getty Conservation Institute, and JEFFREY LEVIN, editor of Conservation Perspectives, The GCI Newsletter.

CATHERINE CROFTWe were founded in 1979 as the thirties Society, in response to the threat to buildings of a broader period—buildings of the 1920s up to the outbreak of the war. From the beginning, we campaigned for the preservation of buildings of all styles and types, although in the early years, many of the people involved were particularly interested in deco buildings or revival styles. One of our first campaigns was to preserve the 1920s Lloyd's Building in London by Edwin Cooper. We weren't very successful, and part of the building was incorporated into Richard Rogers's new headquarters for Lloyd's in the mid-1980s. Now we have actually campaigned to have the Rogers building itself listed. that shows a huge movement in the type of buildings we're interested in. We're a charity with a small government grant, and the rest of our funding comes from individual members from all sorts of backgrounds. From the beginning, we've had more architectural historians working with us rather than architects, and we now have about two thousand members. The majority of our income comes from subscriptions and from organizing tours, including foreign trips. The profits we make are fed back into the campaign work.

MACDONALDWould you say that your main objectives are advocacy and education?

CROFTCasework is central to what we do, and that consists of advocacy on government policy, as well as campaigning for specific buildings. We also have a broad role loosely defined as education, which is changing public attitudes regarding the buildings that we care about.

HUBERT-JAN HENKETThe development of my country at the start of the twentieth century was very much involved with modernity. Modernity created our social democracy and produced a variety of important buildings in the Modern Movement. Modernity is about achieving freedom and independence for all through progress in science and technology, an idea that started in the Enlightenment. In that period, the market economy came about, which itself led to the notion of constant innovation. That remains characteristic of our dynamic, fluid society—everything has to be continuously new. The other basic characteristic is temporality—things are not meant for eternity but for a short period of time. That is what modern architecture is about. These purpose-made buildings are totally different from those more neutral buildings, which were built for a long period of time. The Dutch government asked me to do a survey of modern buildings in order to develop a proposal for what to do with them, and I carried this out with my assistant at the time, Wessel de Jonge. We considered it a pity to waste this knowledge and thought we should communicate with people in other countries to have an intellectual debate about this weird paradox: keeping throwaway buildings for eternity. We started in 1988 and invented the name Docomomo—Documentation and Conservation of the Modern Movement. At our first conference we started with twelve countries—a thirteenth joined at the conference—and we drafted a constitution. From the start, we tried to bring architects and architectural historians together, because architects on their own are rather subjective. At the moment, we are in sixty-three countries.

MACDONALDIs it true to say that what distinguishes Docomomo from other conservation-related organizations is that it was partly about sustaining the ideology of modernism?

Photo: Courtesy of Catherine Croft
With more modern buildings, there may be more questions to ask and more subtleties to understand, but it's not a totally different process.

HENKETThat's a tricky question. As architects, we had the intention to stimulate the ideas of the Modern Movement because it's a way of thinking. The architectural historians didn't like promoting that way of thinking, so we put devotion to the ideas into a separate document, which we called the Eindhoven Statement.

JEFFREY LEVINJohannes, yours is the newest of the organizations. Can you talk about its inception?

JOHANNES WIDODOBack in the year 2000, before the establishment of mAAN, several friends from different Asian countries met at a conference in Guangzhou, China, and we started discussing the state of modern architecture in Asia, including the demolishment of colonial buildings as the result of rapid economic growth. Some thought there was nothing wrong with demolishing colonial buildings because they reminded us of colonization, occupation, and cruelty. Others said, "No, it's part of our identity." And that raised the question: what is our identity? As we looked into our own curriculums, we were shocked to find that Banister Fletcher's A History of Architecture was still used in many schools in Asia as one of the textbooks for architecture— a book that considers Asian architecture as nonarchitecture. So what were the alternatives? Well, we had them in national languages—Chinese, Japanese—but not in English.

So we agreed to meet again in Macao in 2001 at a more formal conference, where we had the opportunity to connect with people from UNESCO, Docomomo, and ICOMOS. At our founding conference in Macao, we put together declarations that emphasized the principles of Asian modernity. There are many modernisms in Asia because we are cosmopolitan. Our history is layered, not just linear. Because of this layering, we produce a very hybrid and diverse architecture. To prove that, we embarked on a project called the Comprehensive Inventory to inventory our own buildings. We didn't trust the existing registries made by governments, which only serve a certain agenda. We wanted to go into the crowd and use students as a cheap army to go to different cities and do a comprehensive inventory.

We are also working together with other organizations. Ron Van Oers from UNESCO World Heritage in Paris has brought us together with Docomomo, ICOMOS, and UNESCO. We use these coalitions to generate awareness. We also sent a message to Docomomo—before you move into Asia, please rethink the state of our architecture. We are so diverse, it is impossible to pinpoint Asian modernity. Our modern architecture is not the same. Your template may not fit into the Asian situation.

WIDODOThe issue is miscommunication. Some subscribe to Docomomo—other ones do not, and there's some internal conflict even within different countries. So when you organized the "Other Modernisms" conference in Turkey, we purposely organized a similar conference in Tokyo in 2006 called "Our Modern—Re-appropriating Asia's Urban Heritage."

HENKETI disagree. You give the impression that we have one fixed view on modernity. In 1996 we had a conference in Bratislava— you were there—titled "Universality and Heterogeneity." In Holland we used modernity to establish social democracy. In Hungary they used it in the early twentieth century as part of becoming an independent country. In Brazil they used it for nation building. The 2006 Docomomo conference in Turkey was called "Other Modernisms." Although we started off as being Euro oriented, it doesn't mean that we did not evolve rapidly. May I add that the conservation approach I am presenting here only represents my personal vision, created by the environment I am living in.

MACDONALDIsn't the difference that mAAN looks broadly at places that represented a wider interpretation of modernity, while Docomomo was unabashedly talking about the architecture that represented modernism? Their scope of interest is different.

HENKETWe were interested in understanding what modernity, at least in our part of the world, really was, and in how we could safeguard it for future generations. Like it or not, what we are talking about is a paradox if you accept that modernity has to do with temporality and—up to now—the constant new.

MACDONALDCan I challenge you on that? Maybe it's terminology, but when I think about some buildings that are manifestations of this idea, I can't believe that an architect would have thought of these places as temporal. Unitè d'Habitation has a solid permanence, as does some of Le Corbusier's later work. It's solid, it's heavy, and it's monumental.

Photo: Pieter Henket
We were interested in understanding what modernity … really was, and in how we could safeguard it for future generations.

CROFTLe Corbusier—specifically in regard to the Unitè— described enjoying the idea that the concrete would erode back into the sand that it's made of.

MACDONALDRight, but we at the GCI talked to a lot of architects about how they saw their work, and they always said they were hoping that their buildings would endure—that they had added something to society today and in the future. They often surprised me regarding how endurance of their buildings was really important.

HENKETIf you believe in a dynamic society, which is the whole idea of modernity, then you've got a problem.

CROFTThen maybe what you need to do is to feel that your buildings can adapt and change in how you use them.

HENKETYes, but in the postwar period, hardly any client wants to invest in flexibility. John Habraken in the sixties started this movement about flexibility and investing in the future of a building in Holland, in the United States, and in Japan. But his efforts failed because nobody wants to invest more in a building than he is sure to get back in the future.

CROFTThe buildings that have proven most flexible over the years are not ones that were built with that in mind. The Victorian terrace house is staggeringly flexible, while the same is not true about some Rogers and Foster buildings where it was intended that the interiors could be reconfigured.

HENKETModern buildings are mostly custom designed because functional requirements have become ever more specific and change rapidly. Traditional buildings in general had loadbearing structures that were neutrally positioned and dimensions that were oversized. These characteristics make adaptive reuse relatively simple.

MACDONALDYou can make the point that at the end of the twentieth century compared to the beginning of the twentieth century, there were a lot more building typologies. There is a question of sustainability when those uses have changed. Even if buildings appear adaptable, there are many more types to start with— which means a wider range of challenges that need solutions.

CROFTSometimes there isn't a solution. Structures like nineteenth century maltings buildings are really specific and tricky because the floor-to-ceiling height is not big enough for much else.

WIDODOIn many Asian contexts we have this so-called shophouse or town house typology, which exists everywhere from India to China to Southeast Asia. It's very flexible and can be adapted for different kinds of functions. You can just buy one unit and develop a hotel, and so on. But you also have the experience of mass housing in Singapore—building development blocks. These are only able to sustain types of uses for maybe twenty years, and then they have to be demolished and rebuilt. As a result, Singapore is moving into the process of demolishing and rebuilding different types of public housing. The buildings themselves are not flexible because their size is so massive and difficult to modify. Smaller forms are easier. Medium-density high-rise is preferable to high-density high-rise.

MACDONALDHow different are the conservation approaches in different parts of the world? Is it possible to have universal principles for the conservation of modern architecture, or is it specific to different parts of the world?

HENKETWithin Docomomo, you see a different approach occurring toward conservation. At first we talked about restoration, the architect's original intent, and icons. In some places we are moving away from the icons because most of them have been done, and we are now embracing a broader meaning of conservation, ranging from basic restoration to reuse. In my opinion, the main goal of restoration is keeping something of the cultural value, whereas reuse is primarily a functional matter, and maintenance is primarily a technical thing. Maintenance, reuse, and restoration all belong to the same notion—trying to be more sophisticated with the existing building stock. There is one common thing, and that's ecology. We have to rethink our approach from continuously building new things to reusing what we've got.

CROFTBut hasn't that always happened? Since the dissolution of the monasteries in Britain, people have reinterpreted and reworked existing buildings.

HENKETI still come back to the fact that an industrial society wants production—because if it doesn't produce, the economy stops. Production means temporality and the constant new.

MACDONALDYou are suggesting that the basic premise of conservation and sustainability is universal. But how do you go about that?

HENKETThrough awareness politics and legislation.

WIDODOI think we agree on one point—that conservation should be viewed as a way to manage change, rather than a way to freeze artifacts. It's not possible to freeze things because everything changes, and if we want to keep buildings from an ecological point of view, we need to recycle. Adaptive reuse is one way to go.

MACDONALDJohannes, you mentioned that you thought that the Asian context was somewhat different. We know that in conservation practice in Asia, how you make conservation decisions differs due to the importance of intangible values.

WIDODOYou cannot avoid change. The intangible is what is permanent, while the tangible is nonpermanent. That is probably the simplest way of describing how we treat architecture. Architecture is the manifestation of our needs and our beliefs. When looking at temples like Borobudur, we consider them as texts—texts to convey Buddhist teachings. When the Chinese build a pagoda, it is actually a presentation of that philosophy. Similarly, we replace the pagoda from brick to concrete or steel, as long as it continues to function as a text.

CROFTBut those intangible things are the hardest things to maintain, particularly through a change of use. For example, there are market buildings in Brixton in South London that were to be torn down. They were initially rejected for listing because they were not thought architecturally significant—but then were listed for their role in the history of the local Afro-Caribbean community. Listing has saved them, but they now house restaurants where yuppie Londoners come for a night out with a slight edge. You struggle to buy yam anywhere now. The markets are losing their significance for the community they were preserved for.

LEVINOther than the temporality issue that's been raised, is there really a distinction between conservation of modern architecture and older architecture?

CROFTI don't think there is any fundamental difference.

WIDODOThat's why we say that the purview of mAAN goes from the Silk Road until today.

HENKETThere is a distinction, as far as the material is concerned. An industrial product is completely different from a handmade product and not meant to last. If you go to a building site today in our country, there's not a craftsman around. Everybody is just fixing things. It's a totally different trade. Craftsmen are rare.

CROFTWhy is that such a fundamental difference from a Victorian architect going on site and seeing bricks being laid instead of timber and frame and wattle and daub construction?

HENKETBecause in Victorian times, a bricklayer was cheap and materials expensive. Now the materials are cheap and labor costs are high. Today we talk about a building industry. We don't talk about a craft anymore. Society has changed, so our goals and requirements have changed. The materials we use, the way we combine them, and the ways they behave are very different.

MACDONALDJohannes, do you think that the conservation of modern architecture in Asia is part of the continuum of conservation practice, or is it different from how you approach the conservation of other eras?

WIDODOWe see modernity as a continuum. It's not based on periodization. We can't possibly make a periodization of the typologies, for example.

LEVINDoes the difference in building materials have consequences for conservation?

HENKETYou can't even get the materials any longer. Often industrial products will not be on the market after twenty years.

CROFTBut you can't get some older materials. You can't get green oak easily to do timber frame, you can't get certain mortars, you can't get a lot of stone, and you can't get certain glass.

HENKETGlass is a fair example, but stone isn't—because you can find the quarries. For the Barcelona Pavilion by Mies van der Rohe, they went back to the same quarries that Mies got his material from.

MACDONALDIf you think of buildings constructed of a stone like magnesian limestone—which are found in parts of Europe— you can't get that material anymore. But even if you could, you wouldn't want to use it because you know it won't last. It leaves you with the same challenge as dealing with modern materials.

HENKETA tree will grow. Industrial products are man-made. We have changed the building industry, and therefore the way we conserve buildings will be different. The original material is a difficult item in industrialized buildings.

WIDODOCan we still apply the concept of authenticity to modern buildings?

MACDONALDMaybe authenticity means something different with respect to modern buildings.

CROFTThere's always that discussion, "Oh, if this product had been available, then the architect would have used it." This is said with postwar buildings in particular. We would never dream of saying that when conserving a Georgian town house.

HENKETIt is a very different task to conserve modern buildings. In our country, conservation architects are slowly disappearing. An architect who is ethically and technically well trained can also talk about buildings thirty to fifty years old. So conservation is becoming something different. We should train architects to appreciate the life cycle of buildings and to learn how best to maintain, reuse, and transform them, as well as learn to design new buildings. It's not either building new buildings or conserving buildings—it's a combination.

CROFTI don't think a fundamentally different approach is needed. The first stage of working on any conservation project is gaining an understanding of the building's history, including the history of its use. With modern buildings, there may be more questions to ask and more subtleties to understand, but it's not a totally different process.

MACDONALDPeople might need more help knowing how to do that, as they may not be familiar with the process.

CROFTYes, but then there are far more documentary sources available on the whole to assist with that. Understanding the specifics of past use is critical but sometimes gets forgotten.

LEVINBeyond the use of industrial materials, are there other challenges specific to the conservation of modern buildings that distinguish them from the conservation of other built heritage?

HENKETThey're less flexible.

CROFTWell—sometimes they are and sometimes they're not. Sometimes they're basically huge open spaces.

HENKETBut on the whole, they are less flexible. Most modern buildings are economically designed so the load-bearing structure can carry a certain amount but never more than absolutely necessary. Besides, the dimensions of spaces are minimal.

CROFTThere's nothing less flexible than a medieval parish church whose significance is in its whole volume and precise layout, along with the fittings and the surfaces. Compare that to a postwar public housing estate. With the latter, there are actually quite a lot of areas where you could make fairly radical alterations.

HENKETYes, but in the past, buildings were meant to last—and because they were meant to last, they were much more neutrally designed than we design them nowadays. Don't underestimate the influence of ever more specific requirements.

MACDONALDDo you think that was conscious in the past? Isn't that just how buildings were built, and so the result of it is that they're more enduring?

HENKETConscious or not, what occurred from the eighteenth century onward is that buildings became more specific. Today the economy of the building is the overriding factor. Things are calculated so people don't build more than absolutely necessary. If you want to change it to other purposes, you're limited to what those purposes might be. We also change our building requirements rapidly for safety, environmental, and comfort reasons.

MACDONALDBut the need to adapt buildings to new requirements is the same, whether it's from the fourteenth century or the twentieth century.

HENKETChangeability depends on the building's size. If there is sufficient space, you can fit in all sorts of things, as long as the performance of the materiality fits the new requirements.

MACDONALDOne problem with midcentury modern houses is that they were often very economical and small, and now everyone wants more bedrooms and bathrooms and a bigger kitchen. And there are all those office buildings that were designed to incorporate new technologies like computers but didn't anticipate that they would now require a fraction of the surface space they needed before. So yes, there are design issues for some building types that make them problematic to adapt. But whether they constitute a fundamentally different problem is still the question. What would you say are the outstanding challenges that we still need to address in order to successfully conserve modern buildings?

CROFTConcrete repair. We haven't got enough well-documented case studies about what to do, and we're struggling to reach a consensus on the best approaches. I've been teaching at West Dean College, and I'm conscious of telling people to essentially experiment, rather than providing them with proven solutions.

WIDODORegarding materials in our case, it is timber, brick, plaster, and roof tiles.

HENKETI would add plastics and aluminum to concrete—all the new materials. And climate control.

CROFTYes, we need good case studies that show how to improve the environmental performance of even pretty standard twentieth-century buildings, such as the classic postwar school. How do you make them function better environmentally without losing the original windows that are a huge part of those buildings?

MACDONALDOne thing that is different about conserving modern buildings is who is doing the work. The people doing the conservation might be design architects, who come to it through their interest in modernism. They might be well versed in the ideas behind it, but they're not well versed in the general tenets or practice of conservation. On the other hand, you've got conservation architects who may be good with traditional materials but now are faced with building types and materials they're not familiar with. What skills do we need to address these issues? Do we need specialist training?

Photo: Courtesy of Johannes Widodo
Conservation should be viewed as a way to manage change, rather than a way to freeze artifacts.

CROFTThere's a question of whether we want to produce a separate profession—a restorer of twentieth-century or Modern Movement buildings—or do we want to broaden the education of conservation architects. I think the latter, because applying the same philosophy across all building conservation makes sense.

HENKETWe have to be careful introducing more specialists into the building industry. Thirty years ago, we made buildings with five people around the table. Nowadays, with most of my projects, it's fifteen to twenty people. With so much specialization, nobody is taking overall responsibility for the original idea. This is happening in conservation as well. We need to train our architects to be broad and be able to undertake renovation projects and to know about maintenance and restoration. It's not just about conserving buildings. It's about conserving environments. I think in the United States that is happening, with the renewed interest in urban cities. Suburbanization is stopping and people are moving back into the cities. We need the type of architect who thinks as much about the overall built environment as about the buildings—about the past and the future.

LEVINIs there anything else that we need to do in terms of advancing the conservation of modernism?

HENKETEducate the public at large. It's happening already, but should be done more. Educating children is extremely important. Help people become aware of their environment. In traditional societies, that was obvious because you were there always— whereas in our mobile society, that is different. Yet you have to.

CROFTIt's becoming easier to do that. For a long time, the Thirties Society was a fairly inward-looking club, but with the Internet we're about to put all our notes from our tours online, so you can download them and take yourself on a walking tour. If we had more resources, we would be able to do iPhone app tours. Getting public consensus is part and parcel of our casework because only when government feels that a public consensus is developing will it take the initiative on listing a building.

WIDODOPublicity is important, whether it's in magazine articles, advertisements, as the backdrop for a television show— anything that helps to promote awareness and makes old buildings look cool, so that people want to be there.

LEVINWith the last twenty-five years of development of organizations focused on the preservation and conservation of modern architecture, what kind of progress do you think we've made?

CROFTThe big shift has been broader public appreciation of the buildings of the period, but also a feeling that it is appropriate to look analytically at architecture that is not widely popular at the moment. We should be ahead of that fashion curve, trying to make sense of what to keep. When we started proposing postmodern buildings for listing, most people said, "They're horrible," and "Absolutely, no." At some point we will be listing the best of those postmodern buildings, but it isn't happening yet. Still, there has been a huge shift. The value of the recent past is definitely accepted.

HENKETAnd that went quicker than we thought. In Docomomo there's a change in approach from the icons to the ordinary. The basic question is how to keep the intangible in the reuse and renovation process—because that's really what matters.

WIDODOWe're moving into more youth education, hands-on workshops, and training on sites, in cooperation with corporations, governments, and stakeholders. We're also working with all these different organizations because we now have a common purpose—to prevent destruction of our heritage from rapid development and greed, which have become real threats. We put a lot of emphasis on rejuvenating the organization itself by giving opportunity to people under forty to take leadership and to use social media and the Internet more intensively. The youth are starting to feel it is their part to rebuild knowledge, and to create approaches based on the experience that they have. So the seeds we put down twenty years ago are starting to grow.