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Constructing Green

By Monica Ponce de Leon

Before becoming dean at Taubman College of Architecture and Urban Planning, I was a professor of architecture at Harvard University were I taught design studios; lecture and seminar courses on topics, including digital technology and the history of design; and an introductory course on the environmental impact of material selection and application. I am also a practicing architect and as such, I have dealt with the struggle to do the right thing on real projects, in real time, with real budgets and real constraints. As someone who has a foot firmly planted in academia, and a foot firmly planted in practice, through this essay, I wanted to address the design of objects and buildings, and where I see the challenges for the future, as well as the opportunities.

But first let’s review some facts that have now become common knowledge: buildings are one of the heaviest consumers of natural resources and account for a significant portion of the greenhouse gas emissions that affect climate change. In the U.S. alone, buildings account for 38% of all CO2 emissionsi. Buildings represent almost 40% of U.S. primary energy use and 75% of all U.S. electric consumption while they consume 14% of potable waterii.

Perhaps less discussed, but no less significant, is buildings’ share of material consumption and waste output. The EPA estimates that 170 million tons of building-related construction and demolition debris are generated annually, with 61% coming from nonresidential and 39% from residential sourcesiii. This represents 30% of all waste output in the United States (2003 numbers reported in 2009). Similarly dramatic, is that buildings use 40% of raw materials globally.

This is, of course, not surprising. From the onset of industrialization, material production in the various design fields—from industrial design to the design of environments and buildings—has had and continues to have a devastating effect on the planet. So given the magnitude and complexity of the problem, how can designers participate in the solution?

The answer to this question is complex. Building is at the center of many disciplines, and therefore no one field can provide effective alternatives. To address the environmental impact of buildings will demand a revolution where many fields will be required to think differently about their missions, their histories and their purposes. We will also need regulatory mechanisms that ensure change in the market place. We will be dependent on access to innovation and information so that designers, owners and users can make informed choices.

Today many designers see third-party certification systems as the only viable solution to the environmental impact of buildings. Third-party certification systems and organizations have become increasingly streamlined, recognized and respected. LEED rating, for example, assigned by the U.S. Green Building Council (USGBC), has undergone a revolution in just over ten years. The program has grown to cover about 70,000 projects, from six volunteers on one committee to hundreds of volunteers in 78 local affiliates.

Despite its success, LEED has fundamental flaws that expose the limit of third-party certification. For example, negative points are not part of the system. In theory, one could do something terrible for the environment, garner points through other means, and still have a LEED-certified building. Or, for example, LEED only helps to compound the very complex issue of transportation of materials to the site: local production is not always best, despite its immediately apparent benefits. There are some strong arguments in favor of large-scale, centralized production in some industries.

For instance, energy-intensive production such as steel and glass manufacturing are more efficient and less polluting in midsize-to-large plants than they tend to be in small, community-scale operations. Similarly, the manufacture of some energy-saving products, such as window glass with low-e coatings, requires highly developed equipment that is not economically viable on a small scale.

Despite these limitations, LEED remains an effective tool for informed designers who want to make a difference. I have experienced this first hand in my practice. In the Macallen projectiv LEED certification enabled us to incorporate environmentally sensitive strategies into the design, not only because our client wanted to build a better building, but also because LEED certification allowed him to send a clear message (Figure 1). LEED certification served as a marketing tool. Without LEED the incentive might not have been there.

The real problem with LEED lies elsewhere. As I write this, the USGBC boasts that to date the count of LEED-certified projects world-wide is 64,604. While this number might seem impressive, it should be cause for dismay. LEED certification needs to be placed in a larger context. In 2009, in just one month the average number of buildings built in the United States was 66,250. LEED certification can hardly be considered a success.

The challenge is clear. Despite the hype, the excitement, and the best intentions, a volunteer system will never be as effective and have as much impact in transforming the way we build and manage buildings as actual legislation. Despite its extraordinary rate of success, the environmental impact of LEED certification at this time is negligible. Only legally bound regulatory statutes have proven effective in producing tangible, wide-spread change.

The solutions to many of the environmental challenges that pertain to buildings are close within our reach, particularly on the energy front. Advances in the design of building envelopes have placed within our grasp a substantive reduction of the environmental impact of new and existing buildings. The digital revolution has given us the tools to address energy as well as water consumption in buildings. The North House, by Geoffrey Thün and Kathy Velikov, is a great model of what is currently possible. We need to design buildings that take into account that the computer revolution took place and use software as a means to control environmental quality, energy and water consumption within existing and new buildings.

The North House is a research prototype that competed in the U.S. Department of Energy’s Solar Decathlon in 2009, where it placed fourth. It employed two primary technological systems using feedback and response mechanisms: a Responsive Envelope, which reconfigures in response to changing weather conditions, and a custom developed Adaptive Living Interface System (ALIS), which provides detailed performance feedback and system control to the inhabitants, equipping them with informed control of their home (see page 12). Over the course of one year, the home is able to produce up to 6600kWh of electricity beyond what it consumes, and it is able to feed this additional power back into the energy grid.

We need to examine why the means to reduce energy and water consumption in buildings has advanced in research institutions but lags behind in the construction industry. While the digital revolution moves forward at previously unimaginable speed, and digital technology is now deeply embedded in our daily lives, its application in buildings remains in the dark ages. Smart buildings have been the subject of sophisticated research, but little has actually been built. Traditional market mechanisms have failed. It is evident that only performance requirements reinforced by legislation will ensure a fundamental transformation of the industry. The issues of material consumption in buildings and waste output by the construction industry represent complex problems affecting the environment with difficult histories.

Let’s take a look at the selection and use of particular species of wood in American furniture. The use of oak as a common material at the end of the 19th century has traditionally been linked to the Arts and Crafts Movement’s call for honest indigenous materials. But a closer look at material history reveals a different picture. Until the 1890s most designers disliked oak as a primary wood because of oak’s open coarse grain. Walnut was the material of choice. However, at the end of the century walnut was practically depleted from Midwest forests, and therefore it was scarce and expensive. The resurgence of oak was due to this scarcity. Oak was abundant, so American cabinet makers developed methods to treat oak that de-emphasized the grain and darkened it, in a way making it close to the look of walnut.

By the 1910s, as the supply of large oaks declined in the Midwest, oak lost its prominence, and the furniture industry began to harvest trees in the South making poplar, maple and birch the woods of choice. This cycle of “popularity” and “depletion” is one that persists even today, but now at a global scale. This story illustrates how the various fields included under the rubric of design have had a tremendous impact on the degradation of the environment. Whether in the production of objects, buildings or interiors, more often than not, design has been at the center of human interventions that have negatively affected particular ecosystems on a global scale.

How to address the problem of material consumption remains one of the most pressing problems of our time. Today, despite the proliferation of information available to us about materials, the right solution in material selection is hardly apparent. Let’s take plywood, a very common material. If you look at its embodied energy, plywood remains one of the most sustainable materials for the production of buildings and furnishings.

Plywood is a dramatically more efficient use of material than wood for buildings and furnishings (Figure 2). Its laminate structure was engineered to provide great strength with very little matter. Plywood is typically 1.8% binder by weight. Very few types of glue can be used to adhere thin layers of veneer together, and only those with higher molecular weights can be used without penetrating the ply layers. Until the mid-20th century, vegetable and animal glues were used. With the advent of formaldehyde-based binders, plywood manufacturers almost exclusively switched to the new, cheap, and waterproof phenol formaldehyde (PF) and urea formaldehyde (UF) resins.

PFs are dark in color and utilized primarily for exterior and sheathing applications. Off-gassing is minimal once the curation process is finished, but like all formaldehyde-based products, PFs are a known carcinogen. On the other hand, UFs are light in color and used in furniture-grade plywood. UFs continue to off-gas throughout their lifecycle, posing a health risk to both laborers on the production end and end-users, but are far cheaper for the manufacturer. In short, both types of plywood are potentially harmful to human health. Current alternatives to these glues include soy-based binders and PVAC adhesives (like Elmer’s glue). A number of manufacturers and research institutes remain in the research phase of product development, but at least one major plywood company, Columbia Forest Products, carries a soy-based adhesive, which it sells at a premium. This is just one example of the complexity of material selection in building.

Let’s consider the use of wood as a primary material in building. Wood products comprise 47% of the manufactured materials in the U.S. and consume only 4% of the total energy for manufacturing raw materials. When you look specifically at a structural member, let’s say a beam, this becomes even more apparent (Figure 3). However, an analysis of the same material from another point of view gives us a potentially different answer. Deforestation accounts for 1/5 of total global carbon emissions and is most threatening in the tropical regions of the world. Industrial logging accounts for almost 1/3 of deforestation world-wide. Since export and domestic timber are only 16% of that 1/3, on the surface it does not seem that the building and product manufacturing industries are having a great impact on deforestation. However, the furniture, interiors and building industries are the primary users of tropical hardwoods, and it is in tropical deforestation that damage remains significant globally in terms of species diversity, environmental health, and cultural destruction.

To combat deforestation, third-party organizations have again developed standards for responsible practice. The most widely recognized of these organizations is the Forest Stewardship Council (FSC). FSC certification allows consumers to know that the wood products they are purchasing have been logged from a sustainably-managed forest. As a designer, FSC wood is an easy choice, but one with limited impact. FSC forests account for 5% of the world’s productive forests (July 2009), according to the FSC. As successful as the FSC has been, volunteer, market-driven initiatives are slow to take hold and effect change. We need legislation that will ensure that compliance with standards for best practice become the norm, rather than remain the exception.

Parallel to the implementation of statutory laws, addressing the challenge of waste and consumption in buildings will require the fundamental transformation of construction practices. Today’s building industry came into fruition during the industrial revolution, and has remained virtually unchanged. At the turn of the 20th century, construction methods were conceived for ease of assembly, at a time when materials seemed abundant and plentiful. It is in the 19th century that standardization of materials across large geographic areas came into being, forever transforming the way that buildings are produced.

The consistency of dimensional lumber or “modern” brick sizes and their implications for construction are very much part of the reality of building today. These new techniques came into being without the critical input of those outside the building industry, propelled almost exclusively by short-term economic forces with unexpected societal and environmental consequences. For example, the efficiency of assembly of dimensional lumber, enabled by the wide-spread use of platform framing, resulted in the boom of the lumber industry, but by the end of the 19th century most forests in the American Northeast had been depleted.

Despite their enduring history, conventional building practices can no longer be sustained. Standardization and efficiency need to be re-conceptualized in the service of material economy. A new building industry needs to emerge with ease of disassembly as its primary goal. New material standards and construction techniques need to be developed that will enable us to easily transform our buildings as our needs change, and which will easily allow materials to be re-used when a building is taken down.

Recent advances in digital technology have laid a fertile ground for this wholesale transformation. Parametric software allows for complex variations to emerge out of repetitive systems, and digitally guided fabrication enables material efficiency. We already have the capacity to design for disassembly—this should become the catalyst for new building practices that address contemporary needs while anticipating environmental consequences.

Monica Ponce de Leon is Dean of the Taubman College of Architecture and Urban Planning at the University of Michigan.

This paper was presented at U-M Ross School of Business for the Erb Institute for Global and Sustainable Enterprise’s conference.