Green Building Performance. Reuse vs Recycle.

Another talk for the quantitatively-inclined at the recent US Federal Environmental Symposium East was “Results of LEED Building Energy Performance Study” by Brendan Owens of the US Green Building Council (USGBC). LEED is a rating system for buildings in terms of their environmental impact administered by the USGBC. A building can earn points within the system for energy and resource efficiency, use of renewable materials, recycling, diversion of construction waste from landfill, etc.

The talk concerned an interesting study commissioned by the USGBC and completed by the New Building Institute. The key question was how did buildings that received LEED certification when they were completed, perform once they were in operation. 121 certified buildings, representing 22% of the total number, participated in the study. (Note: these were the ones who responded to an invitation, sent to all, to participate in the study, and so do not form a random sample.) The results were that in general, LEED buildings were 25-30% more energy efficient than non-LEED buildings. The data were pretty variable and unpredictable (e.g. some very highly rated buildings performed near the bottom). It seemed like some of the variability could have been mitigated by controlling for building type within the study. Buildings serve different functions. A data center is going to have a different energy use profile than an office building. The results are being used to shape the next version of the LEED rating system. The study is available here.

All told, the symposium showcased many good initiatives and programs. One thing that seemed to be lacking, however, was something along the lines of the cradle-to-cradle viewpoint, with a more critical take on recycling, for instance, and more emphasis on avoiding many of these problems at the outset by more thoughtful design and reuse. There was some evidence of this, as in a different USPS talk about how the amount of hazardous materials they generate has been cut by 90% through green purchasing. But in other cases, recycling programs and green electronics purchases were trumpeted with far less said about reusable over recycled items (such as bottles) and upgrading equipment versus purchasing new environmentally-friendly equipment (like computers). Nevertheless, many steps in the right direction are being taken.

Ecological Design

Book: Ecological Design by S. Van der Ryn and S. Cowan, 1996

A chief concern of this book is to bring ecological concerns into the world of design. Ecological design as defined by the authors is “any form of design that minimizes environmentally destructive impacts by integrating itself with living processes.” [p18] The first part of the book makes the case for a new kind of design and introduces concepts that appear throughout the rest of the text, such as appealing to nature for design inspiration. In the second part, the authors lay out their five principles of ecological design, which are roughly: 1) solutions in a place can arise from the nature of the place, 2) undertake ecological accounting, 3) design with nature, 4) involve the community, and 5) make nature visible in people’s lives.

The chapter on ecological accounting contains a number of interesting examples such as the tracking of a tomato and its packaging from their origins to the consumer, an accounting of resources and wastes in the San Francisco area, and a number of university resource flow accountings. It also has a product breakdown based on an earlier writing of Cradle to Cradle’s Braungart that is similar to the biological/technological split in that book. In fact, this book discusses many of the same or similar ideas as Cradle to Cradle, although Ecological Design was published about six years earlier. The “design with nature” principle outlined in the subsequent chapter has much in common with the goals of industrial ecology. That chapter also describes a number of interesting examples such as plants whose roots filter heavy metals out of soil or factory runoff. This use of examples to support the well thought out principles of ecological design is a strength of the book. On the down side, the writing is sometimes prone to broad generalizations about the ubiquitous design ills imposed by city planners, engineers, etc. But overall it is an interesting and often inspiring work.

The book is primarily about sustainability and design. As such, the relevance to Operations Research and Sustainability is fairly general. But there are a couple of items with more obvious connections. One was a description of the California Waste Exchange’s “Directory of Industrial Recyclers and Listing of Hazardous Wastes Available for Recycling” (see http://www.westp2net.org/hazwaste/app/appd.html). This directory lists recyclable hazardous wastes, and available surplus materials and recalls the Glassey and Gupta LP analysis of matching various kinds of paper waste with recycled paper production (see References). The other item was this quote: “Classic economic notions of optimization and efficiency are no longer adequate to describe the ecological complexity surrounding us.” (p141) The challenge that the OR practitioner faces in many realms, of applying what can be inherently reductionist techniques to complex problems is particularly acute when the subject matter is the environment.

Paper on WEEE returns strategy

The paper summarized below is part of an upcoming EJOR issue on closed-loop supply chains, mentioned earlier. It includes an integer program and connects to cradle-to-cradle ideas with its emphasis on “Design for Dissassembly and Recovery”.

Strategic response to EEE returns: Product eco-design or new recovery processes?
R. Zuidwijk and H. Krikke
in European Journal of Operational Research
doi:10.1016/j.ejor.2007.08.004
Notes: This paper looks at possible strategic responses of electronics industry firms to WEEE. As the title suggests, strategic approaches are divided into product design and processing of recovered products. Strategies to handle WEEE can be implemented at either end, or both simultaneously. On the design side (or “eco-design” as the authors label it), “Design for Disassembly and Recovery (DfX)” and “Product Data Management (PDM)” are considered. The inclusion of DfX is what links the paper to the cradle-to-cradle philosophy. For instance, one of the goals of DfX listed in the paper is “to make material fractions more homogeneous so they can be separated more easily”. Under PDM, products maintain information about themselves over their life-cycles, providing industry with data on the installed base and consequently on the recovered products.

After a nice overview of WEEE, the authors outline the strategic responses and discuss some background literature. X-ray technology is mentioned as one of the methods used to assess the content of recovered products (this was also mentioned in the batteries paper summarized here). The authors claim that a key contribution of the paper is that it considers the integration of eco-design and advanced process technologies. They make the interesting observation that a reason the overlap has not been studied much may be that, both in industry and academia, these two areas are studied/managed by people in different disciplines/locations in the supply chain.

Within product/module/component recovery, the basic decision to be made is between recycling and remanufacturing. The problem is modeled in different ways depending on the level of product information being assumed. Under full product information, the problem is posed as an integer program. The objective is to maximize profit, which consists of remanufacturing and recycling revenue (some of which may be negative) minus disassembly costs. Constraints are primarily flow balances from products to modules to components across the various processes, but also include WEEE recovery quotas for given materials. Under partial information, the IP is replaced by a set of decision rules. In the absence of any information, a “default strategy” is used.

The models are applied to the recovery of computer monitors under differing levels of information and with different combinations of strategies on both the design and recovery ends. As might be expected, DfX comes out favorably because it aids in remanufacturing as well as in reducing recycling costs because of its better separation of materials. It reduces the importance of complex processing technologies and information tracking. The authors point on that the IP is fairly generic and can be adapted to other industries.

Compostable Cup

Coffee from a New London, Connecticut shop came in this biodegradable cup and grip. Click on the image for a closer look. Cradle-to-cradle adherents might applaud the notion of throwing the cup on the ground once it is empty, or would the recycled paper that it is made from, with its dyes and chemicals give them pause?

Aritificial Turf from Recycled Tires Releases Gases

Recycled tire crumbs found in athletic field artificial turf were recently found to release into the air significant amounts of four volatile organic compounds. So this is the kind of thing the cradle-to-cradle camp worries about. The tires were never intended to end up in artificial turf.

The study was sponsored by Environment and Human Health, Inc., a non-profit aimed at protecting people from environmental harm, and it was conducted by the Connecticut Agricultural Experiment Station, a state government agency. The report can be found here. Though it is fairly technical, it is interesting to read about the testing procedures. For instance, the crumbs are heated to 140° F, which the authors claim is not unrealistic for them to reach while in direct sunlight on a hot day. In a test to determine whether the harmful gases leach into water, the crumbs are placed in water and agitated for 18 hours. Not being an expert, it is difficult to assess the danger. These are not field tests. Is the amount of the gases being released significant? How dangerous are these compounds? Probably the key message is that more study is warranted. And that is what CT’s attorney general Richard Blumenthal is proposing.

Cradle to Cradle

Book: Cradle to Cradle - Remaking the Way We Make Things by William McDonough & Michael Braungart

The key idea in this book is a design philosophy called eco-effective, in which products, systems, etc. are designed with all of their present and future impacts on human and environmental health in mind. In particular, the idea is for these systems to enrich the Earth and its inhabitants, not deplete and harm them as many current industrial systems do.

While acknowledging the good intentions behind mainstream environmentalism including the popular notion of “reduce, reuse, recycle”, the authors claim this type of approach only slows down the harmful effects of industry, but does not eliminate them. They are critical of much recycling, labeling it “down-cycling” to emphasize that the materials in a good typically go from a higher-end to a lower-end product. For example, plastic bottles are recycled to a lower-grade plastic. In addition, the recycled product may become something the original material was never intended to be. Recycled plastic bottles, some of which release toxins according to the book, can become decks of suburban homes. Another problem with recycling is that it can lock up valuable materials instead of extracting them and returning them to the manufacturer in pure form. As an example of this, the authors describe how when a car is scrapped for its steel, the copper cables in the car are not extracted. This is unfortunate, they point out, because copper is valuable on its own, but weakens the recycled steel in which it is contained.

Following the eco-effective principles, products should be designed to be recycled or up-cycled but not down-cycled. They should consist of biological components (termed “nutrients”) and technological nutrients. Ideally, products should be manufactured in a way that allows these two types of nutrients to be separated. The biological nutrients could be left to biodegrade, while the technological nutrients would flow back to factories to be reused.

The book includes several interesting examples of successful eco-effective design (roof gardens, buildings that function as air ducts, Ford auto factory redesign, etc.), many of which were led by the authors’ company. At times, the book takes on an alarmist tone without providing evidence on some of the claims being made. One example of this is the opening passage about the reader settling into a common chair to read the book while hazardous particles from the chair’s fabric become airborne and make their way to reader’s lungs. In all though, the book is highly thought-provoking and quite interesting.

Though the book is about design, its fundamental philosophy relates to all stages in the life-cycle of a good. As a result, it could impact any models used to develop and recycle products in this way. From an Operations Research perspective, one could aim towards optimal recycling in which down-cycling and the trapping of precious materials are minimized, among other goals. Eco-effective principles are an ideal way to close the supply chain loop. An earlier post here mentioned an upcoming EJOR paper with this feel. It is likely that others of the references on this site include eco-effective ideas as well. I plan to add more about them in the future.

Upcoming EJOR Issue on Closed-Loop Supply Chains

EJOR (European Journal of Operational Research) has an upcoming feature issue on closed loop supply chains. The abstract of the introduction to the issue is available to Science Direct subscribers. It mentions three papers in the issue. The first by Zuidwijk and Krikke has a cradle-to-cradle strategy feel about how much to invest in product design and how much to invest in the processes to handle returned products. This is modeled using an integer linear program and applied to the production of computer monitors. Update: added a summary of the Zuidwijk and Krikke paper to the references section.

Update: It’s out. Navigate to this page and scroll to the bottom.