December 2007 Newsletter

by Gordy Slack

The expression "environmental footprint" does not begin to capture the full impact that a building and its occupants have over time. A building's cradle-to-grave influence on the environment is a shape-shifting and sprawling thing, with tentacles that extend far into the future and all around the world, says Arpad Horvath, Associate Professor in UC Berkeley's Department of Civil and Environmental Engineering and Director of the Consortium on Green Design and Manufacturing.

To calculate that influence, Horvath and his colleague begin by looking at a building's direct impact on its site, its energy use, and its greenhouse emissions. But they also take into account aspects that most designers and builders do not sufficiently think about, he says. These issues include the source of the raw materials out of which the building is made, for instance, and the environmental cost of extracting and then transporting those materials-whether concrete, stone, carpeting, plumbing fixtures, or roofing. The researchers also study the impacts of remodeling and renovating the building over its decades of operation, and even the impact of demolishing the building and disposing of its parts once it is obsolete, many decades down the line.

As part of his efforts to put some teeth into the "sustainable" development movement, Horvath is developing practical tools that will help decision makers in the building business evaluate the real cost of the choices they make.

"Right now the emphasis is on greenhouse gasses and energy use," says Horvath. "Those things are important, but there are other things that do not get attention that may matter just as much." If the building is to be made of stone, for instance, and that stone is shipped from overseas where its extraction, albeit cheap in monetary terms, was environmentally costly, and if shipping that stone requires the burning of huge amounts of dirty diesel shipping fuel, those impacts might outweigh the perceived environmental benefit of making the building of stone in the first place. True, a building whose roof is covered with solar cells may use less fuel to power, but does the environmental cost of manufacturing the solar cells outweigh the energy savings over the building's lifetime? Maybe yes, and maybe no. Providing the tools to take a "scientific and data-driven approach" to determine what is the case for any given project is Horvath's aim.

To make such life-span calculations, he says, it is essential to know how long a building is likely to remain on the scene. "We tend to think of our new buildings as monuments," he says, "presuming, based on the old European model, that they will be around for centuries. But the buildings we are designing today are not likely to be around nearly that long. Most of them will be functionally obsolete in 50 years. We need to take that fact to heart when designing them in the first place."

Making versatile buildings that are not overbuilt and that have interior walls that are simple to reconfigure, for example, can reduce a structure's impact when it comes time for the inevitable remodeling and updating, says Horvath. The more adaptable a building is, the longer it may be productive and the less environmentally costly it will be to retool. Additionally, over-designing and over-constructing a building wastes materials. Twice: once in their acquisition, and once in their disposal when the building is torn down.

Perhaps the hardest part of Horvath's job, he notes, is figuring out what will matter to the environment decades from now. Fifty years ago, few people worried about global warming or greenhouse gas emissions. Architects in the early 20th century could not have imagined that heating fuel would cost what it does today or that the byproducts of our energy use patterns would catalyze climate change. Surely there are environmental impacts that are obscure to us today but in half a century will be plain as day, Horvath says.

"In our lab," Horvath says, "we are trying to put together tools that will allow people to figure out what the comprehensive life-long footprint of a building, or pavement, or transportation will be. Until they can do that, we cannot expect people to make the best long-term decisions."

The tools to make the right decisions are one thing. The will to do the right thing, even when it may be more costly in the short-term, poses another kind of challenge. Iris Tommelein, another professor in Berkeley's Department of Civil and Environmental Engineering, says this willingness to change is really a cultural issue, not a technological one. And the specific culture in question, that of the world of design, construction, and project management, is her area of expertise.

Tommelein runs the Project Production Systems Lab (P2SL), which applies principles of "lean manufacturing" to one-of-a-kind projects. Lean manufacturing is an approach to production, developed over many decades by Toyota, that emphasizes value generation and the minimization of waste, both of materials and worker time.

"Reducing waste of all kinds shrinks a project's environmental footprint," says Tommelein, "even if the immediate incentive is really to save money and resources."

Many of the inefficiencies in building construction arise from the traditional relationships between owners, planners, designers, engineers, suppliers, regulatory agencies, and the dozens of different (sub)contractors on a job, according to Tommelein. Restructuring those relationships so that those in charge have strong incentives to get realistic project expectations, say, rather than just the lowest possible bids, is "very tricky business," she says.

"The whole system of blame assignment needs to be changed," says Tommelein. "We are trying to cultivate a culture that rewards realistic appraisals, cooperation, and truth telling."
One major factor is the current emphasis on individual projects at the expense of long-term relationships, Tommelein says. "We are trying to move from traditional transaction-oriented contracts toward relational contracting," she says. If a contractor's only aim is to win an individual contract, he may feel forced to underbid a project knowing full well that his overruns will be compensated when push comes to shove. But if forging a trusting, long-term relationship with the project owner is valued, then a realistic bid, even if it appears high, will eventually be rewarded.

Cooperation and coordination among sub-contractors minimizes the amount of reworking that needs to be done as well, says Tommelein. Rather than mapping a production schedule based on each sub-contractor trying to minimize his own exposure to liability, the lean approach stresses reality-based schedules that are reliable and keep the project flowing.

"We are very broad in our view of design and construction," says Tommelein. "We start with capital budgeting and making a business case for the owner early in the design process. We work with designers and engineers to design the facility and then with suppliers, manufacturers, fabricators, and contractors to build the facility. Throughout this process, we build in concern about lifecycle and sustainability issues."

By striving for what Toyota calls "mistake-proof design," an aspect of the Built-in Quality Initiative within P2SL, Tommelein notes that time and resources can be shaved off a job and safety performance improves. P2SL researchers design on-site operations, supervisory practices, and work with owners, designers, suppliers, fabricators, and regulatory agencies to systematically improve performance. A new building may have complex mechanical, electrical, and plumbing systems as well as wall partitions to be installed. If the parties responsible for this work coordinate their work through design and construction, the job overall can benefit significantly. "It is not uncommon," Tommelein says, "for contractors to save 20 or 30 percent of labor hours on a construction project by applying lean principles."

While Horvath aims to realistically appraise environmental impact and Tommelein strives to create an efficient process for project delivery, both researchers are trying to reduce waste by reevaluating the process from cradle to grave. "Iris (Tommelein) and I agree that without understanding the supply chain and all the steps that lead up to the making of a building, there is no understanding of the final building itself," says Horvath. "And unless you really understand a building and the processes of making it, there is no way to make it sustainable."

by Gordy Slack

 

Find the demo on Wikipedia Trust at http://wiki-trust.cse.ucsc.edu/

 

A team of engineers led by UC Santa Cruz computer scientist Luca de Alfaro is working on a solution to Wikipidia's central paradox. The online encyclopedia is among the world's ten most-visited websites. The English edition alone has more than two million articles, and about seven percent of all Internet users are said to use the site daily. Unlike other, more traditional reference works whose authority stems from the expertise of hand-picked authors and editors, Wikipedia is a collaborative effort, written by thousands of volunteers, some of whom are experts in their fields and others who are not. Its openness to contributions from anyone with access to the Internet is key to Wikipedia's success, but it is also the site's Achilles' heel.

Mature articles on Wikipedia are, on average, very reliable; some studies have argued that they compete with the Encyclopedia Britannica for accuracy. But because anyone can edit Wikipedia, the integrity of an article can easily be compromised by a malicious vandal or even a well-meaning contributor. Users who turn to the reference seeking an important answer to a specific question, therefore, can never be sure what kind of authority lies behind any particular piece of information.

De Alfaro's solution is a software tool that automatically evaluates and indicates the trust value of each of Wikipedia's billions of words. "We are trying to provide a simple visual guide that shows how reliable the information on Wikipedia is," he says.

In late November, a live prototype of de Alfaro's system was launched with support of both CITRIS and the Wikimedia Foundation, the non-profit that runs Wikipedia.

Underlying the program developed by de Alfaro's team is a reputation system that grades Wikipedia authors. The system assigns, and updates, a numerical value of reputation to each author. Authors start with a low value of reputation, and they gain as they make contributions that are preserved by subsequent authors. Authors' reputations can also lose value, if the changes they make to Wikipedia articles are undone.

"The reputation we compute for authors is a good predictor of future behavior: authors with high reputations really do tend to make longer-lasting contributions to Wikipedia," says de Alfaro.

The trustworthiness of Wikipedia text is computed on the basis of the edits it has received over the course of time – an idea first suggested by a Stanford group led by Richard Fikes and Deborah McGuinness. De Alfaro's system assigns to each word a value of trust derived from the reputation of the author of the word, as well as on the reputation of all visitors who edited nearby text, thereby lending to it some of their reputation.

"When people edit text and leave some sentences unchanged, they implicitly vote for the correctness of the text they have left unchanged," explains de Alfaro. "We are essentially automating the usual process of text revision: for each piece of text, we take into account all the people who revised it, giving more weight to people of higher reputation."

"At the user level," says de Alfaro, "text in clear background is very likely to be accurate, whereas text with orange background is less certain. The darker the text highlighting, the less confident you can be about the quality of the content," he says.

"The things marked in the darkest orange are recent changes by low-reputation authors. Recent changes by high-reputation authors are marked in a mid-level of orange. Text gradually fades back to white as high-trust people review and revise it," says de Alfaro.

"One of the benefits of our system is that it becomes very difficult to surreptitiously tamper with Wikipedia text," says de Alfaro.

The text of articles that have been stable for many revisions appears on a mostly white background; many authors have lent their reputation to it. Against this white background, any recent modification stands out clearly, sending a red flag to users.

"Every recent change, no matter how high the reputation of the author, is still reflected in some degree of orange shading. Nobody can single-handedly create trusted (white-background) information: full trust, or a white background, can only be achieved by collaboration and agreement."

"We made the program entirely data driven," says de Alfaro. "Rankings are not calculated based on human evaluations of authors the way they are on E-Bay, where buyers and sellers grade one another after each transaction." De Alfaro believes that a data-driven approach can be equally accurate and friendlier to contributors, who are not asked to rate each other. In particular, de Alfaro hopes that the lack of personal rankings will avoid ad hominem attacks and help protect the open and collaborative Wikipedia culture.

The Wikimedia Foundation is still deciding whether to adopt the system as an optional overlay for its live site. Even if it does, casual users who prefer to browse without the filter would be able to turn it off and just view the latest text, says de Alfaro.

There are good ethical and cultural reasons to avoid putting human judgment into the mix when evaluating Wikipedia's text, but there is also a resource advantage to applying a mechanical system to the entire site. In a couple of days of processing time de Alfaro's program can read and colorize the whole Wikipedia site and eventually, if it is adopted by Wikipedia and woven into its interface, evaluate each edit and entry as they are made.

 

 

Related site:

Luca de Alfaro’s research site: http://trust.cse.ucsc.edu/

 

The demo on Wikipedia Trust is at: http://wiki-trust.cse.ucsc.edu/