SETAC Globe - Environmental Quality Through Science
  17 February 2011
Volume 12 Issue 2

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Ecological footprint

Measuring the consequences of the SETAC North America meeting through ecological footprint analysis

Bruce W. Vigon, SNA Scientific Affairs Manager

Sustainability requires that utilization of resources for satisfying current needs not compromise their ability to support the needs of future generations. Nature can restore renewable resources at a certain rate, yet humans often consume them faster than their replacement rate. Mankind, through creativity and ingenuity, can develop substitutes that replace or supersede non-renewable resources. Being aware of the consequences of various resource impacting activities is essential to promote sustainability practices. The Society of Environmental Toxicology and Chemistry defines its mission as supporting the development of principles and practices for protection, enhancement, and management of sustainable environmental quality and ecosystem integrity. Each year, SETAC North America holds a meeting for several thousand members and guests to discuss research progress in environmental science and to promote professional networking. One aspect of these meetings that has been gaining attention over the past 5 years is to try to minimize the environmental imprint of SETAC meetings on local, regional and global systems while maintaining the positive financial and social contributions.

Sustainability concepts typically address three dimensions or aspects --- environmental, social, and economic. The Society meetings bring an economic boost to the host city, helping to provide local financial benefits to businesses and their employees. Annual face to face meetings also bring social benefits – obviously to meeting participants, not only from the professional interchanges but also travel and cultural value. The host cities also benefit socially through direct expenditures and word of mouth.

However, along with the positive aspects of these meetings comes travel by participants, increased use of utilities (i.e., water and electricity), and increased production of waste. An ecological footprint (eco-footprint) is a way to account for resources and examine the sustainability of human activities. Specifically, eco- footprints quantify human-ecosystem relationships by assessing how much biologically productive land and sea area is necessary to maintain a given consumption pattern.1 Ecofootprinting is a calculation procedure to convert the resource consumption and land occupancy of the activity into a measure of the biologically equivalent productive space (global hectares, gha) to provide the resources which a population or activity consumes and to absorb the wastes it generates. In 2006, the average biologically productive area per person worldwide was approximately 1.8 global hectares (gha) per capita. The overall U.S. footprint per capita was 9.0 gha.2

1Reference: Wiedmann T; Minx J; Barrett J, Wackernagel M. 2006. Allocating ecological footprints to final consumption categories with input-output analysis. Ecological Economics 56: 28-48.
2Reference: Wikipedia

This year’s meeting in Portland provided an opportunity to compute an ecological footprint for an event at a meeting location known for its sustainability programs at both the municipality and venue levels. Details on specific sustainability practices at the convention center may be found at

The most accurate calculations of the eco-footprint of an event are based on actual meeting-specific data. Although preliminary estimates and partial data were available during the lead up to the meeting and gave an indication of where the major areas of impact would occur, it was decided to wait and use the measured or recorded information as much as possible. Data used for this year’s calculations were obtained from SETAC North America records and the Oregon Convention Center. Additionally, assumptions and extrapolations were made where direct measurements were lacking or incomplete.

Table 1Data on space allocation/usage, utility consumption, waste generation, recycling, and general sustainability practices were obtained from the venue.3 These inputs are summarized in Table 1.

3Venue information provided by Brittin Witzenburg, Sustainability Coordinator for the Oregon Convention Center.

Data on hotel accommodations were obtained from SETAC housing records and scaled to allow for a percentage of participants not staying in the SETAC hotel block. The seven hotels in the block were assigned into one of four categories: Luxury, Midscale, Economy, and Green. A small percentage of room nights (slightly under 3%) was designated, based on travel information provided, to two categories that do not contribute to the footprint, either residents or those staying with friends/relatives. A total of 7,500 room nights were so allocated. The tabulation of accommodations, by lodging type, is shown in Table 2.4

4The assumption on hotel nights for the Baltimore, Montreal and Milwaukee calculations was that all participants stayed five nights. In Portland, the average number of room nights per attendee was calculated from bookings with an adjustment for out of block reservations and families traveling together.

The ecofootprint inputs for the food and fiber (the latter mostly items sold in the SETAC store) categories were determined from actual convention center menu items/pricing and store sales, respectively. Each of the several dozen menus to be served the meeting were broken down into percentages by food category or type, for example, diary, meat, beer, soda, etc. The food item dollars were then scaled within each type to account for food and beverages not provided by SETAC through the convention center directly. These scaling factors to account for other food purchases (either restaurants/cafes inside the Convention Center or externally in area restaurants) are assumptions since actual data for expenditures of meeting attendees for these other meals were not available.5 Food categories, as a percentage of the total and absolute dollar amounts are shown in Table 3. Store sales were dominantly fiber. Paper and various textiles contributed the vast majority (92%) on a monetary basis to the category total, with small additional percentages of plastic, metal, and glass.

5This approach differs from that used in previous meetings where per capita per diems for food were allocated by standard USDA menu composition factors for various meal types.

Table 2Table 3SETAC registration data were used for the number of participants, as well as the distances and modes of travel. Travel distance information was scaled proportionately from the number of participants who filled out the survey during registration (about 1,600) to the total registered (2,289). Distance ranges indicated by registrants were selectively verified by checking home locations in the SETAC membership database and computing exact mileages with MapQuest and WebFlyer. This computation result was used to assign a midpoint value within each range for the transport contribution by that mode. Carbon offsets were available for purchase both online and on site. Each $10 offset is equivalent to 1,681 lb. of CO2. The total CO2 quantity offset was converted into miles of jet travel offset (approximately 161,000) and credited against the totals used for the footprint calculations. A summary of these transport inputs is provided in Table 4.

Table 4Local transportation inputs were both calculated and estimated. It was expected, due to the proximity and ease of use of the MAX light rail and the convention center to the hotels, that the majority of local mobility would be by either the light rail or walking. Small amounts of transport via other modes (personal car, bus, etc.) were added for local residents and field trips for the spouse/guest and special programs. It is not known how local transport contributions, other than via personal cars, were determined for previous meetings.

Results were calculated using the Event Ecofootprint Calculator (Advanced), provided by the Victoria Environmental Protection Authority, available at The conceptual flow of materials, energy, and revenue incorporated in the footprint calculator is shown in Figure 1.

Results from the Baltimore 2005, Montreal 2006, and Milwaukee 2007 SETAC NA meetings were available for comparison.7 Other than the differences noted above, the input data generation methods and computational model were identical.

Results and Observations
Results of the calculation show that the total ecological footprint of the meeting was 1,055 gha. Per capita, based on the actual number of meeting participants, the consumption is 0.46 gha, or a little more than a quarter of the global per capita annual average! Breaking down the total footprint by activity (Table 2) shows that the largest contribution of a little less than 71 percent comes from transportation to and from the meeting, even with the carbon offset. The food and fiber contribution is the second most contributory at just over 29%. The remainder of the activity categories contributed only 0.15%.

Figure 1These results are directionally similar to the calculated ecological footprints for previous meetings, which also found that the greatest impact came from travel to the meeting followed by the production, transport, provision and final disposition of food and fiber items. It is interesting to note, on an absolute basis, that the footprint values for Portland are about 41% lower than for Baltimore and 19% less than for Montreal. The per capita numbers for Portland are similarly about 40% lower versus Baltimore and 35% less than for Montreal.

6Zahner, H. and S. Klaine, 2008, “The Ecological Footprint of SETAC NA Meetings: Making Meetings More Sustainable”, Poster presentation at SETAC North America meeting.
7Thanks to Holly Zahner of the FDA and Steve Klaine of Clemson for the data and results from earlier SETAC NA meetings. Data used for previous year’s calculations were collected from SETAC North America, the Baltimore Convention Center, the Palais des Congres de Montreal, and the Milwaukee Convention Center.

This observed time trending is likely associated with even higher levels of sustainable activities (recycling, green power purchasing, and public transportation/pedestrian travel) at the local level in Portland. However, two factors in the historical data also are contributory to the comparisons. As mentioned above the average number of room nights per participant at the previous meetings was assumed to be five, while the Portland number was calculated (closer to 3.3). A second factor was even more dominant. Long distance transport calculations resulted in mileage numbers that were about 25% higher on a per capita average for Montreal versus Portland. Because this contribution is so significant, focusing attention on getting the most accurate numbers for the calculations (not a trivial matter) as well as meeting location choices is really important. Finally, the sales of offsets should be ramped up.

It seems that making it clear that, although we are not likely to stop having face to face meetings, trying to reduce the contributions from our fossil fueled transportation systems to and from our annual get togethers should be encouraged (incentivized?). Or, we shift travel to other modes than aircraft and encourage the airline industry to continue increasing the efficiency of their equipment. Question is, how much are we as consumers willing to help pay for those changes?

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