Methodology

How did we do this project?

Jena Utaski (NWS' 20) and Jenny Cooper (Director of Environmental Education & Sustainability at NWS) started this project in the spring of 2018 and continued into the spring of 2020.

In order to create an accurate greenhouse gas inventory we must determine all of the school’s producers of greenhouse gas emissions. The Northwest School’s main producers are from natural gas consumption and transportation. Transportation includes student and faculty transportation to and from school, NWS bus trips, air travel for student trips, administrative air travel trips, and international student trips to/from their home countries.

Once we had determined the largest producers we found the sources that provide information about the amount of emissions they produce. For electricity and energy we looked at Seattle City Light electricity data and Puget Sound Energy bills. For bus trips and air travel, Northwest faculty members kept track of the location traveled to, miles traveled, and mode of transport for each trip. Lastly, for student/faculty commuting and international student travel home we developed and sent out a survey to each student and faculty member asking the distance they travel home and their mode of transport. From this point, we were able to organize the data, and find an emissions factor to calculate the amount of greenhouse gas emissions produced from each category. See table below for details on emissions factor sources, calculations, etc.

Data Years

• 2016-2017 school year: bus transportation

• 2017-2018 school year: faculty commuting data

• 2018-2019 school year: international student flights, student airplane trips, student commuting, administrative airplane trips, and natural gas

In this process, what assumptions were we forced to make?

We have a high degree of confidence regarding our bus, natural gas, and electricity data. All other data we designed surveys to collect, therefore in that data we had to make some assumptions in order to have a representative data set. These surveys required a level of trust in the student and faculty answers. Not only that, but received only a portion of survey responses from the students and faculty members, so we had to assume that the answers we did not receive mirrored those that we did. In addition to that, we made smaller assumptions further along the process. For example, if a student marked that they carpool to school, we assumed that a carpool is made up of on average two students. While we worked hard to make our data as accurate as possible, at times we used our best judgment to make assumptions.

Due to the assumptions we made and the resources at hand, we believe that this inventory is an underestimate of the greenhouse gas emissions that NWS produces annually.