4. Determining Your Carbon Footprint and Emissions Trajectory

4.1 Conducting a Greenhouse Gas Emissions Inventory

While it is not necessary to conduct a campus GHG inventory to reduce GHG emissions, a GHG inventory is an essential step in assembling a CAP. ACUPCC participants agree to conduct a greenhouse gas (GHG) inventory within one year of signing and then to update that inventory at least every other year. This frequency for renewing a GHG inventory is appropriate for all campuses pursuing GHG reductions.

A GHG inventory will provide a general diagnosis and a measuring stick to determine success or failure in your efforts to reduce GHG emissions. The inventory does this by establishing and quantifying your campus’ carbon footprint in terms of metric tons of carbon dioxide equivalent per year (MTCO2e/yr). Metric units are used because of the international nature of GHG emissions accounting. GHG emissions are quantified in terms of “CO2e” or carbon dioxide equivalent. There are a number of greenhouse gases whose atmospheric concentrations are increasing as a result of human activity. These GHGs include carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons. Carbon dioxide from burning fossil fuels and destroying forests is having the greatest impact on climate, and, consequently, emissions volumes for combinations of GHGs are generally given in terms of equivalent amounts of CO2.

An inventory is also an awareness raising tool. It allows green campus advocates to equate energy-wasting activities to the problem of climate change by showing their consequences in terms of GHG emissions. This can be a big wake up call. Making this connection can motivate behavior change.

The first time you calculate your annual GHG emissions it makes sense to do so not only for the most recent year for which you have data but also for a number of preceding years in order to reveal your GHG emissions trajectory. By comparing inventories of successive years, you can see additional trends which will help your analysis.

These steps are involved in conducting a GHG inventory:

  • Determine the scope of your inventory, i.e. which categories of emissions you will be including:
    • Scope 1 emissions: all direct emissions, i.e. from sources owned or controlled by your institution
    • Scope 2 emissions: indirect emissions from purchases of electricity, steam, heating, and cooling
    • Scope 3 emissions: all other indirect emissions upstream and downstream
  • Determine your time horizon, i.e. the years you plan to inventory
  • Select your GHG inventory tool (see section 4.2)
  • Determine what input data you will need and gather that data
  • Run the inventory spread sheet
  • Analyze the results

GHG emissions scopes 1, 2, and 3 are defined by international protocols. Your campus climate commitment and CAP should specify which categories of GHG emissions you are committed to reducing and to what extent. In making a commitment to climate neutrality, ACUPCC participants have agreed to eventually fully mitigate the following categories of GHG emissions and thus should include them in their GHG inventories:

  • Direct combustion of fossil fuels by equipment which is owned by and controlled by your school such as boilers, furnaces, fleet vehicles, etc. (Scope 1)
  • So-called “fugitive emissions” from on-campus releases of CFCs and HCFCs and on-campus releases of methane from farm animals (if you have them) (Scope 1)
  • Purchased electricity, steam, heating, and cooling (Scope 2)
  • Commuting by students, faculty and staff to and from campus (Scope 3)
  • Business air travel paid for by or through your school (Scope 3)

Many institutions choose to include emissions from other GHG sources in their inventories since counting and discussing them increases the likelihood that efforts will also be made to reduce them. These other sources of GHG emissions include waste disposal, embodied emissions in the products and services your college or university buys, outsourced activities, contractor owned vehicles, and even line losses associated with bringing electric power to your campus. Of the above, the most easy to calculate may be the GHG emissions associated with waste disposal since the Clean Air-Cool Planet “Campus Carbon Calculator” (see the "Clean Air-Cool Planet GHG Inventory Tool" section of this guide) is already set up to do this. The embodied energy in product purchasing is undoubtedly huge but can be quite difficult to calculate.

The GHG inventory tool is essentially a spreadsheet which will calculate your school’s carbon footprint once it has all required input data. The raw input data you will need generally falls into these categories:

  • Purchased Electricity
  • Purchased Steam / Chilled Water
  • On Campus Stationary Sources (energy generation)
  • Transportation (commuting, air travel, campus fleet)
  • Agriculture (fertilizer use, animal waste)
  • Solid Waste (incinerated, landfill)
  • Refrigerants and other Chemicals
  • Offsets (Renewable Energy Credits purchased, composting, forest preservation, local offset projects such as paying for boiler conversion at a local K-12 school, etc.)

Obtaining this data can be like conducting a scavenger hunt. You will need to identify campus sources of data and then arrange for them to provide it to you. The ACUPCC Greenhouse Gas Inventory Brief offers these excellent suggestions on gathering input data for your inventory:

  • Keep a journal of the process and sources of data, including who you contacted, when you contacted them, their responses
  • As you identify the correct data sources, record these in a legacy document to facilitate future inventory processes
  • Give people deadlines for gathering information
  • Where possible, create systems for future reporting, such as reporting forms to be collected by the climate action team annually
  • Foster positive relationships along the way
  • Where data is incomplete or unavailable, gather the information you can and note gaps to fill in later
  • Encourage better record keeping in the future

For more information about conducting a GHG inventory, see the ACUPCC Implementation Guide and Clean Air-Cool Planet's Campus Climate Action Toolkit.

4.1.1 Data Collection and Calculation Method for Commuting and Air Travel

More so than for most other categories of GHG emissions, those associated with commuting and air travel tend to be based on assumptions. To make these assumptions, some raw data is needed but it tends to be indirect in nature. For guidance on data collection and calculations for these two categories of emissions, see "Guidance on Scope 3 Emissions: Commuting" by Niles Barnes and "Guidance on Scope 3 Emissions: Air Travel" by Julian Dautremont-Smith.

For commuting, your goal is to estimate the number of gallons of gasoline that is consumed by this activity. To do that you will need to estimate total miles driven and make an assumption about average fuel economy. A fair number to use for the latter is the U.S. average fuel economy for all cars and light trucks, estimated by the U.S. Environmental Protection Agency to be “an uninspiring 20.8 mpg”. Coming up with total miles driven is a bit harder. Some schools have required that all students, faculty and staff requesting a parking permit fill out a questionnaire to provide this data, i.e. round trip commute mileage, number of trips per week, etc. Other schools have used existing parking hang tag databases which contain home or campus address information and extrapolated from that – subtracting out the savings associated with those with parking passes who occasionally carpool, bike, take public transit or walk. Depending on your methodology for calculating the carbon footprint of commuting, it may or may not capture the emissions reductions that occur as a result of transportation strategies you implement to reduce driving and fuel use.

For air travel, your data collection goal is total passenger air miles paid for by or through your institution. Getting to this number may be difficult, depending on how travel information is collected and archived by your school. In addition to carbon dioxide emissions associated with burning jet fuel, the climate impact of air travel is a function of upper atmosphere emissions of nitrogen oxides and other factors. The Clean Air-Cool Planet Campus Carbon Calculator (discussed in the next section) incorporates a radiative forcing factor of 2.8 to account for this additional impact.

4.1.2 Data Collection for Campus Forest Offsets

Please see "A Recommendation on How to Account for Carbon Sinks in Campus Forests or Lands" by Jenn Andrews and the the "Campus Forest and Lands as Carbon Offsets?" section of this guide for a discussion of the tricky business of counting campus forest preservation as an offset to your campus carbon footprint.

4.2 Clean Air-Cool Planet GHG Inventory Tool

A number of GHG inventory tools are available. The ACUPCC participants agree to use one compliant with the Greenhouse Gas Protocol – a standard procedure for analyzing GHG emissions created by the World Resources Institute and the World Business Council for Sustainable Development.

Clean Air-Cool Planet’s “Campus Carbon Calculator” (available for free download) is compliant with this protocol and is the inventory tool most commonly used by campuses. Essentially, it is an elaborate Excel spreadsheet. You plug in the required data and it calculates total GHG emissions and the subsets of GHG emissions associated with various categories of input data.

The CA-CP Campus Carbon Calculator also makes analysis of your carbon footprint easy by providing a variety of ways of presenting, comparing, and trending the results. Each version of this excellent tool becomes more sophisticated and helpful. The Calculator will generate emissions trajectory graphs and allow you to normalize GHG emissions data in relation to various institutional statistics (see the the "Relative Measures of Progress" section of this manual for discussion of normalized GHG data).

Version 6 of the Campus Carbon Calculator has a solutions module with a number of interesting features. It will allow users to analyze and compare specific projects once project data is entered (see the "Carbon Reduction Efficacy" section of this manual for $/MTCO2e comparison of projects) -- thus ranking carbon-reducing projects according to their relative cost-effectiveness. This version can also calculate electricity line losses as well as production-related emissions for various grades of office paper. The latter may help you make the case for buying only 100% post-consumer content recycled paper. A future generation of the Calculator is expected to include a tool for calculating the carbon footprint and other environmental impacts associated with campus dining services.

For links to a number of completed campus GHG inventories, see the ACUPCC's online reporting system.

4.3 Your Carbon Footprint and Trajectory – What to Expect

While your GHG emissions inventory can quantify your carbon footprint and its major elements, it may not produce any real “Ah-hah’s!” The major sources of your carbon footprint should already be obvious. Typically, they are:

  • Electricity use (purchased or self-generated)
  • On-site fossil fuel burning for space and water heating and cooling
  • Commuting by students, faculty and staff

Your own GHG emissions inventory will likely confirm this. Putting some numbers to it can help, especially for those who don’t believe something is real unless it can be quantified.

When multiple years are analyzed, a GHG emissions inventory will show if emissions are holding steady, rising or declining over time. After some analysis, you might conclude that a trajectory of decreasing emissions over time can be explained by a successful energy conservation program or that an upward emissions trajectory can be explained by new construction, additional students, or more research activity. If you anticipate future campus growth, you could extrapolate from your recent trajectory and show that anticipated growth as an upward-pointing baseline from which you hope to deviate downward as a result of campus GHG emissions reduction efforts. Generally, your carbon footprint and trajectory will track energy use.

Your GHG emissions inventory may show you in graphic terms that your emissions are inching up each year for no apparent reason! In energy terms, this is often called “load creep.” An unaccounted-for upward creep in energy use and GHG emissions might be due to increasing computerization of your campus or a great number of small unidentified developments that collectively add up to incrementally greater energy use and thus more GHG emissions.

Obviously, if your school’s GHG emissions are on an upward trajectory for whatever reason, reaching aggressive campus climate goals is likely to be more difficult. As you identify measures and projects that can produce annual GHG emissions reductions, your CAP will need to subtract those anticipated reductions from an upward trending line – yielding less net reduction of GHG emissions than would occur if your trajectory were flat or already downward.

A GHG emissions inventory is helpful but it is not a silver bullet. It won’t for example, tell you what emissions mitigation opportunities exist in various buildings. An energy analysis of those buildings is required for that.

4.4 Who Should Conduct Your Inventory?

Who should perform your GHG inventory? If you haven’t done a GHG inventory before, you might assume it is very complicated and that you need to hire a consultant to do it. But while it takes time, inventory tools like CA-CP’s carbon calculator make doing a GHG inventory relatively easy. You may find that the hardest part is just gathering the needed data from various campus offices and departments.

Thus, a GHG inventory can be done in-house. It could be assigned to an energy manager, facilities engineer, or a sustainability coordinator. Students and faculty could also be recruited to help conduct your GHG inventory. In that way the inventory becomes a broader learning experience. While conducting the inventory itself does not represent a full semester’s work, an academic course could be created around the inventory by asking students to also unpack and study the “guts” of the inventory tool (examining its assumptions, learning how the spreadsheet works, etc.), develop campus GHG emissions mitigation strategies, create a simple CAP, and study the problem of climate change generally.

When gathering data for your first inventory, it makes sense to set up systems with the parties involved so that the same data can be more easily collected in future years.

4.5 Rolling Out Your GHG Inventory

The completion of your GHG inventory presents an important opportunity to raise awareness about your school’s impact on climate change and about the CAP process you have begun. For this reason, it makes sense to roll out your inventory with as much fanfare as possible. Your CAP team can brainstorm the most effective ways of doing this. It will help if the inventory is incorporated into a report about the need to reduce campus GHG emissions with examples of what your school is already doing and might do in the future.

Some outreach possibilities for releasing the inventory include:

  • Call a press conference
  • Write or arrange articles in campus and community publications
  • Hold “town” meetings to discuss
  • Give classroom talks
  • Ask drama students to do street theatre about your newly quantified carbon footprint
  • Ask art students to depict graphically
  • Encourage the campus student environmental club to dramatize with giant black chalk footprints around campus
  • Address prominently on your campus sustainability website and invite comments and dialogue

4.6 How Much GHG Number-Crunching Should You Do?

The increasing sophistication of GHG inventory tools comes at a price. After a point, more information and detail about your carbon footprint may not help you undertake the really important task of reducing those emissions. There are only so many hours in the day to do this important work and energy and sustainability staff are already stretched thin and over-worked. Thus, it is critically important not to get sidetracked over-analyzing your carbon emissions and, as a result, not have enough staff time to implement mitigation measures and projects. For example, should you refine your GHG inventory to the point where you know the carbon footprint of each campus building? Probably not unless you are sure that having those numbers will actually help you modify building energy systems and human behavior in campus buildings to produce additional energy and GHG savings worth more than the time and cost involved in completing that level of analysis.

When it comes to number-crunching, you need to be selective. What types of analysis will really advance your program? Consider what can be done with a handheld calculator. Suppose your campus’ carbon footprint was 100,000 MTCO2e/yr and you have 20,000 students. Simple arithmetic tells you that on a per student basis your school’s emissions are 5 tons of CO2 per year. Since burning a pound of coal releases 3.667 pounds of CO2, the average student is “responsible” for campus GHG emissions equal to burning 2,727 pounds of coal! Your CAP team could create a great motivational visual by dumping that much coal in front of the student union to dramatize each student’s impact.

4.7 How Geography or Your Power Provider Can Affect Your Carbon Footprint

Campus GHG inventories reveal that the geographical location of your school can make a big difference. Consider a college or university in a region of the country where most of the electricity is generated by burning coal. Each kilowatt hour of purchased electricity from that coal-intensive electric grid “contains” or is responsible for a much greater release of carbon dioxide than a kilowatt hour purchased by a school that receives power from a grid dominated by “lower carbon” natural gas generation or “zero carbon” hydro-electric or nuclear power. These regional differences in GHG emissions-intensity are captured by GHG inventory tools because they use CO2/kWh conversion factors based on the mix of electricity generation methods which exist in each region of the country.

It could be argued that colleges and universities in coal states like Ohio shouldn’t be “penalized” and forced to deal with much larger carbon footprints simply because they are in a part of the country where power is mostly generated by coal. However, this approach is reasonable and fair because there are real differences in the climate change impact of buying and consuming electricity in different parts of the country. Campuses in states with carbon intensive electricity generation will likely want to prioritize conserving grid-sourced electricity since each kilowatt hour they save will yield disproportionate carbon reductions.

A similar phenomenon can occur in electric markets where colleges and universities can buy power from private third party power producers (and use their local electric utility’s distribution system to deliver the power). The graph immediately below from the UC Berkeley shows what happened when in 1998 the university began buying its electricity from Arizona Public Services (APS). That moved caused the GHG emissions from UC Berkeley’s purchased electricity to more than double because of APS’ 38% reliance on coal. In 2006 Berkeley’s GHG emissions from purchased electricity dropped precipitously when the university resumed purchasing its electricity from Pacific Gas & Electric whose generation mix is 1% coal, 42% natural gas, 12% nuclear, 20% hydro, and 12% renewable.

Reprinted from UC Berkeley Climate Action Partnership Feasibility Study 2006- 2007 with permission of UC Berkeley.

Niles Barnes

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