Energy Use on Campus

Buildings consume a lot of energy, most of which powers mechanical equipment, lighting, and plug loads. Producing and delivering this energy has associated carbon and water impacts; thus my footpring associated with living in the dorms on campus will likely be a significant portion of my environmental footprint. This post is dedicated to quantifying the environmental impacts from living at Rice University.

However, my electricity usage is not individually metered, and I don’t pay utility bills. While I have an energy meter on the power strip that supplies most of devices (computer, phone charging, desk lamp, etc.), this represents only a fraction of my total consumption. To estimate my energy consumption on campus, a Rice sustainability professor offered numbers on the actual amount of electricity and natural gas consumed on campus in 2016. I used this data, the number of students living on campus, and estimations of the water and carbon footprints for various energy sources to estimate my footprint.

Step 1: Calculating consumption per on-campus student at Rice

To calculate how much energy each student living on the Rice campus consumes per school year, on average, I began with the total amount of energy (electricity and natural gas) purchased by Rice University in 2016. I used a series of estimates to calculate the average student consumption per academic year, as indicated below:

  • Total student consumption during academic year =
    (2016 total consumption) x (% used in dormitories and cafeterias) x (approx. % during school year)
  • Average student consumption = (Total student consumption during academic year) / (no. beds)
  • My spring 2017 consumption = 0.5 x (Average student consumption)

Step 2: Calculating carbon and water impacts of energy use

I used lifecycle CO2eq estimates for each power source from IPCC to calculate a weighted average carbon footprint for ERCOT electricity: 0.47 kg CO2eq/kWh. From last week’s investigation into water footprint calculators, I calculated a similar weighted average for the water footprint for ERCOT electricity: 0.29 gal/kWh. Most of the electricity Rice purchases comes from the general ERCOT grid, so I used these impact factors to assess this portion of my footprint.

Note that a small amount of electricity at Rice is purchased specifically from renewable sources (solar and wind), and I used impact factors associated with solar energy for this percentage: 0.045 kg CO2eq/kWh and 0.004 gal water/kWh.

Step 3: Calculating my impact

From my estimated spring 2017 electricity and natural gas consumption and approximate carbon and water footprints for various energy sources, I calculated my total carbon and water footprints from energy consumption in the dorms, January through May 2017:

  • Carbon: 1,094 kg
  • Water: 684 gal

I will use this total estimate as a starting point to estimate this portion of my footprint. From here, I will delve deeper into what activities contribute to this footprint, including HVAC, plug loads, and lighting.

A Review of Existing Water Footprint Calculators

I have several different parts of this project running simultaneously; while I’m compiling all of the information from the dance competition, I want to introduce a second major component of this environmental footprint analysis: water consumption. I aim to analyze the water I consume directly in my home and activities, as well as water consumed indirectly to produce goods and services to quantify my total water footprint for 2017.

Similar to my approach to my carbon footprint, I’m starting by researching the tools already available, namely online water footprint calculators. Generally, these water footprint calculators incorporate water used directly in the home, as well as secondary water uses for food production, transportation and energy, purchased goods, etc. Compared to carbon footprint calculators, these are much easier to use as a college student because they focus on consumption activities (e.g. how many times per day do you flush a toilet? How much beef do you eat per week?) rather than consumption via utility bills. I used three water calculators to calculate my footprint while living in the Rice University dorms, and the results (average gallons of water per day used) are given below:

I also estimated my own water footprint based on a literature review and measurements around my dorm room, deriving a total of 73.8 gal/day. You can find all of my calculations summarized in this document.

Much like the carbon footprint calculators, these results are extremely varied. The first two calculators (GRACE Foundation and National Geographic) considered the widest range of factors and asked for the most specific inputs, and from my perspective, their relatively close results boosts their credibility. In contrast, the Water Footprint Network used my gross yearly income to estimate a large portion of my footprint (which seems largely inaccurate due to an inevitably large number of assumptions), and my own calculations neglected several material production calculations, like the water consumed to produce my clothing. Thus, my intuition suggests that the correct number is in the 1,200 gal/day range, and we’ll see how this number progresses with my calculations over the course of the year.