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.