http://energytrust.org/library/reports/eps_2008_pilot_report.pdf
My Carbon Footprint:
This discussion of carbon footprint is copied from a blog posting:
In effort to show the value of home energy conservation efforts, I have done math for heat transfer, and fuel costs crunched for my city. Now, I want to join the game of declaring benefits as reduction of carbon footprint. An advantage in this is that low, subsidized, cost of heating fuel is divided out. I accept numbers from a recent issue of National Geographic, March 2009, p 67:
Driving: a gallon of gasoline adds 19.6 lb CO2.
One KWh electric use adds 1.5 lb CO2.
100 cf of natural gas emits 12 lb CO2.
I need to back up a few steps, and understand where I am expected to go, with reduction employing such numbers. Start with the EPA Household Emissions Calculator.
Here is my annual carbon footprint, living alone, working hard as a weatherization contractor:
12,438 pounds CO2 in driving 13,400 miles per year.
2,808 pounds CO2 for 239 therms of natural gas in an efficient furnace heating my modest 1000 sf home and productive workplace.
7,063 pounds of CO2 to generate 7663 KWH of electricity per year.
22,309 pounds CO2 before savings efforts volunteered, about 1000 pounds of CO2, through car maintenance and through steadfast recycling.
Numbers correspond fairly well with the National Geographic conversions. I am near the 20,750 per-person US average. I have begun to share my home, and that will push me below the average. The sharing of my home is in fact the most powerful thing I can do.
Better-educated by this study, I am inspired to save a few thousand pounds of CO2 emissions per year. Here are several ways I could save 1000 pounds: Drive less by 8%, fifty gallons, or 1080 miles. Reduce electricity use by 14%. Reduce my use of natural gas for heating, by a harder-to-do 35%, or 85 therms. There is promise in all of these. Only heating reduction through conservation, what I do for others as a contractor, is painless.
I began this writing exercise upon concluding that large effort in a customer's attic of 720 sf, going from R13 to R40, would save only fifty therms per year, the equivalent of using thirty gallons in driving. It was a small gain, but beyond painless. It is a more than twenty percent annual return on the customer's investment, forever, and further value in more-comfortable living. The customer will still look for harder ways to reduce footprint.
My Energy Performance Score, EPS:
The EPS for my home is not some mystery known only to a mysteriously-trained professional through complex computer analysis. I can infer the hand-calculation methodology from a sample report by Earth Advantage Institute, for a one-story single family home of same vintage as mine.
My home's carbon emission is 2808/2000 = 1.4 tons CO2 per year, for natural gas consumption, and 7063/2000 = 3.5 tons CO2 per year for electricity consumption. Total for house: 4.9 tons CO2 per year. Comparison numbers of an EPS report are proportional to house heated area: At 1000 sf, Oregon Target is 5.2 tons CO2 per year, Oregon Average is10.4 tons CO2 per year.
My house has below-average energy use. That's all EPS tells me. There is really no "score." The usefulness of EPS is simply in a graphic presentation, first a scale of Energy Use, MBTU/ yr, and then a scale of Carbon Emissions, tons/ yr. The mystery is only in statement of target and average numbers for one's state or region, for the comparison. I am sure that mystery too, does not require a computer. I will like being able to keep my own score. I will be able to track a change like switching from an electric clothes dryer, to gas. I might sooner switch to "solar" drying, with tracking incentive, just doing math on my annual utility bills.
Scores will have a lifestyle variable, for comfort required. I keep my thermostat way down. If I needed a warm house, my carbon emission would rise.
Earth Advantage Institute is the best proponent of EPS, and advocates it to the nation. Yet, at the bottom of their report, I am referred for more information, to:www.EnergyPerformanceScore.org.
Try it.
It is simply the Energy Trust of Oregon home page.
My Involvement With An EPS Pilot Project:
The first two attachments are cited sample EPS presentations, in the two formats. They illustrate historic use of natural gas and electricity in a single-story rental home completed in 1951. The history includes indefinite condition of a detached warm air duct from a modern gas furnace, into the crawl space. I don't know if or how the data fit with the EPS Pilot Report linked at top of page. Beyond reattaching the duct, the house was left unimproved for more than a year. Then the house floor (crawl space) was insulated by another contractor, with the 80% effectiveness common with laced-up unfaced batts, staples and twine, not always well-placed, not often taut. I was inspired to do my very best with weatherizing the attic. Consequences of the improvements are studied in the third attachment. If the only purpose of the pilot program was to put out the report on historic data, and not to be part of energy-saving invention, then I guess the project is over-with. Over-with, where two sets of duct blaster and blower door tests were performed on the unimproved house, perhaps by PTCS prescription. If the measurements have any significance, and I doubt that they matter much for a house that can not be too tight, they should reflect the improved condition. I wonder how scores should inspire and monitor efficiency investments.