How are the results calculated?
Thermostat savings are based on the U.S. Department of Energy estimation that a residential heating bill can be reduced “as much as 1% for each degree if the setback period is eight hours long.”
For the purposes of this illustration, natural gas consumption, costs and NOX emissions were focused on the average Salt Lake County household in the month of January. It was also assumed that an average of 20% of annual household natural gas use in Salt Lake County occurs during the month of January.
Utah-specific data was obtained from:
- The Utah Division of Air Quality interactive data explorer: amount of NOX emissions due to residential natural gas heating (available by county).
- U.S. Energy Information Administration: overall residential natural gas consumption in Utah.
- Questar: residential price per DTH in January 2013 ($8.35).
- U.S. Census: number of housing units in Salt Lake County.
Carpool and transit savings are based on formulas used by Clear the Air Challenge:
“Dollars saved is calculated by $0.566 x the number of miles saved. Figures come from AAA Exchange at the cost per mile of 56.6 cents based on a mid-sized sedan and traveling 15,000 miles per year. This figure includes all costs of driving (costs of ownership, maintenance, gas, etc.)….
Figures from a 2008 American Bus Association Foundation study titled, Updated Comparison of Energy Use & CO2 Emissions From Different Transportation Modes were used for the emissions calculations. For public transit methods, the available options of “Light Rail” and “Transit Bus” are combined for an average of 254.5 g CO2 and other particulates per passenger, per mile. For private vehicle transportation, cars, SUVs, and motorcycles, the “Car – 1 Person” figure equates to 378 g CO2 and other particulates per passenger, per mile.”
Clear the Air Challenge also assumes that the average cost per mile of transit is $0.45. For the purposes of this illustration, the average length of a round-trip commute is assumed to be 20 miles.