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SmartWay Technology Package Savings Calculator Explanation of Assumptions
This page explains the technologies and assumptions used in the SmartWay Technology Package Savings Calculator. The calculator is also available as a downloadable spreadsheet. (MS-Excel, 31K)
Definitions, Assumptions, and Manual Calculations:
General Assumptions:
Class 8 trucks are defined as vehicles with manufactures gross vehicle weight > 33,001 pounds.
Abbreviations:
Cost of Fuel = ($/gal)
Gallons Saved per hour = gal/hr
Gallons Saved per year = gal/yr
Hours = hrs
Year = yr
A direct fired heater is a small, lightweight, and efficient diesel fuel-fired device mounted in the cab of a truck. The direct fired heater provides
heat for driver comfort in the cab. This technology does not include any air conditioning capabilities.
Sample Calculation of Cost Savings
Annual Savings = Fuel Cost ($/gal) * Annual Idling (hrs) * Fuel Savings (gal/hr)
Fuel Cost = $4.00/gal
Annual Idling = 800 hours
Fuel consumption for typical truck at low idle** = 0.82 gal/hr
Fuel consumption for direct fire heater = 0.04 gal/hr
Fuel Savings for truck using direct fire heater** = 0.78 gal/hr
Annual Savings = $4.00 * 800 hrs * 0.78 gal/hr = $2,496 per year savings
** Trucks at high idle can consume more than a gallon per hour
An auxiliary power unit is a small diesel fuel-powered generator mounted outside the cab that provides the operator heat,
air-conditioning, and electrical power to run in cab appliances.
Sample Calculation of Cost Savings
Annual Savings = Fuel Cost ($/gal) * Annual Idling (hrs) * Fuel Savings (gal/hr)
Fuel Cost = $4.00/gal
Annual Idling = 2400 hours
Fuel consumption for typical truck at low idle** = 0.82 gal/hr
Fuel consumption for direct fire heater = 0.22 gal/hr
Fuel Savings for truck using an auxiliary power unit (APU)** = 0.6 gal/hr
Annual Savings = $4.00 * 2400 hrs * 0.6 gal/hr = $5,760 per year savings
** Trucks at high idle can consume more than a gallon per hour
Single wide tires or super single tires replace traditional dual tires with one single-wide tire and aluminum
wheel. This technology can be applied to all tractor and trailer tire positions except for
the steer tires. This technology saves fuel by reducing the weight
and rolling resistance of the tires and wheels, thereby reducing load on the engine. There is a slight aerodynamic benefit to this
technology as well. The benefits associated with this technology assume single wide tires on all applicable
axles of both the tractor and the trailer.
Sample Calculation of Cost Savings
Annual Savings = Fuel Cost ($/gal) * Annual fuel consumption (gal/yr) * Fuel Savings (%)
Fuel Cost = $4.00/gal
Annual Fuel Consumption = 18,000 gal/yr
Fuel Savings for truck using single wide tires** = 4%
Annual Savings = $4.00 * 18,000 * .04 = $2,880 per year savings
** In the event that someone would also want to purchase an aerodynamics package,
the combined efficiency would lead to an 8% fuel economy benefit.
Aerodynamics reduce drag which in turn reduces engine load. Fairings can be added to the
front, underside, and rear of the trailer to reduce drag. Benefits associated with trailer
aerodynamics assume that the tractor pulling the trailer also has an aerodynamic package
installed on it.
Sample Calculation of Cost Savings
Annual Savings = Fuel Cost ($/gal) * Annual fuel consumption (gal/yr) * Fuel Savings (%)
Fuel Cost = $4.00/gal
Annual Fuel Consumption = 18,000 gal/yr
Fuel Savings for truck using trailer aerodynamics** = 5%
Annual Savings = $4.00 * 18,000 * .05 = $3,600 per year savings
** In the event that someone would also want to purchase an single wide tires,
the combined efficiency would lead to an 8% fuel economy benefit.
Under inflated tires can cause significant losses in fuel efficiency,
plus dangerous blow outs. Automatic tire inflation systems can ensure the
safety of drivers while lowering fuel costs.
Sample Calculation of Cost Savings
Annual Savings = Fuel Cost ($/gal) * Annual fuel consumption (gal/yr) * Fuel Savings (%)
Fuel Cost = $4.00/gal
Annual Fuel Consumption = 18,000 gal/yr
Fuel Savings for truck using automatic tire inflation = .6%
Annual Savings = $4.00 * 18,000 * .006 = $432 per year savings
A diesel oxidation catalyst is a device added to the tractor's exhaust system to reduce
emissions of particulate matter and other pollutants. Diesel oxidation catalysts have no impact
on fuel economy. There is no calculation for this technology since it neither consumes nor saves
fuel.
Loans are calculated by multiplying the cost of the technology package by the payment
function.
The payment function is:
The interest rate divided by 12 months to get the periodic interest rate.
The periodic interest rate is then placed into the payment function.
The payment function is calculated as the total cost of all the selected
technologies multiplied by the quotient of periodic interest rate multiplied
by the periodic interest rate plus one, to the combined power of twelve times
the number of years that loan is for (the number of loan periods); then divided by the periodic interest rate multiplied
by the periodic interest rate plus one, to the combined power of twelve times
the number of years that loan is for and then subtracted by one. An Example:
|
If the: Cost of technology package = $1000 Periodic interest rate = 0.0041667% (5% (.05) divided by 12) Loan periods = 48 (12 months multiplied by 4 years) The equation will look like this: $1000 * (0.0041667 * ((1+0.0041667) to the power of 48)/(((1+0.0041667) to the power of 48) -1)); The monthly loan payments for the above $1000 loan would be: $23.03 |
Disclaimer:
The costs and benefits described in this calculator are estimates only, based on national averages and other sources for Class 8 Trucks. Actual fuel savings may vary, and will depend on a variety of factors, including load, equipment type, driver performance, distances traveled, vehicle speed, etc.
Assumptions for idling control devices assume that the devices are being used while the tractor's engine is off. Assumptions for Single Wide Tires consider use of this technology for both the tractor and the trailer, except front steering axles. Assumptions for Trailer Aerodynamics assume that the tractor already has an aerodynamic profile. Please note that some of the links and checkboxes associated with these pages use popup windows to provide and gather information more efficiently.
Please contact us to let us know what you think about the calculator and/or to suggest improvements.