A. U.S. Department of Energy 

laboratory managed by 

The University of Chicago

Economic Analysis of Commercial 

Idling Reduction Technologies

Which idling reduction system is most economical for truck owners? Linda Gaines and Danilo Santini – Center for Transportation Research

Argonne National Laboratory

System

Idling (baseline)

Heat recovery

Automatic start/stop

Cab/bunk heater

Evaporative cooler

Air conditioner

Auxiliary power unit 

(APU) or generator set

Electrified parking space 

(EPS) (single system)e

EPS (dual system)f

Cab Comfort Technologies

Services

All

Heating

All, intermittently

Heating (cab)

Cooling

Cooling

All

All

All

 Fuel Use

 (gal/hour)

 0.8

 Negligible

0.8 if on, 0 if off

 0.04

 0.015

 0.15

 0.2

 0

 0

Installed

Cost ($)

 0

 600

1200

1300

1800

 4000d

8000

 10

2500

Maintenance

($/yr)

See notea

 0

See noteb

 110c

100

 200c

400

 0

100

Charge

($/hr)

0

0

0

0

0

0

0

 2g

1

a

 Defaults for idling maintenance: $150/30,000 miles for oil change, $10,000 at 500,000 miles for overhaul.

b

 Same as idling, multiplied by the fraction of time the engine is on. Possible additional contribution from engine 

turning on repeatedly.

c

 American Transportation Research Institute, Idle Reduction Technology: Fleet Preferences Survey (February 2006)

d

 No battery replacement included for battery-powered air conditioner.

e

 A heating, cooling, and ventilation unit above each parking space is connected to a window-mounted service module 

via a flexible, reinforced, concentric hose that also delivers communications and entertainment packages.

f

 On-board equipment powered by extension cord to wayside electrical pedestal.

g

 $2.18 per hour retail; $1.85 per hour fleet discount. (Ref: Brass, Larisa: IdleAire's promise: New financing could help 

put a Knoxville company in truck stops across America, Knox News (February 20, 2006) (accessed June 2, 2006).)

Payback Time vs. Fuel Price, 

by Device, Used 2,000 Hours per Year

Total Cost for Six Years of Operation 

vs. Idling Time @ $3/gallon

40

35

30

25

20

15

10

5

0 500 1000

Hours per Year

$(1000)

1500 2000 2500

0

Idling

Heat recovery

Heater only

Heater plus air conditioner

APU

Dual system EPS

Single system EPS

3

4

5

6

7

8

10

2

1

1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

Diesel price ($/gallon)

Payback time (years)

0

9

a

Actual amount of time heater can be 

 used varies by location

Increasing 

level of cab 

comfort

Heater only (used 50% of year)a

Heater plus evaporative cooler

Heater plus air conditioner

APU

Top-of-line APU ($10,000)

Dual system EPS

Conclusions

1. Fuel-fired heaters are the least expensive means of providing 

heating for trucks that would otherwise idle overnight. The 

worksheet should be used to confirm whether an auxiliary 

air conditioning unit is also economical.

2. On-board IR systems (including dual-system EPS) are the 

least expensive means of providing full cab comfort 

services, in the event of high annual use hours and long 

retention of the systems (six years illustrated here).

3. For a low-annual-use case, a single-system EPS (an offboard system) is the least expensive full-service choice 

when fuel prices are high. 

Overview

Several factors have combined to create a surge of interest 

in idling reduction (IR). One is the increasing number of 

states and localities that have instituted restrictions on idling 

for trucks and other heavy vehicles. Extended idling by 

commercial trucks, both overnight and during the workday, 

also costs truck owners billions of dollars annually and uses 

a significant amount of our petroleum resources. Increased 

interest in IR has led to rapid growth in the number of 

equipment suppliers and the types of IR devices available. 

Although many suppliers have joined together to educate 

potential customers and government agencies, individual 

manufacturers often provide conflicting claims about the 

comparative financial merits of different devices. That makes 

it difficult for truck owners to choose the right equipment for 

their needs.

Note: Unknowns such as quality of service, IR device reliability, and variations in 

truck owner and driver preferences and in the need for services mean that the findings 

are informative, but not conclusive. Each option must be evaluated on its merits, as 

applicable to the owner's needs, before a purchase decision can be reached.

Approach

This effort considers the types of devices available and 

provides a worksheet that allows a truck owner to estimate 

the costs, savings, and payback for each system. The truck 

owner must supply several inputs (particularly idling profile) 

to determine what the payback period is for each device and 

what the cash flow looks like as a function of time for typical 

inputs. Although it was developed with trucks in mind, the 

worksheet could be used for buses and other types of heavy 

vehicles as well.

This figure shows how payback time 

varies with fuel price for a range of 

device costs (from $1,300 to $10,000) 

for a long-haul truck that idles for 2,000 

hours per year (40 h/week 50 weeks). 

At $3 per gallon for diesel fuel, devices 

costing $7,000 or less pay back their 

investment in the two-years-or-less 

timeframe that many truck owners have 

cited as a goal, and even devices costing 

$10,000 pay back in under three years. 

The same analysis can be performed for 

day cabs, but because these trucks idle 

fewer hours per day, only a much smaller 

investment will pay back in an acceptable 

period. Payback for the single-system 

electrified parking space (EPS) is 

immediate at fuel prices over $2.50 per 

gallon, but the figure below shows that 

other criteria are also important.

This figure compares total cost to the 

truck owner over six years for different 

IR systems, assuming the current diesel 

price of $3 per gallon. This graph shows 

that, for the technology options that 

supply both heating and cooling, the 

relative ranking changes as a function of 

hours of idling eliminated. It is also true 

that diesel fuel price and length of 

ownership can change these rankings. 

Expensive fuel and long vehicle 

ownership favor on-board options and 

the dual-system EPS. Also note that the 

heater and heat recovery options are 

only needed in winter, and heat recovery 

only has capacity for up to four hours 

per day.