Additional Idle Solutions

The report identified technologies that fleets can use to reduce engine idling:

  • Automatic engine start/stop start systems
  • Battery HVAC systems
  • Diesel APUs
  • Fuel-Operated/Diesel-Fired Heaters

However there are number of ancillary technologies that can be beneficial to a fleet’s idle-reduction efforts. Most of these sleeper tractor additions are passive, and can be used in conjunction with other active idle-reduction systems, to achieve even better levels of idle reduction.

They include:

  • Additional cab insulation decreases the energy demanded by the heating and cooling systems. Insulated bunk curtains, windshield curtains, and extra insulation are options.
  • Light-colored paint helps reduce the heat loading of the sun on interior of the vehicle. A black vehicle requires 26.3% more energy to cool on a sunny summer day than the same baseline vehicle painted white.
  • Auxiliary CPAP battery powers a CPAP machine through the night, which can help relieve the truck’s batteries from having to power the machine.
  • Ultracapacitor starting system can alleviate the strain on discharged batteries and help start the engine. The system can store energy and deliver power.
  • Sleeping quarters, such as hotels or dormitories, may be the most radical method of reducing idling by getting the driver out of the vehicle altogether for the HOS restart period.
  • Truck Stop Electrification is similar to hookups at RV parks and allows trucks to power everything drivers need from an external power source. Some systems require special wiring and equipment. Others provide everything through a console that fits through the window frame.
  • Off-board AC power systems (also known as shore power) combine elements of both vehicle and truck stop electrification as they require both AC wiring and power ports to be installed inside the sleeper as well as infrastructure to be deployed for an external AC power source.
  • Solar panels can augment the amount of power generated by the alternator, but they are especially useful for charging the battery HVAC system to allow longer running time. And to help prevent hotel loads from draining the batteries.

Fleet Survey Results

  • If a fleet does not use APUs, their idle percent tends to be in the 30% to 50% range
  • If a fleet uses APUs, idle percent is in the single digits to 20%
  • Fleets seem to be split on diesel APUs vs. battery HVAC systems with some fleets using both (but not on a single vehicle)
  • Use of auto start-stop systems is increasing
  • Almost everyone uses diesel fired heaters
  • Most fleets are looking for positive ROI, but most of them also think there is significant value in driver retention and hiring

Decision-Making Tools

Our team produced top-line tools to assist fleets in making their idle-reduction technology choice:

  • The confidence matrix summarizes the study findings and indicates NACFE’s confidence in the various idle-reduction technology solutions.
  • The Payback Calculator allows fleets to estimate the payback in months for various idle-technology solutions. Fleets input data into the form and the calculator uses the data along with the information gathered by the study team to quantify and benefits and consequences likely to be experienced by the fleet in terms of upfront costs and year-over-year costs.

In addition the report contains challenges and changes charts for each of the anchor technologies. The charts can be found in section 9 of the report.



As a result of research and interviews the study team reached the following conclusions concerning idle reduction in the sleeper cab market:

  1. Reducing idle is good for the environment, saves fuel and improves a fleet’s “green image.
  2. A 10% reduction in annualized idle percentage is worth about 1% in fuel economy that results in a $500 to $700 annual savings assuming 100,000 miles a year and diesel at $3 a gallon.
  3. Driver hiring, comfort and retention are mentioned in almost every conversation about idle-reduction technologies. Some have said that offering a good solution is a requirement for hiring and retaining drivers.
  4. There is no “one size fits all” solution to idle reduction.
  5. Drivers are still a very important part (If not the most important part) of successful management of idle times.
  6. Depending on “shore power” (outside electrical connection) to be available is not a reasonable idle-reduction solution for most fleets as the number of electrified parking spaces is extremely small compared to the number of trucks that need to be parked at any given time.
  7. Most suppliers of idle-reduction technologies mention that their solution helps minimize maintenance costs, particularly in the vehicle’s aftertreatment system. However, we have been unable to uncover any data that actually substantiates those claims.
  8. The answer to the question of the resale value of trucks equipped with idle-reduction technology is unclear.
  9. Maintenance of the vehicle’s battery connections and electrical systems is critical to getting the best performance out of idle-reduction technologies.