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The Active Thermal Transport System (ATTS)

Cold-Chain logistics is a growing global market. Ability to get fresh and frozen products to market is key to the success of food transport company's bottom line. A major consider​ation when conducting cold-chain logistics is maintaining a fleet of refrigerated trucks and containers that meet the requirements of the customer. In both cases, this requirement is driven by some form of energy tradeoff and environmental consideration. SSI is partnered with Green World Tek , LLC and PhaseStor using BioPCM technology to bring an exceptional product to the road, sea, and intermodal "reefer container" market. Coupling PhaseStor's no-carbon footprint and environmentally safe material with Green World Tek's proprietary, patented distribution system provides a superior product that significantly reduces the cost of powering refrigeration unit compressors supporting cold-chain logistics. Below is a snapshot into the capabilities of the Active Thermal Transport System (ATTS).

Answer to Reducing Refrigerated Trailers Operating Costs

Trucking refrigerated box (“Reefer”) temperatures are maintained through improvements to the insulation of the box, the mass of the load, and the efficiency of the cooling system. Driving the cooling system is a generator which typically runs on diesel fuel.  Ability to reduce the generator run times while maintaining desired temperatures directly impact the cost for the Reefer operations.

The ATTS is designed to address all three factors that influence efficient reefer operations. The system provides additional insulation at the top of the reefer box, provides increased cold load mass through the BioPCM (N+1 redundancy), and reduces the fuel consumption of fuel for the generator.

The ATTS combines all three factors to reduce generator run times for set points of +35°F to +41°F by approximately 70%, significantly impacting cost to operate and maintain the systems all while achieving desired box temperatures. Colder temperatures (i.e., 14° F or less) are achieved with additional panels and/or lower set points.   

Result: Significant Reduction in Diesel Fuel Costs to Operate a Reefer

Test Case

(Average Outside Temperature) 

Testing/V​alidation: ​ Conducted with Multiple Carriers

Without ATTS: A long-haul, 53’ refrigerated carrier conducted a fuel consumption test on a compressor during a 49-hour cooler run transporting a 34K pound load. The set point was 34° F with average outside temperature of 57.5° F. The compressor was on 57.4% of the run.

With ATTS: The carrier conducted a fuel consumption test on the same reefer box and compressor during a 68-hour cooler run transporting a 36K pound load. The set point was 34° F with average outside temperature of 61° F. The compressor was on 0.086% of the run.

Installation of the ATTS resulted in an 85% reduction of compressor “on ti​me” consuming 85% less diesel fuel

Additional ATTS Field Test Data

(Outside Ambient Temperatures ranged between +46 and 88 Degrees Fahrenheit)

What is the ATTS?

A non-intrusive system of two layers of panels housing the environmentally friendly BioPCM® material installed on the refrigerated truck/container ceiling at a depth of 1.63” and in an area of 34’ x 6.7’ (80”).


A 53’ Reefer Box requires 136 panels housed in channels double stacked (additional panels can be included for greater BTUs thermal storage).


An install requires two people about one-half day for a 53’ box (install team can be company personnel or an SSI/GWT installation team).


The ATTS is adaptable to trailers outfitted with an air chute (center or corner).


Panels are secured without fasters eliminating any concerns for damage to leased reefer boxes.


Total weight for the ATTS on a 53’ trailer is 650 lbs.


Approximately 2,800 BTUs per row (8 panels) and 350 BTUs of thermal storage per panel equaling 47,600 BTUs (approx. 4 Ton) thermal storage on 53’ trailer (capable of additional rows increasing the thermal storage).


Easily modified to customer’s requirements.


System is transferrable to other refrigerated trailers when required.

ATTS Features

  • Maintain a setpoint temperature between negative 85° F and positive 347° F.
  • BioPCM® (Phase Change Material) is plant-based, environmentally safe, lightweight, non-flammable, no carbon footprint.
  • A passive system requiring no external energy source other than the initial cooling air charge provided by the cooling compressor and the transported load’s natural thermal storage.
  • Uses include cryogenically frozen, frozen, sub-zero, refrigerated, & cool.
  • Trailer-adaptable systems designed for a 53’ reefer produce a minimum of 47,600 BTU (approx. 4-ton) thermal storage.
  • Set Phase Change temp at 37.4° F for coolers/docks.
  • Set Phase Change temps at +5° F to -85° F for freezers.
  • Temperature stability/resilience / Thermal N+1 Redundancy (12 hours).
  • Compressor run-time/cycles shows significant reductions resulting in fewer maintenance hours and less fuel consumption.
  • Peak demand load shifting / enhanced / supplemental Fly-wheeling all positive factors improving cooling conditions.
  • Internal reefer temperature bandwidth swing reduced from industry standard of +/- 16° F to an average +/- 8° F. 
  • Maintains a useful operational life of 30 years. Transferrable to other trailers/containers.
  • Validated through Lemark Services Engineering and calculated using ASHRAE 2014 Handbook for Refrigeration systems.

ATTS Cost Savings

The below Example features the cost savings without and with the ATTS.  A conservative 50% reduction is used for the cooling compressor "on time" (testing shows average 71% reduction) and a standard compressor usage of 5400 hours per year at an average diesel fuel cost of $4.52 (2/2023)

With ATTS  (+5 C)

Compressor Reduction: Conservative 50%

Assume 5,400 hrs/yr. (18hr/day/300 days)

 ATTS modified Reefer operates 2,700 hrs/yr

2,700 hrs/yr. @ 0.85 gals/hr fuel consumption = 2,295 gals

2,295 gals @ $4.52/gal = $10,373 per year fuel cost

Without ATTS  (+5 C)

Compressor Reduction: 0%

Assume 5,400 hrs/yr. (18hr/day/300 days).  

No ATTS modification.

5,400 hrs/yr @ 0.85 gals/hr fuel consumption = 4,590 gals

4,590 gals @ $4.52/gal = $20,747 per year fuel cost

ATTS Cost Savings of $10,374 per year = 50%

*** Calculate YOUR REEFER's Cost Savings ***

When selecting the calculator below, it will bring up an excel spread sheet. Please select the dowload button at the top of the opened file which will download the calculator to your system. Then select enable editing to allow you to place your specific data in the calculator. The calculator will return to the example provided once you leave the site. 

Various kit sizes available.

Volume discounts providing additional cost savings and greater ROI available.

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