Share link


Leadership in Sustainable Design - Refrigeration Systems

Jason Christoff, PE, LEED AP BD+C

June 6, 2018

ms consultants continues its commitment to more sustainable design practices. One aspect is the design of retail food stores equipped with advanced refrigeration technologies. Advanced refrigeration technologies are an improvement from the traditional methods used and lead to lower energy use and costs.


Stores designed with these technologies have achieved Platinum certification from the U.S. Environmental Protection Agency’s GreenChill program, and have been recognized by the program’s "Best of the Best" award in 2017. The Best of the Best award recognizes the best Green Chill-certified store among all stores certified in the previous year.


GreenChill is a program designed by the U.S. Environmental Protection Agency (U.S. EPA) to promote and recognize environmentally-friendly, advanced refrigeration design and installation throughout the United States.  The certification is good for one calendar year, and the program is applicable for both newly constructed and renovated retail food stores. 


Without getting overly technical, to qualify for certification, designs must only use refrigerants with zero ozone depleting potential (ODP). The design guidelines also dictate how efficient the refrigeration systems must be, which is measured in pounds of refrigerant per total heat load. In addition, the refrigeration system installation must be tested for leaks to limit total environmental emissions from lost refrigerant over time. The ongoing maintenance of these systems is key, which is why stores must be annually re-certified. Certification levels include Silver, Gold, and Platinum designations.


There are many options for refrigerants with zero ODP, however, not all of these also have low Global Warming Potential (GWP). ODP and GWP are the two major units of measure to determine the overall environmental impact of a refrigerant, and both are referenced within the GreenChill program. Common hydro-fluorocarbon (HFC) refrigerants like R-404A or R-410A still have relatively high global warming potential in comparison to natural refrigerants like propane, ammonia, and carbon dioxide (CO2). With each choice, there are trade-offs in cost, operating and maintenance expenses, operational hazards, and sustainability benefits, so it is important to look at both the benefits and detriments of each refrigerant type.


In each certified project, ms consultants used supercritical carbon dioxide (ssCO2) based refrigeration systems. Carbon dioxide is a great refrigerant option as it is both inexpensive and has a high safety rating because it is non-toxic and non-flammable.


Additionally, because of its material properties, much less volume of CO2 is required to provide the same cooling effect as HFC refrigerants. However, ssCO2 based systems operate at much higher pressures (1600-2500 PSI versus 400-650 PSI), which means specialized equipment and components must be used.  Also, at these high pressures, additional safe guards must be employed—for safe pressure relief and detection and alarm systems—which add complexity and cost to the system. 


Regardless of the initial, relatively high upfront costs of CO2 systems, operating costs are substantially lower as CO2 is about 90% cheaper than more traditional HFC refrigerants.


Ready to learn more about GreenChill and advanced refrigeration technologies? Contact Jason Christoff at to learn more.


ms is also your partner in sustainability. Check out more sustainable design expertise here.