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“We are very happy with the CO2 solution CIMCO proposed. It fits well with the school’s sustainability goals and positions us favorably for the next three decades or more”

- Ron Tola, Director of Major Projects, Princeton Day School



Sustainability Matters


Princeton Day School (PDS) has long been committed to the protection of environmental resources. The school considers sustainability, environmental education , and the modeling of ecological decision-making within the institution an essential aspect of its work. 


Leading by example, PDS decided it was time to upgrade the aging R22 refrigeration system serving its NHL-sized ice arena. With the changing regulatory landscape and subsequent rise in R22 refrigerant pricing, it was no longer feasible to maintain the system that was fast reaching its end-of-life as well.


Not to mention the environmental burden of running a system with a refrigerant nearly 2,000 times more potent than the climate-friendly CO2 alternative. (R22 has a global warming potential of 1,810 while CO2 as the benchmark is set at only 1.)


The school hired a consulting firm to do a feasibility study to get started. The firm reached out to CIMCO Refrigeration (CIMCO) to better understand CO2 as a solution and its related benefits. The firm then presented its study to the school after which PDS Director of Facility Operations Robert Clemens contacted CIMCO to work together on a CO2 design that would suit the school’s needs.


“Robert demonstrated exceptional leadership and expertise in developing the project,” said Brad Wilkins, US Recreation Project Team Lead at CIMCO Refrigeration. “He completed a detailed feasibility study and maintenance analysis, scheduled regular check-ins to prevent on-site delays, and established upfront lead times and schedules with CIMCO, minimizing potential risks. His request for a five-year maintenance proposal upfront ensured a strong partnership from the start.”


Clemens’ goal was to find an all-encompassing solution that would serve the school for the next 30 years without worrying about having to replace it prematurely. The CO2 option provided just that. Choosing a natural refrigerant removes the risk of having to prematurely replace the refrigeration system because of regulatory changes that affect the availability of fluorinated refrigerants.


“This seems to be a common discussion now – the uncertainty around the future of f-gasses. It doesn’t make sense to put in a system only to replace it in five to 10 years,” said Wilkins.


A Complete Solution


The CO2 system designed for PDS will include all the latest technological advancements to ensure optimum efficiency and alignment with the school’s sustainability goals. Not only will a new refrigeration CO2 Eco Chill system be installed, but also an adiabatic CO2 gas cooler, CIMCO Eco Chill heat exchangers for heat recovery, and a CIMCO Eco Dry unit for mechanical dehumidification.


The new refrigeration system will have a cooling capacity of 150TR (528 kW) of which around 100 TR (352 kW) will be used to maintain the ice rink and the additional 50 TR (176 TR) for the EcoDry on the dehumidification side. This system is expected to be at least 15% more efficient than the existing R22 system.


Part of the project will include replacing the existing gas dehumidifier, thus removing the arena’s need for natural gas to provide heating and dehumidification. Instead, a CIMCO Eco Chill designed unit will capture the heat from the refrigeration system to provide hot water for the Zamboni whilst also heating the glycol for underfloor snowmelt.


The Eco Chill repurposes the energy removed from the ice sheet during operation and applies it to wherever heating is needed within the building. Utilizing the heat recovery from the refrigeration system decreases the arena’s energy consumption and lowers greenhouse gas emissions (and of course, its related energy costs). This shift away from natural gas aligns strongly with the school’s sustainability goals.


A CIMCO EcoDry unit will be installed to provide all the makeup air for the arena and its dehumidification needs, using the heat recovered by the Eco Chill. This will be the first time an Eco Dry unit will be used with a CO2 system in the U.S. “CIMCO has many successful case studies for our EcoDry units, and we are excited to now try this proven technology with a transcritical CO2 refrigeration system as well,” said Wilkins.


The refrigeration system will also include adiabatic gas coolers that improve the efficiency of CO2 in all climates and negate the need for an evaporative condenser. This will lead to significant water savings (as minimal water is needed unlike with standard evaporative condensers or cooling towers) and completely remove the cost of water treatment.


To ensure the smooth running of the system, CIMCO will provide a five-year warranty on the packaged solution plus an extended five-year service agreement. This will give the school’s own staff five years to get familiar with the system and how to run it efficiently. Luckily CIMCO has several such technicians in close proximity to the school, offering peace of mind to the customer.


“We are very happy with the CO2 solution CIMCO proposed. It fits well with the school’s sustainability goals and positions us favorably for the next three decades or more” said Ron Tola, director of major projects at PDS.


The start-up of the upgraded ice arena is planned for August 2023.





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