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Modular Central Plants for Refrigeration

March 4, 2021

Apart from the pandemic, the HVACR industry is again at an inflection point in equipment design as a result of refrigerant environmental concerns

In February of this year, the major stock market indices were at all-time highs, the U.S. non-residential construction market was up over 14 percent from the prior year, and outlook for the year was favorable on most fronts. By the end of March, as a result of the COVID-19 pandemic, the construction industry had slammed on the brakes, and projects across North American halted.

The implications of this slowdown are noteworthy—particularly when it comes to central plants. While demand still exists for much of the market, the delivery system needs to be re-evaluated. With time to pause and rethink how we deliver new central plants in a pandemic—not to mention the world of changing refrigerant regulation — many project owners are considering the alternative of modular, off-site construction.

Modular Central Plants’ (MCPs) growing popularity is attributable to the inherent cost, schedule, expandability and flexibility benefits they provide for customers who require central chiller and boiler utility plants. Those same benefits make them an ideal solution for today’s challenges and solving for both the urgency brought by of COVID-19 and the impending refrigerant regulation. They are, in fact, the best choice for the future of central plants. 

In the current state of the COVID-19 pandemic, construction project management has become significantly more challenging. Project schedules are in flux as each state, province and local government evaluates and acts on the best response to safety concerns. Modular central plants are built offsite, in a safe and controlled environment, representing a real solution to jobsite scheduling and safety concerns for construction managers. The entire central plant arrives as a piece of equipment, minimizing on-site labor for reassembly, and virtually eliminating the scheduling challenges of maintaining proper social distancing on the jobsite.

Servicing central plant equipment during a pandemic has also created some real challenges. Safety concerns can lead to restricted visitor access to the facility. MCPs offer security to the building proper by the physical separation between the plant and the main building. Service personnel may have restricted access to the main building, but still may be allowed access to the central plant. The complex maintenance procedures in the heating and cooling system are thus separated from the main building and can be carried out by professional service organizations without the risk of coming into contact with employees or tenants.

Apart from the pandemic, the HVAC industry is again at an inflection point in equipment design as a result of refrigerant environmental concerns. The search for refrigerants that offer zero ozone depletion potential and very low global warming potential (GWP) presents some challenging choices for building owners and designers in equipment and mechanical room design. Decisions regarding efficiency, safety, mechanical room space requirements, and future expansion may become more challenging with design impacts of the new refrigerants. Many of these challenges are be addressed by MCPs.

One potential direction for future low GWP refrigerants is the low-pressure refrigerant R-1233zd.

One potential direction for future low GWP refrigerants is the low-pressure refrigerant R-1233zd. This choice offers safety and efficiency, but at the premium of larger mechanical equipment space requirements. Due to the nature of the low-pressure gas, the chiller equipment is inherently larger than medium pressure machines. This presents challenges for optimizing value-generating floor space and planned expansions. The MCP solution provides the most space-conscious designs, regardless of the equipment size, and the equipment room may be external to the main building.  The design premise of MCPs takes into account future expansion plans, allowing additional mechanical space to be added as needed in the future without compromising the value-generating space in the building.

For medium and higher-pressure machines, A2L refrigerants (as classified by ASHRAE Standard 34-2019), including R-32 and R-1234ze, offer efficiency and cost points that make them highly desirable. These refrigerants are already in use throughout the world, and U.S. model building codes are being updated to include correct design for incorporating new 2L gasses. ASHRAE Standard 15-2019 includes provisions for 2L refrigerants, which will dictate changes in mechanical room construction and safety. By housing the central plant outside the building, MCPs offset any concerns with the mild flammability of 2L gasses. Further, because MCPs are governed by the latest edition of the UL 1995 or UL 2-40 safety standard for equipment, they actually fall outside of the local model building codes, making MCPs a great choice given this uncertainty. The UL equipment safety standard is updated universally, and on a stricter schedule than local building codes, meaning that the new refrigerant gasses may be used in an MCP potentially much sooner than in the construction process.

It’s no surprise that MCP sales are thriving in today’s market. MCPs’ traditional benefits — including fast tracking projects with tight construction schedules, reducing installed-cost-per-ton, and transcending spatial constraints—are reimagined in today's world.  When safety, efficiency and future expansion are paramount, MCP is the answer.