Integrating HVAC into commercial CO2 (R744)-based refrigeration systems helps improve COP and energy consumption, even in warmer climates, according to Sergio Bridda, Refrigeration Systems Sales Expert at Eliwell, an Italian controls manufacturer owned by Schneider Electric.

Integrated CO2 systems also reduce maintenance costs and equipment footprint, he added.

Designed to optimize the performance of integrated HVAC&R systems, Eliwell’s DOMINO controllers cover the entire system, offering “flexible control solutions” for consolidated technologies, he said.

For example, the company’s DOMINO Zero controller features algorithms specifically designed for integrated CO2-based HVAC&R systems. DOMINO controllers are installed in 1,500 transcritical CO2 systems in Europe, the Middle East and Asia, Bridda said.

Bridda delivered his remarks during his presentation in an HVAC and heat pump session at the ATMOsphere (ATMO) Europe Summit on natural refrigerants. The conference took place November 15–16 in Brussels and was organized by ATMOsphere, publisher of

Reduced energy consumption

According to a 2019 case study from Eliwell, integrated HVAC&R systems can have a lower investment cost, higher COP and reduced maintenance costs compared to traditional setups that have separate systems for refrigeration and HVAC.

In this example, the supermarket’s traditional approach cost around €180,000 (US$192,000) for refrigeration, cooling and heating in terms of capital expenditure and installation, whereas the integrated system cost €140,000 (US$149,000).

The integrated system had a COP that was 28% higher than the previous systems and resulted in a 26% higher cooling capacity and a 1.5% reduction in energy consumption.

In a second case study presented by Bridda, integrating different HVAC&R elements into one centralized system resulted in a 70% reduction in energy consumption at a 3,000m2 (32,300ft2) commercial property in Sweden.

The building, which houses offices, shops, a restaurant and a gym, previously required 221MWh for district heating and 13.5MWh of electricity for its cooling needs. However, after installing a reversible CO2 heat pump, the building’s energy requirements reduced to just 71.1MWh for both heating and cooling.

For this project, Eliwell worked with Milan Polytechnic to develop an algorithm that would deliver the best COP based on the end users’ needs.

According to Bridda, there is a clear movement towards integrated systems both within commercial and industrial applications.

“CO2 is a sustainable solution that improves system operational efficiency,” said Bridda. “These case studies clearly show that CO2 supports the global goals for sustainability, both in Europe and around the world.”

“CO2 is a sustainable solution that improves system operational efficiency. These case studies clearly show that CO2 supports the global goals for sustainability, both in Europe and around the world.”

Sergio Bridda, Eliwell

While the adoption of R744 has grown, knowledge still needs to be improved, and Eliwell is committed to supporting CO2 applications, he added.

“Keeping solutions simple will help to grow the number of applications,” Bridda said.

Standardized controller

To overcome supply chain issues and rising inflation, Eliwell believes standardization and simplicity are important.

The concept of “less is more” is key to Eliwell’s DOMINO CO2 controllers, which were introduced in 2016 and aim to “maximize results without adding elements,” explained Bridda.

“In a time where we [frequently] deal with raw material shortages, price increases [and] delivery delays, we are proposing a sustainable, standardized solution with a reduced number of elements,” Bridda said.

Eliwell’s DOMINO controllers were developed in partnership with the University of Udine in northern Italy.

The products, which are typically used in food retail, include one element for the compressor rack or heat pump and a second element for the evaporators and extra exchangers, he explained, adding that the product is compatible with devices and electronics from multiple brands.

DOMINO Zero takes efficiency goals one step further, with an aim of helping end users achieve “zero waste in consumption and maintenance” for their transcritical CO2 refrigeration systems.