top of page
Search

Innovating in Sustainable Construction: Helping a Major Bay Area Tech Company Decarbonize

  • Writer: MAI Construction
    MAI Construction
  • Jul 6
  • 3 min read

Originally published on naturalrefrigerants.com in June 2026.



ATMO America: Flow Environmental Systems CO2 Heat Pumps Help Major American Tech Company Decarbonize


The water-to-water units replace legacy gas boilers, upgrading heat recovered from data center cooling to deliver 180°F hydronic and domestic hot water.

A major American tech company is decarbonizing hydronic space heating and domestic hot water production in its San Francisco Bay Area buildings by replacing legacy gas boilers with water-to-water CO2 (R744) heat pumps manufactured by Flow Environmental Systems.


In these retrofit applications with an existing variable air volume (VAV) distribution system, the six-pipe unit delivers 180°F (82°C) hydronic water and 140°F (60°C) domestic hot water from data center cooling waste heat, according to Tom Brown, Senior Project Manager at Accel Air Systems. Brannon Wynn, Project Executive at MAI Construction, joined Brown in a presentation at ATMOsphere America Summit 2026 to outline the design and installation of the units.


The event, organized by ATMOsphere, publisher of NaturalRefrigerants.com, took place June 2‒3 in Tarrytown, New York.


Brannon Wynn, Project Executive at MAI Construction, presenting at ATMO America 2026.
Brannon Wynn, Project Executive at MAI Construction, presenting at ATMO America 2026.

“As part of this electrification project, our long-term client was not seeking to go with natural refrigerants,” Wynn said. “However, as we began investigating options, we started to identify that a natural refrigerant solution, specifically Flow’s [CO2] heat pump, would meet their needs better than anything else.”


The project: The company’s design requirements for decarbonizing four occupied office buildings, ranging from 120,000ft² (11,150m²) to 180,000ft² (16,720m²), included reducing heating-related natural-gas consumption by 90% without disrupting operations.

  • Each building houses a first-floor data center with a cooling load of roughly 1,000TR (3.5MW), providing a continuous heat source.

  • Using CO2 allowed the solution to fit within the rooftop footprint of the existing boiler and domestic hot water heater, according to Brown.

  • “By the time we started stacking up the reduced electrical cost from serving only one piece of equipment, the reduced roofing and the avoidance of changing out the VAV to deal with lower temperature water, the cost delta for the CO2 solution was only 3% more than a conventional synthetic refrigerant system,” Wynn explained. He added that the combined COP of 3‒6 delivers a payback period of less than 1.5 years.


Preparation/installation: The project team and the end user’s technicians traveled to Flow’s Minnesota facility for equipment training and factory acceptance testing.


  • “We spent three days putting our hands on the units, asking questions and understanding how it worked, which helped the maintenance team buy into the product,” Wynn said, noting that legacy synthetic heat pump systems at the end user’s site had experienced a high failure rate.

  • To reduce installation time, Accel Air Systems prefabricated skid-mounted modular units that included the CO2 heat pump and a gas boiler capable of meeting the building’s full heating load as a backup.

  • Over a weekend, the team installed the skids and restored heating using the boiler to bring the building back up to temperature before commissioning the heat pumps the following week.


Lessons learned: At the time of the ATMO event, two of the four systems were installed and operating, with the third scheduled for installation the following weekend.


  • “Although we designed the CO2 heat pump system to cover 93% of the building’s heating load, in reality, it’s covering 100%,” Brown said, noting that the first installation took place in February.

  • One challenge the design team faced was educating the end user’s maintenance personnel about the benefits of allowing the CO2 system to idle at a 150°F (66°C) return water temperature, which maintains loop stability.

  • “Once the building warms up, it recycles the return water and satisfies the heating demand,” Brown said. “If we don’t need 180°F, we can achieve a better COP at lower temperatures. We control the system using a return-water setpoint instead of a supply-water setpoint.”


Quotable: “For our work in seeking out an alternative solution, we were the only vendor awarded the company’s sustainable procurement award out of a pool of 10,000 companies,” Wynn said. “It is their top sustainability award across the organization, and we are very proud of it.”


If you're looking for a commercial construction partner with decades of local experience and expertise in sustainable construction, reach out today.

Comments

bottom of page