Hyatt Regency Maui Resort and Spa

Heat Recovery for Domestic Water and Pool Heating, Design

Heat Recovery for Domestic Water and Pool Heating, Design - Maui, HI


The Hyatt Regency Maui is a 632,000-square-foot, 815-room hotel. This $1.4 million project involved the renovation of mechanical and plumbing systems serving the resort, including heating the swimming pool (approximately 1 million gallons and a half acre of surface area). Because the island of Maui is subject to some of the nation's highest costs for electricity, fuel oil, and propane, many cost-effective, energy reducing features were incorporated.


Source Award
Maui Electric Energy Efficiency Award
2001 Excellence in Engineering Award, ASHRAE Illinois Chapter
2002 Technology Award, ASHRAE Region VI (first place)
2003 Society-Level Technology Award, ASHRAE (first place)


Energy that would otherwise have been rejected to the atmosphere through the building's cooling towers was recovered from both the chilled water and condenser water systems and reused for the purposes described below.

The domestic hot water heating system uses a 96.7-ton heat pump to recover heat from the building's chilled water return mains, and then transfers that energy to the domestic hot water system. This process also cools the chilled water return, so less energy is consumed by the chillers and cooling towers.

  • The chilled water source heat pump provides domestic hot water at 40% savings over fossil fuel.
  • Five hot water storage tanks with a total capacity of 7,345 gallons were installed to allow recovered energy to be stored for use during periods of high hot water demand.
  • As a back-up for peak demands and to boost temperature for the laundry and kitchen loads, two semi-instantaneous, steam-fired domestic hot water heaters were also installed.

Lowered demand on the steam boilers for domestic hot water led to a significant decline in fuel oil consumption after this system became operational.

The swimming pool heat recovery system uses a plate-and-frame heat exchanger to recover heat from kitchen refrigeration units and the central plant chillers to heat the resort's swimming pools.

  • This design utilizes pool water for water-cooled refrigeration units to replace the previously used and less efficient air-cooled kitchen refrigeration condensing units.
  • The heat exchanger was specified with titanium plates for corrosion protection against the swimming pool water.
  • Cooling tower energy, make-up water, and treatment chemical consumption were reduced.

Renovation also included new, energy efficient chillers and upgraded mechanical room ventilation to comply with ASHRAE Standard 15.

  • Plant operation was automated through the existing EMS.
  • The central plant was reconfigured from 500/360/360 tons to 500/500/150 tons based on load analysis.
  • Major equipment was prepurchased based on life cycle cost analysis.