Mission Inn Hotel & Spa

Our HVAC and electrical solutions helped a historic hotel achieve significant energy savings and manage the electrical demands of large events.

Sunset view of the historic Mission Inn Hotel & Spa

Value Delivered

To help The Mission Inn Hotel & Spa meet its demanding commercial HVAC energy-saving objectives, EMCOR Services Mesa Energy provided design-build chiller plant replacement and electrical upgrades on a fast-track schedule.

By working closely with the owner, architect, subcontractors, local authorities, and utilities, we helped satisfy the city's stringent historic design criteria, and shorten the historic review process from six to less than two weeks.

We had their new central plant pre-built and shipped in two sections, and assembled it on site. This modular approach helped maintain the hotel's historic character, minimize the central chiller plant's footprint, and allow for future needs.

Our upgrade of their building automation protocol enabled integration of the new equipment, and helped reduce installation costs for labor, conduit, and wire.

To prepare the client to pursue ENERGY STAR certification, the new plant’s variable speed drive technology uses less power, dramatically reducing energy consumption at lower loads. Also, the counterflow cooling towers use up to 45 percent less water, and our side-stream separator helps improve condenser water condition. Their new system also uses R-134A refrigerant, which meets the U.S. Green Building Council's LEED certification standard.

Finally, to resolve that The Mission Inn Hotel & Spa was underpowered and had overloaded its circuitry during their Festival of Lights tourist attraction, we were able to provide electrical renovation through our affiliated EMCOR company, Dynalectric L.A. Our electrical solutions’ built-in redundancy further protects against downtime during key events, while simplifying electrical maintenance.

Because we planned and scheduled carefully to minimize the impact on guests and surrounding businesses, they made a smooth transition in time for peak cooling season.

Client Objectives 

The client wanted to support critical current and future business needs by increasing HVAC capacity and efficiency, and upgrading electrical service, to help them obtain ENERGY STAR certification.


Our HVAC retrofit solution involved replacing the hotel's 350-ton industrial chiller plant with a more efficient 600-ton modular unit and performing a major electrical upgrade.

The new plant includes:

  • Two centrifugal water-cooled chillers with factory-mounted variable-flow drives
  • Two 2-cell stainless steel cooling towers with induced-draft, counterflow design, capable of cooling 2,000 gallons of water per minute
  • Chilled and condenser water pumps with variable speed drives
  • Cooling tower filtration and chemical feed system
  • Chilled water system expansion tank and air separator
  • Two electric fan coil units for central plant air conditioning
  • Ventilation fan with gravity back-draft damper
  • Central plant industrial refrigerant monitoring system
  • Magnetic flow meter for monitoring the flow of main chilled water distribution
  • Six automated isolation control valves

In addition to trenching new chilled water lines to an existing tunnel, and performing all piping services to connect the chiller plant, cooling tower system, and other equipment, we installed:

  • New chilled water piping to and within the plant
  • Supply and return piping for the cooling towers
  • Fan coil units
  • Water treatment devices
  • Water source heat exchanger as part of the condenser loop

To set the towers, the company also installed:

  • Grade beams
  • Structural pads
  • Structural steel

We then craned the modular central chiller plant into place. Additionally, we upgraded the plant's existing direct digital control system to the building automation and control neworks (BACNet) protocol, enabling it to better handle the new commercial cooling equipment. Rather than pulling wire from all components back to the main controller, the company simply pulled the wire to the closest controller, from which BACnet can relay information throughout the system.

In collaboration with Dynalectric L.A. we resolved electrical performance issues, by working with the local utilities to bring 3,000 amperes of 460-volt power to the central plant. Half of these amperes serve the central plant, and the parking garage lighting and exhaust system, while the other half has been reserved for future requirements. 

Client Background

The Mission Inn Hotel & Spa is a historic landmark hotel in downtown Riverside, California that is considered the largest Mission Revival style building in the United States.