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District Energy System

District Energy A Beneficial Alternative To Stand Alone Systems

06/09/2014

The Music City Center and Hyatt Place Nashville Downtown are the two newest customers of the Metro Nashville District Energy System.

For most facilities, district energy offers a more space efficient alternative to stand alone heating and cooling systems since steam and chilled water are delivered to the buildings from a central plant eliminating the need for chillers and boilers at each building.

Buildings are connected to the system via four pipes – a chilled water supply and chilled water return line, and a high-pressure steam supply and condensate return lines.

Buildings on the DES system use chilled water for space cooling/air conditioning and steam for space heating and domestic water heating.

Hyatt Place Nashville Downtown with DES connection
Hyatt Place Nashville Downtown with DES connection

Music City Center with DES Connections
Music City Center with DES connection

Most buildings pump the DES chilled water supply directly through their building cooling system and then return it to the DES. However, six customers have “decoupled” systems meaning the chilled water from the DES does not circulate directly through their building air handling units. Instead, it passes through one side of a plate and frame heat exchanger while the building circulates its own cooling system water through the other side of the heat exchanger.

Chilled water is delivered to customer facilities at approximately 40-42 degrees Fahrenheit, used for cooling purposes and returned back into the DES system at approximately 55 degrees Fahrenheit.

Detailed information about how chilled water is used for cooling

The majority of DES steam customers utilize hot water for space heating. A few customers use steam directly at the heating coils. Many also use steam to provide domestic water heating and some use steam as a heating source for kitchen and laundry purposes. High pressure steam is delivered to each customer location through the DES system, used for heating purposes and returned into the system as condensate.

Information about how steam is used in these buildings

Here are some additional photos showing how customers interface with DES.

Hyatt Place Nashville chilled water heat exchanger
Hyatt Place Nashville Downtown chilled water heat exchanger for space cooling

Music City Center chilled water heat exchanger
Music City Center chilled water heat exchanger for space cooling

Music City Center steam temperature controls
Music City Center steam temperature controls

Music City Center pipes feeding steam to heat exchangers
Music City Center pipes feeding steam to heat exchangers

Music City Center close up of heat exchanger
Music City Center close up of heat exchanger where steam heats water for space heating

Music City Center building hot water pumps
Music City Center building hot water pumps that send hot water to coils in air handlers where air is warmed

Hyatt Place Nashville Downtown space heating hot water pumps
Hyatt Place Nashville Downtown space heating hot water pumps

Hyatt Place Nashville Downtown chilled water pumps
Hyatt Place Nashville Downtown chilled water pumps with heat exchanger for cooling water in the building's cooling system

Hyatt Place Nashville Downtown DES metering system
Hyatt Place Nashville Downtown DES meeting system provides interface to customer's building management system