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Economizer Educational Demo


In an effort to save taxpayer money and natural resources, the Capitol Complex uses cool outside air to directly cool the interior of buildings whenever possible. This is called “economizer” cooling. When the outside air temperature and humidity are low enough, the air handling units open the outside air dampers, mixing cool, outside air with the return air from the building to provide cool air to the building’s interior rooms. Even when it’s cold outside, office buildings sometimes require cooling to maintain a comfortable temperature because heat is generated by people, computers, lights and other equipment.

Demonstration Steps

Step One

  • Cool, outside air is pulled into the unit.
  • Air is returned from the building at a slightly higher temperature than it was supplied.
  • The cool, outside air mixes with the warmer return air to provide cool air to rooms throughout a building.

Step Two

  • Outside air dampers are opened when the outside air temperature and humidity is low enough.

Step Three

  • The warmer return air is mixed with the cool, outside air which brings the air to a comfortable temperature.

Step Four

  • Cooling coils are a series of pipes that have cold water running through them. When air flows over the cold pipes, it cools the air. The cold water that is supplied to the cooling coils is from a chiller, which uses a lot of energy when running.
  • By bringing the supply air to a comfortable temperature with naturally cooled air, energy is saved because the chiller does not need to provide cold water to the cooling coils as much.