Total chilled water production represents the total amount of cooling required each hour by the campus buildings. Chilled water production is measured in tons of cooling. One ton of cooling is equivalent to 12,000 BTU per hour. For perspective, a typical home air conditioner is rate at 2 to 3 tons of cooling.
Iowa State utilizes five large chillers to provide chilled water for cooling the campus buildings. Four of the chillers are located in the campus power plant. The fifth chiller is located in the north chilled water plant.
The chillers produce chilled water at 40-42 deg F. This chilled water is pumped through the building equipment to cool the building. The chilled water picks up heat from the buildings and returns to the chillers at up to 55 deg F. The chillers cool the water again and return it to the buildings. At peak times, over 25,000 gallons of water are pumped through the buildings every minute.
The chilled water is used to provide comfort cooling for the building occupants but is also used for cooling research equipment, computer equipment, animal rooms, etc. Iowa State must provide chilled water to the campus 365 days per year.