The Energy Metabolism Laboratory or Calorimetry Laboratory, adjacent to the Metabolic Research Unit, operates four room (indirect) respiration calorimeters designed for both children and adults. Each room is designed to measure energy expended over periods of several minutes up to 24 hours. Energy is calculated from the amounts of oxygen consumed and carbon dioxide produced while an individual is in the room. A smaller calorimeter is used for infants and children up to 2 years of age. A portable calorimeter has been placed at Texas Children's Hospital to measure the energy expenditure of prematurely born infants. The Energy Metabolism Laboratory also operates an exercise laboratory.