A human calorimeter for the direct and indirect measurement of 24 h energy expenditure.
1. A calorimeter for the continuous measurement of heat production and heat loss in the human subject, for at least 24 h, is described. The calorimeter operated on the heat-sink principle for direct calorimetry and an open-circuit system for indirect calorimetry. 2. Sensible heat loss was measured using a water-cooled heat exchanger, and the temperature of water entering the heat exchanger was controlled to maintain a mean temperature gradient of zero across the chamber walls. 3. Evaporative heat loss was determined from ingoing and outgoing wet-and-dry bulb temperatures and air flow-rates. 4. Problems associated with the calculation of evapoative heat loss and the estimation of the volume of incoming air in open-circuit systems are considered. 5. The calibration, limits of accuracy, sources of error and experiments with subjects are discussed.
D000328:Adult; D001833:Body Temperature Regulation; D002151:Calorimetry / Q000295:instrumentation / Q000379:methods*; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged