and the United Kingdom), its use has declined or has been replaced in other parts of the world. For instances, propane has about 15,000 BTUs per pound and wood (dry) has abut 7,000 BTUs per pound.Īlthough it is still used 'unofficially' in some metric English-speaking countries (such as Canada, the U.S. This is the standard measurement used to state the amount of energy that a fuel has as well as the amount of output of any heat generating device, including chickens in a poultry house.Īll combustible materials have a BTU rating. Knowing any two of the psychrometric values defines the other five values.Ī British Thermal Unit (BTU) is the amount of heat energy needed to raise the temperature of one pound of water by 1☏. A psychrometric chart is a convenient way to graphically describe the interrelationships between the seven physical and thermal properties. The above seven properties are used to describe ventilation principles. The interrelationship between air and the moisture it holds provides the basis for maintaining a suitable environment. The seven physical and thermal properties are: Dry-bulb temperature An understanding of these characteristics and their relations to each other will help to better understand ventilating principles. Seven physical and thermal characteristics are used to describe air and water vapor mixtures. The air’s capacity to absorb heat and moisture depends on its characteristics. Psychrometrics is the study of the physical and thermal properties of air and water vapor mixtures.