ASHRAE Terminology

A Comprehensive Glossary of Terms for the Built Environment

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(1) integral covering, sometimes fabric reinforced, that is applied over insulation. Also, the core, shield, or armor of a cable to provide mechanical or environmental protection. (2) sealed space around a piece of equipment or a storage unit, through which a thermal medium can be circulated.


concentrated airstream formed as primary air leaves the diffuser.

jet cooling

quick chilling process using air at very high speed forced around the products, usually while those products are continuously moving on a conveyor belt. Compare to air-blast cooling.

jet freezing

quick freezing process using cold air at very high speed forced onto the produce. Also called blast freezing.

jet pump

ejector or injector pump.

jind filter

a filter used to collect the ASHRAE dust passing a device during an arrestance test.

Josephson effect

set of quantum mechanical phenomena occurring when a current flows through an (electrically) weak link or junction connecting two superconductors (e.g., by tunneling through a dielectric barrier or by flowing through a sufficiently narrow constriction in a superconducting material).

Joule-Thomson effect

ratio of temperature change to pressure change (dT/dp) of an actual gas in a process of throttling or expansion without doing work or interchanging heat.