Quantity the change in which is equal to the sum of heat, , brought to the system and work, , performed on it, . Also called thermodynamic energy.
Sources: Green Book, 2nd ed., p. 48 [Terms] [Book] PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 976 [Terms] [Paper]