The heat loss is the sensible heat required to raise the temperature of the fixture material from its initial temperature to the final (furnace) temperature, adjusted by a correction factor. This represents energy absorbed by the fixtures that is not available for the primary heating process.

\begin{equation}\label{eq:fixture-heat-loss} Q = \dot{m} \cdot c_p \cdot (T_\text{final} - T_\text{initial}) \cdot f_\text{corr}\end{equation}

Symbols

\(Q\)	Heat loss \([\unit{ \btu\per\hour}]\)
\(\dot{m}\)	Feed rate of fixture material \([\unit{ \pound\per\hour}]\)
\(c_p\)	Specific heat of fixture material \([\unit{ \btu\per\pound\degreeFahrenheit}]\)
\(T_\text{final}\)	Final temperature of fixture \([\unit{ \degreeFahrenheit}]\)
\(T_\text{initial}\)	Initial temperature of fixture \([\unit{ \degreeFahrenheit}]\)
\(f_\text{corr}\)	Correction factor \([\unit{ \unitless}]\)