For steam utility, the cost is based on annual steam use. For natural gas or other utility types, the cost is based on annual energy use.

\begin{equation}\label{eq:steam-reduction-cost-steam} C_{energy} = \dot{m}_{steam} \cdot r_{utility} \quad \text{(steam utility)}\end{equation}

\begin{equation}\label{eq:steam-reduction-cost-energy} C_{energy} = E_{use} \cdot r_{utility} \quad \text{(natural gas or other utility)}\end{equation}

Symbols

\(C_{energy}\)	Annual energy cost \([\unit{ \dollar\per\year}]\)
\(\dot{m}_{steam}\)	Annual steam use \([\unit{ \kg\per\hour}]\)
\(E_{use}\)	Annual energy use \([\unit{ \kJ\per\year}]\)
\(r_{utility}\)	Utility cost rate (steam utility) \([\unit{ \dollar\per\kg}]\)
\(r_{utility}\)	Utility cost rate (natural gas or other utility) \([\unit{ \dollar\per\kJ}]\)