The electrical energy is calculated by multiplying the recovered heat, chiller COP, and chiller efficiency, then dividing by the compressor COP. This represents the electrical energy that would have been required to achieve the same cooling effect using a compressor-based system.

\begin{equation}\label{eq:water-heating-exhaust-electrical-energy} E_{elec} = \frac{Q_{rec} \cdot COP_{chiller} \cdot \eta_{chiller}}{COP_{comp}}\end{equation}

Symbols

\(E_{elec}\)	Electrical energy \([\unit{ \btu\per\hour}]\)
\(Q_{rec}\)	Recovered heat \([\unit{ \btu\per\hour}]\)
\(COP_{chiller}\)	Coefficient of performance for chiller \([\unit{ \unitless}]\)
\(\eta_{chiller}\)	Chiller efficiency \([\unit{ \unitless}]\)
\(COP_{comp}\)	Coefficient of performance for compressor \([\unit{ \unitless}]\)