For the multimeter and nameplate methods, total power is first computed and then multiplied by the annual operating hours (and by the quantity multiplier for the nameplate method) to obtain annual energy use.

\begin{equation}\label{eq:electricity-reduction-energy-use} E = P \cdot n \cdot t_{op}\end{equation}

Symbols

\(E\)	Annual energy use \([\unit{ \kilo\watt\hour\per\year}]\)
\(P\)	Power draw per load \([\unit{ \kilo\watt}]\)
\(n\)	Quantity multiplier (number of identical loads) \([\unit{ \unitless}]\)
\(t_{op}\)	Annual operating hours \([\unit{ \hour\per\year}]\)