The converged heat loss per unit length is scaled by pipe length and annual operating time. Dividing by system efficiency converts heat loss at the pipe surface to the equivalent heat input required from the heating system.

\begin{equation}\label{eq:insulated-pipe-annual} Q_{annual} = \frac{q_L \cdot L \cdot t_{op}}{\eta}\end{equation}

Symbols

\(Q_{annual}\)	Annual heat loss \([\unit{ \watt\hour\per\year}]\)
\(q_L\)	Converged heat loss per unit length \([\unit{ \watt\per\meter}]\)
\(L\)	Total pipe length \([\unit{ \meter}]\)
\(t_{op}\)	Annual operating hours \([\unit{ \hour\per\year}]\)
\(\eta\)	Heating system efficiency (0–1) \([\unit{ \unitless}]\)