{\displaystyle JAZ={\frac {\int _{0}^{\text{Jahr}}{\dot {Q}}_{\text{Heiz}}\,\mathrm {d} t}{\int _{0}^{\text{Jahr}}P_{\mathrm {el} }\,\mathrm {d} t}}={\frac {Q_{\text{Heiz}}}{W_{\mathrm {el} }}}}