# Cumulative Energy Demand and Carbon Footprint of the Greenhouse Cultivation System
## 3 Results and Discussion
### Cumulative Energy Demand and Carbon Footprint during the Use Phase
A comparison of the CED values for year-round operation and for the period shortened by the three coldest months reveals a 50.6% reduction in demand for coal combustion and 50.8% for natural gas combustion. The use of renewable fuels means a CED reduction of 48.5% when burning wood pellets and wood chips. In the case of a GH operated in Germany [1] assessed in terms of fuel consumption and electricity consumption over a similar lifetime, the CED values are lower. The difference may result from the locations of the analysed facilities and their slight distinctions in shape. The German multi-span greenhouse is more compact than the free-standing, even-span greenhouse studied in the present paper. Due to the abovementioned reasons, the results are not directly comparable. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Scenario/Fuel**} & \multicolumn{6}{c}{**CED**} & \multicolumn{6}{c}{**CF**} \\ \cline{2-9}  & **MJ y\({}^{-1}\)** & **MJ m\({}^{-2}\) y\({}^{-1}\)** & **MJ unit\({}^{-1}\) y\({}^{-1}\)** & **\%** & **kg** & **kg CO\({}_{2}\)-** & **kg CO\({}_{2}\)-** & **kg CO\({}_{2}\)-** & **\%** \\  & & & & **CO\({}_{2}\)-eqy\({}^{-1}\)** & **eq m\({}^{-2}\) y\({}^{-1}\)** & **eq m\({}^{-1}\) y\({}^{-1}\)** & **eq m\({}^{-1}\) y\({}^{-1}\)** & **\%** \\ \hline 1\({}^{\prime}\)/coal & 2,762,322 & 2209.9 & 9.2 & 100.0 & 226,054 & 180.8 & 0.754 & 100.0 \\ 2\({}^{\prime}\)/natural gas & 2,074,723 & 1659.8 & 6.9 & 75.1 & 105,089 & 84.1 & 0.350 & 46.5 \\ 3\({}^{\prime}\)/ wood pellets & 481,327 & 385.1 & 1.6 & 17.4 & 14,326 & 11.5 & 0.048 & 6.4 \\ 4\({}^{\prime}\)/wood chips & 481,327 & 385.1 & 1.6 & 17.4 & 13,063 & 10.5 & 0.044 & 5.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: CED and CF for individual scenarios expressed as absolute values, as well as specific values per unit area and per unit of a potted flower; GH operation of 273 days, from February till October. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Analysis Stage**} & \multicolumn{6}{c}{**Scenario/Fuel**} \\ \hline  & \multicolumn{2}{c}{**1\({}^{\prime}\)**} & \multicolumn{2}{c}{**2\({}^{\prime}\)**} & \multicolumn{2}{c}{**3\({}^{\prime}\)**} & \multicolumn{2}{c}{**4\({}^{\prime}\)**} \\  & **Coal** & \multicolumn{2}{c}{**Natural Gas**} & \multicolumn{2}{c}{**Wood Pellets**} & \multicolumn{2}{c}{**Wood Chips**} \\ \hline  & **kg CO\({}_{2}\) y\({}^{-1}\)** & **\%** & **kg CO\({}_{2}\) y\({}^{-1}\)** & **\%** & **kg CO\({}_{2}\) y\({}^{-1}\)** & **\%** & **kg CO\({}_{2}\) y\({}^{-1}\)** & **\%** \\ \hline fuel & 187,558 & 100.0 & 90,909 & 100.0 & 190,024 & 100.0 & 169,664 & 100.0 \\ fuel + electricity & 201,541 & 107.5 & 98,592 & 108.5 & 200,253 & 105.4 & 179,893 & 106.0 \\ CF (CO\({}_{2}\)-eq) & 226,054 & 120.5 & 105,089 & 115.6 & 14,326 & 7.5 & 13,063 & 7.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Annual emissions of carbon dioxide and CF—comparison of the analysis stages; GH operation of 273 days, from February till October. The CF values for scenarios 1\({}^{\prime}\)-4\({}^{\prime}\) were reduced by 50.7% for coal combustion and 50.6% for natural gas. Combustion of biomass in shorter periods of GH operation should reduce the emission of pollutants by 44.0% when using wood pellets, and by 43.2% when burning wood chips.