# 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
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Scenario/Fuel**} & \multicolumn{5}{c}{**Energy**} \\ \cline{2-9}  & \multicolumn{3}{c}{**Useful**} & \multicolumn{3}{c}{**Final**} & \multicolumn{3}{c}{**Primary**} \\ \cline{2-9}  & **MWhr\(\cdot\)y\({}^{-1}\)** & **kWhr\(\cdot\)m\({}^{-2}\)y\({}^{-1}\)** & **\%** & **MWhr\(\cdot\)y\({}^{-1}\)** & **kWhr\(\cdot\)m\({}^{-2}\)y\({}^{-1}\)** & **\%** & **MWhr\(\cdot\)y\({}^{-1}\)** & **kWhr\(\cdot\)m\({}^{-2}\)y\({}^{-1}\)** & **\%** \\ \hline
1/coal & & & 1125.04 & 900.0 & 100 & 1553.31 & 1242.6 & 100 \\
2/natural gas & 679.77 & 543.82 & 100 & 933.89 & 747.2 & 83.0 & 1170.57 & 936.5 & 75.4 \\ \hline
3/wood pellets & & & & 966.21 & 773.0 & 85.9 & 259.59 & 207.7 & 16.7 \\
4/wood chips & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Energy performance of the GH. The CF per single potted flower in the reference scenario is 1245 kg CO\({}_{2}\)-eq-unit\({}^{-1}\).y\({}^{-1}\), and in the case of natural gas combustion 0.578 kg CO\({}_{2}\)-eq-unit\({}^{-1}\).y\({}^{-1}\), i.e., 46.4% less than in scenario 1. In scenarios with renewable fuels, the CF is 0.070 kg of CO\({}_{2}\)-eq-unit\({}^{-1}\).y\({}^{-1}\) of the potted flower when burning wood pellets, which is 5.6% CF when burning carbon and 0.063 kg CO\({}_{2}\)-eq-unit\({}^{-1}\).y\({}^{-1}\) when burning wood chips, which is 5.0% CF in scenario 1. In order to demonstrate the impact of energy carriers on the environment, the obtained results are broken down into individual stages of the analysis (Table 7), which provided information on carbon dioxide emissions expressed in kg CO\({}_{2}\):y\({}^{-1}\). In the first stage, emissions relating to fuel combustion are highlighted; the second one included emissions related to the generation of electricity used by drives in technical systems. The last item is cumulative CF, which is the final information on the environmental footprint of energy carriers in the use phase of GH. The analysis shows that the increase in emissions caused by the inclusion of electric drives in the technical systems of the analysed GH and its heat source ranges from 4.4 to 6.9% of the emission level that can be attributed to fuel combustion. The main impact regarding the use phase of GH is due to the fuel selection. In the fossil fuel scenarios, a reduction in the environmental footprint can be observed when natural gas is burned (scenario 2). When it comes to local emissions related to fuel combustion, an increase in carbon dioxide emissions, expressed in equivalent units, can be observed. In scenario 1, it is increased by 19.2% compared to the emission of coal combustion. In scenario 2 for natural gas combustion, there is an increase of 14.1% compared to local emissions. The adoption of renewable fuels in the form of biomass offers a significant reduction in environmental impact by reducing CF. In absolute terms, this is a reduction of 363,976 kg of CO\({}_{2}\):y\({}^{-1}\) when burning wood pellets (scenario 3), which means 93.4% of the negative impact on the environment. In scenario 4 involving the combustion of wood chips, the annual emission reduction in absolute terms is 324,823 kg CO\({}_{2}\):y\({}^{-1}\), which means 93.4% lower emissions as well. The results allow further analysis to determine the CED and CF values in the use phase for different operating periods. It was assumed to determine the CED and CF values in the event that the facility closes between November and February. Analytical work produced totals for annual CED for operation with 273 GH cultivation days. The operation of GH for growing flowers in pots with carbon combustion in the heat source (scenario 1\({}^{\prime}\)) consumes 2.762 GJ-y\({}^{-1}\) of energy, so the specific value referred to in the unit of the cultivated area is 2209.9 MJ-m\({}^{-2}\).y\({}^{-1}\).