# 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
In scenario 2\({}^{\prime}\) for natural gas combustion, the annual CED is 2075 GJ-y\({}^{-1}\) and 1659.8 MJ-m\({}^{-2}\).y\({}^{-1}\) of the GH area, meaning CED is reduced by 24.9% compared to scenario 1\({}^{\prime}\). The biomass combustion scenarios (scenarios 3\({}^{\prime}\) and 4\({}^{\prime}\)) have the lowest CED at 481.3 GJ-y\({}^{-1}\) expressed as target value per unit GH of area 385.1 MJ-m\({}^{-2}\).y\({}^{-1}\). This means a reduction in CED by 82.6% compared to the coal combustion scenario (Table 8). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Analysis Stage**} & \multicolumn{6}{c}{**Scenario/Fuel**} \\ \hline  & \multicolumn{2}{c}{**1**} & \multicolumn{2}{c}{**2**} & \multicolumn{2}{c}{**3**} & \multicolumn{2}{c}{**4**} \\  & \multicolumn{2}{c}{**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 & 384,521 & 100.0 & 186,375 & 100.0 & 389,576 & 100.0 & 347,836 & 100.0 \\ fuel + electricity & 408,058 & 106.1 & 199,287 & 106.9 & 406,782 & 104.4 & 365,042 & 104.9 \\ CF (CO\({}_{2}\)-eq) & 458,305 & 119.2 & 212,604 & 114.1 & 25,600 & 6.6 & 23,013 & 6.6 \\ \hline \end{tabular}
\end{table} 
Table 7: Annual emissions of carbon dioxide and CF—comparison of the analysis stages. CF in the coal burning scenario (scenario 1\({}^{\prime}\)) is 226,054 kg CO\({}_{2}\)-eq.y\({}^{-1}\), and per unit cultivation area is 180.8 kg CO\({}_{2}\)-eq.m\({}^{-2}\)-y\({}^{-1}\). Scenario 2\({}^{\prime}\) has an absolute value of 105,089 kg CO\({}_{2}\)-eq.y\({}^{-1}\), target value per unit area is 84.1 kg CO\({}_{2}\)-eq.m\({}^{-2}\)-y\({}^{-1}\). Combustion of natural gas results in a 53.5% reduction compared to scenario 1\({}^{\prime}\). In scenario 3\({}^{\prime}\), the CF in absolute terms is 14,326 kg CO\({}_{2}\)-eq.y\({}^{-1}\) and the specific value per unit area is 11.5 kg CO\({}_{2}\)-eq.m\({}^{-2}\)-y\({}^{-1}\), i.e., only 6.4% CF was determined for the coal burning scenario. In scenario 4\({}^{\prime}\) involving the combustion of wood chips, the CF is 13,063 kg CO\({}_{2}\)-eq.y\({}^{-1}\), which converts to the specific value of 10.5 kg CO\({}_{2}\)-eq.m\({}^{-2}\)-y\({}^{-1}\), which is also 5.8% CF of scenario 1\({}^{\prime}\). The impact of energy carriers on the environment for a shorter period of GH operation (Table 9) is presented as the amount of carbon dioxide emissions expressed in kg CO\({}_{2}\)-eq.y\({}^{-1}\). The analysis shows that the increase in emissions due to the inclusion of electric drives in the GH technical systems and its heat source ranges from 5.4 to 8.5% of the emissions that can be attributed to fuel combustion. When comparing the results of scenarios 1-4 with the results of scenarios 1'-4\({}^{\prime}\), an increase in emissions related to electricity should be noted. This increase is due to a change in the GH operating regime: presumably, there are more favourable environmental conditions when the heating medium requirements are lower, which translates into lower fuel consumption, while maintaining the circulation of the heating medium in the system remains relatively constant. In the fossil fuel scenarios, the negative environmental impact is halved. In scenarios involving renewable fuels, we can see a reduction in environmental impact by reducing the CF. In absolute terms, this is a reduction of 175,698 kg of CO\({}_{2}\)-y\({}^{-1}\) when burning wood pellets (scenario 3\({}^{\prime}\)), which means a 92.5% negative environmental impact. In scenario 4\({}^{\prime}\) involving wood chip combustion, the annual emission reduction in absolute terms is 156,601 kg CO\({}_{2}\)-y\({}^{-1}\), which means 92.3% lower emissions.